url stringclasses 36
values | page_number int64 1 415 | extracted_answer_choices listlengths 1 17 | extracted_solution stringlengths 1 749 | improved_question_solution stringlengths 58 5.33k |
|---|---|---|---|---|
https://www.ttcho.com/_files/ugd/988b76_01ceeff230b24cbbb0125b2bfa3f3475.pdf | 1 | [
"\"A. e\"",
"\"B. H\"",
"\"C. 13 C\"",
"\"D. 12C\""
] | B is the correct answer. | Carbon-14 is the radioisotope of carbon with the longest half-life. It may be formed by the following reaction:
14N + 1n → 14C + X.
What is the identity of X?
(A). e
(B). H
(C). 13 C
(D). 12C |
http://chemistryrace.com/wp-content/uploads/2025/02/ChR_2025_answer_booklet.pdf | 19 | [
"\"free response\""
] | "57.37 h" | Caesium metal has been obtained historically by the electrolysis of caesium cyanide:
2 CsCN + 2e® → 2Cs + C2N2. Calculate how long (in hours) the electrolysis using 10 A current must run to produce enough cesium metal to form the eutectic alloy upon reaction with 250 g of potassium. Assume that the reaction proceeds ... |
http://chemistryrace.com/wp-content/uploads/2025/02/ChR_2025_answer_booklet.pdf | 7 | [
"NO CHOICES AVAILABLE"
] | 0.04103 mol dm³ | What is the molar concentration of air in an ordinary auditorium where Chemistry Race is held, in moldm³? Consider ideal behavior, a temperature of 20°C, a pressure of 100 000 Pa. |
http://chemistryrace.com/wp-content/uploads/2025/02/ChR_2025_answer_booklet.pdf | 16 | [
"NO CHOICES AVAILABLE"
] | 6.81 g ℓ−1 | It is known that the complexation reaction between Ca2+ and EDTA proceeds in a 1:1 mole ratio. Calculate the concentration of Ca2+ in g ℓ−1 if 42.50 ml of EDTA solution of concentration 0.10 mol dm−3 is used to titrate 25.00 ml of nejayote? |
http://chemistryrace.com/wp-content/uploads/2025/02/ChR_2025_answer_booklet.pdf | 42 | [
"\"free response\""
] | "free response answer" | Your task is to determine how many electrons the starting materials have to lose during the formation of one molecule of Mauveine A. (The answer is an integer). The oxidation reaction is represented by the equation: 2C6H7N + 2C7H9N → C26H23N4+ + 10e¯ + 9H+. Your task is to determine how many electrons the starting mate... |
https://www.mit.edu/~anugrah/files/MockIChOSolutions.pdf | 13 | [
"NO CHOICES AVAILABLE"
] | O=W=O with -0.5 for no lone pairs | Problem 3. Wolfram, 钨, вольфрамma التنغست. Draw the Lewis structure of tungstate (WO₄²⁻).
Draw the Lewis structure of tungstate (WO₄²⁻). |
http://chemistryrace.com/wp-content/uploads/2025/02/ChR_2025_answer_booklet.pdf | 20 | [
"NO CHOICES AVAILABLE"
] | 2 [Na(NH3)6]+e → 2NaNH2 + 10 NH3 + H2 | Electrides are compounds where an electron acts as an anion, called a solvated electron. An example of one is [Na(NH3)6] + e¯. This species can decompose via a redox reaction into three products. Write the full equation of the decomposition of [Na(NH3)6]+e¯. |
https://www.ttcho.com/_files/ugd/988b76_48944f6ace684143bfdc9080fca59862.pdf | 10 | [
"\"Acetic acid\"",
"\"Acetic anhydride\"",
"\"Acetyl bromide\""
] | "Acetic acid" ||| "Acetic anhydride" ||| "Acetyl bromide" | For Reaction 2, it is specified that it is an esterification reaction involving an acid chloride and an alcohol to yield an ester. In place of the acid chloride, the corresponding carboxylic acid or acid anhydride may be used. Possible alternatives noted include acetic acid or acetic anhydride.
For Reaction 2, sugges... |
https://facultystaff.richmond.edu/~lrunyenj/bio201/04bio201%20exam%201%20key.pdf | 1 | [
"NO CHOICES AVAILABLE"
] | 8 | Imagine an individual with the genotype AaDdggRr, where each of these genes is on a different chromosome. How many different gamete types can be formed by this individual with the genotype AaDdggRr? |
https://www.mit.edu/~anugrah/files/MockIChOSolutions.pdf | 17 | [
"\"free response\""
] | "μ(Ο-Η) = .94118 amu, μ(O-D) = 1.7778 amu" | You should use integer molar masses: m(H) = 1 amu, m(O) = 16 amu. Calculate, in amu, the reduced mass of the O-H bond and the O-D bond respectively. |
http://chemistryrace.com/wp-content/uploads/2023/02/chemistry_race_2023_answers-book.pdf | 8 | [
"NO CHOICES AVAILABLE"
] | chlorine (Cl2) | An entrepreneur is setting up an element shop which sells samples of all of the chemical elements with atomic numbers less than zinc to chemistry fans. As an opening promotion, they are selling all of the elements at £5 per gram. Excited to get my hands on some samples, I bought 1 liter balloons of all of the gases the... |
http://chemistryrace.com/wp-content/uploads/2024/02/ChR_2024_answer_booklet.pdf | 33 | [
"NO CHOICES AVAILABLE"
] | 2.1 g | Here's the text addition to ensure the question is answerable:
In such a titration, the phenol is brominated three times, and the end of the titration is indicated by the fact that the additional bromine no longer reacts, but remains in the titrated mixture. The molar amount of bromine can be calculated based on the ... |
https://www.cheminst.ca/wp-content/uploads/2022/12/Canadian-Chemistry-Olympiad-2022-EN_key.pdf | 16 | [
"\"free response\""
] | "Vmin = 2.75 L" | Initial moles of A and B are nA = 0.0204 mol and nB = 0.184 mol. The reaction is 2B → A. The formula for Vmin is given as Vmin = nA RT / P where nA is the number of moles of A at the completion of the reaction. Calculate the value of Vmin, the minimum volume of compartment 1 at 1 atm. The initial moles of A and B are n... |
http://chemistryrace.com/wp-content/uploads/2025/02/ChR_2025_answer_booklet.pdf | 8 | [
"\"cysteine\"",
"\"methionine\""
] | "cysteine" | Taurine (from Latin *taurus* – after the first isolation from ox bile) is a small non-proteinogenic amino acid. Its systematic name is 2-aminoethanesulfonic acid. Being a sulfonic acid, it has no carboxyl group, which is an integral part of all proteinogenic amino acids. Taurine is a common ingredient in energy drinks ... |
http://chemistryrace.com/wp-content/uploads/2023/02/chemistry_race_2023_answers-book.pdf | 8 | [
"NO CHOICES AVAILABLE"
] | 95 % | Pepík wanted to pickle some vegetables in vinegar at home to preserve them. Because he worked in a chemical laboratory and wanted to save money, he stole some acetic acid from the laboratory to make a pickling liquor. When he got home, he realised he had forgotten the concentration of the looted acid. As an experienced... |
https://www.ttcho.com/_files/ugd/988b76_01ceeff230b24cbbb0125b2bfa3f3475.pdf | 28 | [
"\"A. MgBr₂\"",
"\"B. Mg/Et₂O\"",
"\"C. Mg / HCl (aq)\"",
"\"D. Mg/Br₂ (g)\""
] | B is the correct answer | Formation of a Grignard reagent from an alkyl bromide. Requires magnesium in the presence of an ethereal solvent. What is the identity of reagent / reactant (iv)?
(A). MgBr₂
(B). Mg/Et₂O
(C). Mg / HCl (aq)
(D). Mg/Br₂ (g) |
http://chemistryrace.com/wp-content/uploads/2025/02/ChR_2025_answer_booklet.pdf | 20 | [
"NO CHOICES AVAILABLE"
] | 0.66 g/l | Classic Coca-Cola has a pH of 2.37, in comparison 8% vinegar has a pH of approximately 2.6. Coca-Cola is therefore more acidic than the vinegar commonly used for descaling. The pH of Coca-Cola is due solely to phosphoric acid, which is a tri-saturated acid with pKa1 = 2.14, pKa2 = 7.20, and pKa3 = 12.37. Calculate the ... |
https://www.ttcho.com/_files/ugd/988b76_ba0cb3177d05436da273a400a037ed01.pdf | 25 | [
"(i) CO2 (1 mark)",
"(ii) methylamine / CH3NH2 (2 marks)"
] | (i) CO2 ||| (ii) methylamine / CH3NH2 | Methyl isocyanate reacts with water to yield: (i) a colourless gas that turns limewater milky and (ii) a gas that has a strong odour similar to fish. Identify products (i) and (ii). (3 marks) |
https://facultystaff.richmond.edu/~lrunyenj/bio201/04bio201%20exam%201%20key.pdf | 4 | [
"\"A = straight",
"a = kink",
"B = short",
"b = long\""
] | "A = straight ||| a = kink ||| B = short ||| b = long" | Normal hedgehogs have straight fur and long whiskers. Mutant hedgehogs have been isolated with either kinked fur or short whiskers. The genes for each of these characters are on different chromosomes. The allele for kinked fur is recessive to the allele for straight fur. The allele for short whiskers is dominant to the... |
https://www.ttcho.com/_files/ugd/988b76_01ceeff230b24cbbb0125b2bfa3f3475.pdf | 2 | [
"\"A. 38.000\"",
"\"B. 37.965\"",
"\"C. 37.963\"",
"\"D. 39.948\""
] | D is the correct answer. | Argon consists of three stable isotopes:
Isotope Mass Abundance
Ar-36 35.968 0.334%
Ar-38 37.963 0.062%
Ar-40 39.963 99.604%
What is the atomic mass of Argon?
(A). 38.000
(B). 37.965
(C). 37.963
(D). 39.948 |
http://chemistryrace.com/wp-content/uploads/2024/02/ChR_2024_answer_booklet.pdf | 10 | [
"NO CHOICES AVAILABLE"
] | 1.996 megatons | A huge deposit of lithium ore is located under the Czech mountain Cínovec, which has an estimated mass of 134 million tons and an average lithium content of 0.28% (by weight). How many megatons of lithium carbonate could be produced from this reserve? |
http://chemistryrace.com/wp-content/uploads/2024/02/ChR_2024_answer_booklet.pdf | 8 | [
"NO CHOICES AVAILABLE"
] | (The structural formula of gallic acid as depicted in the text.) | An important group of tannins are the esters of gallic acid and saccharides. A typical example is tannic acid (see appendix). The heating of this acid causes hydrolysis of the ester bonds and the release of gallic acid, which is used to make oak gall ink. Draw the structural formula of gallic acid. Hint: all of the est... |
https://www.ttcho.com/_files/ugd/988b76_01ceeff230b24cbbb0125b2bfa3f3475.pdf | 33 | [
"\"A. 2\"",
"\"B. 3\"",
"\"C. 4\"",
"\"D. 6\""
] | "B. 3" | Nuclear Magnetic Resonance (NMR) Spectroscopy is a powerful tool for the structural elucidation of unknown compounds. In 'H NMR, protons which have identical chemical (and magnetic) properties will appear as a single peak in the NMR spectra. For example, the following is a low resolution spectra of dimethyl ether:
Ho... |
http://chemistryrace.com/wp-content/uploads/2022/02/cambridge_chemistry_race_2022_answers.pdf | 3 | [
"NO CHOICES AVAILABLE"
] | 0.1614 g/L | Helium is formed by radioactive decay of uranium in the crust and accumulates in pockets deep beneath the surface. This makes helium hard to find, and expensive to extract. Helium is unusual because, if it is not recaptured after use, it has sufficiently low density to escape the Earth's gravity. Work out the density o... |
https://www.ttcho.com/_files/ugd/988b76_01ceeff230b24cbbb0125b2bfa3f3475.pdf | 30 | [
"\"A: Nylon-6,6\"",
"\"B: PTFE\"",
"\"C: PVC\"",
"\"D: Cellulose\""
] | A is the correct answer | Consider the ring opening polymerization of caprolactam: Which of the following polymers would you expect to have similar physical properties to the polymer above?
(A). Nylon-6,6
(B). PTFE
(C). PVC
(D). Cellulose
|
https://www.mit.edu/~anugrah/files/MockIChOSolutions.pdf | 13 | [
"NO CHOICES AVAILABLE"
] | Formula = (WO₃)ₓₙO₂⁻ | Problem 3. Wolfram, 钨, вольфрамma التنغست. Draw the structure of a tungstate polymer, and write a generic formula in terms of Xₙ, the number of monomer units in the polymer (henceforth referred to as the polymer length).
[O-W-O-W-O]
|| ||
O O
n
Anything reasonable will be accepted.
Question: Dra... |
https://www.ttcho.com/_files/ugd/988b76_01ceeff230b24cbbb0125b2bfa3f3475.pdf | 23 | [
"A: UV light",
"B: Ninhydrin",
"C: Methyl orange",
"D: Phenolphthalein"
] | A is the correct answer | Given that the stationary phase is silica gel, a polar substance, which of the following is likely to be the reaction that was performed?
What is the best method for visualization of the TLC spots of this reaction mixture?
(A). UV light
(B). Ninhydrin
(C). Methyl orange
(D). Phenolphthalein |
https://www.ttcho.com/_files/ugd/988b76_01ceeff230b24cbbb0125b2bfa3f3475.pdf | 23 | [
"A: 0.29",
"B: 0.72",
"C: 0.00",
"D: 1.20"
] | A is the correct answer | The Rf value can be calculated using the formula: Rf = distance moved by spot / distance moved by solvent from the starting position of the spot. The distance moved by the spot of the starting material is reported as 0.95 cm, while the total distance moved by the solvent is 3.1 cm.
What is the Rf of the starting mate... |
https://www.ttcho.com/_files/ugd/988b76_01ceeff230b24cbbb0125b2bfa3f3475.pdf | 34 | [
"\"A: I only\"",
"\"B: II only\"",
"\"C: II and III only\"",
"\"D: III and IV only\""
] | "C is the correct answer" | The Thalidomide disaster occurred in the 1950s and resulted in 1000s of babies being born with severe birth defects. Isomer C was used for the treatment of morning sickness in pregnant women, while isomer D was responsible for the birth defects. However, even if a pregnant woman took exclusively isomer C, birth defects... |
https://www.mit.edu/~anugrah/files/2012CChOLocalSoln.pdf | 1 | [
"NO CHOICES AVAILABLE"
] | Thus the solid residue is CuO. | The compound [Cu(pydc)(amp)]·3H2O has formula C11H14CuN4O7 (pydc and amp are organic ligands containing aromatic rings). Thermogravimetric analysis shows that the compound thermally decomposes in two steps. The first weight loss peak accounts for a weight loss of approximately 15%. The second decomposition occurs betwe... |
https://www.ttcho.com/_files/ugd/988b76_ba0cb3177d05436da273a400a037ed01.pdf | 26 | [
"\"CO2\"",
"\"methylamine / CH3NH2\""
] | CO2, methylamine / CH3NH2 | Methyl isocyanate reacts with water to yield a colourless gas that turns limewater milky and a gas that has a strong odour similar to fish. Identify products (i) and (ii).
(i) a colourless gas that turns limewater milky and
(ii) a gas that has a strong odour similar to fish. Identify products (i) and (ii). |
https://uwaterloo.ca/chemistry/sites/default/files/uploads/documents/avogadro-exam-solution-2007.pdf | 7 | [
"\"A: CH\"",
"\"B: CH2\"",
"\"C: CH3\"",
"\"D: CH4\"",
"\"E: C3H4\""
] | "B: CH2" | A compound of carbon and hydrogen is found to be 85.6% carbon by mass and 14.38% hydrogen. What is the simplest formula of the compound?
<bold>A</bold> CH
*<bold>B</bold> CH2
<bold>C</bold> CH3
<bold>D</bold> CH4
<bold>E</bold> C3H4 |
http://chemistryrace.com/wp-content/uploads/2024/02/ChR_2024_answer_booklet.pdf | 62 | [
"NO CHOICES AVAILABLE"
] | rate of deposition = 0.91 nm yearly | The sample has g = 0.779 and in equilibrium g = 1.38. At t → ∞, K = 1/1.38 = 0.724. For the sample, tk_L = 0.816, therefore t = 8.8 × 10^6 years. Thus, the rate of deposition is calculated as 8×10^6 / 8.8×10^6. What is the rate of deposition if it is calculated as 8×10^6 / 8.8×10^6? |
http://chemistryrace.com/wp-content/uploads/2025/02/ChR_2025_answer_booklet.pdf | 7 | [
"NO CHOICES AVAILABLE"
] | 4 KClO3 → KCl + 3 KClO4 | One of the reactions occurring in the reaction mixture is disproportionation, the decomposition of potassium chlorate into other potassium salts A and B, in which the chlorine atom has oxidation states of -1 and +7, respectively. No additional products are formed during this reaction. Write the balanced equation for th... |
http://chemistryrace.com/wp-content/uploads/2024/02/ChR_2024_answer_booklet.pdf | 12 | [
"NO CHOICES AVAILABLE"
] | Pyruvic acid (pyruvate) | Glycols (derived from Greek, meaning 'sweet') are 1,2-diols. The simplest molecule of this class, ethylene glycol (ethane-1,2-diol), is toxic because it is metabolised in the body to oxalic acid (HOOCCOOH). However, propylene glycol (propane-1,2-diol) is not toxic, because it is metabolised into a molecule which is als... |
http://chemistryrace.com/wp-content/uploads/2025/02/ChR_2025_answer_booklet.pdf | 49 | [
"NO CHOICES AVAILABLE"
] | 6.02 °C | Pepa bought a cold beer at the store, but on the way home he realised that he had mistakenly bought non-alcoholic beer. So he decided to fix it by adding 20g of ethanol for UV-VIS spectroscopy (purity min. 99.99%), which he stores in a refrigerator at 4°C. But as an educated chemist, he knew that mixing water with etha... |
https://www.mit.edu/~anugrah/files/MockIChOSolutions.pdf | 11 | [
"\"free response\""
] | "0.340 V" | We use the simplified reaction Cu2+ + I° → Cu⁺ + 2 I2, has E° = -.39V, so K = 2.529*10-7, K/Ksp is a huge number! Thus, it is not hard to see that the reaction goes to completion. Thus, past the endpoint the dominant species are I₂ and I, with concentrations of 5 mM and 10 mM. These can be plugged directly into the Ner... |
https://www.mit.edu/~anugrah/files/MockIChOSolutions.pdf | 7 | [
"\"A = KNa₄Cu(HIO₆)₂·12H₂O or KNa4Cu(IO₄)2O3·13H₂O etc.\""
] | "free response answer" | Determine the formula of A, and write the overall reaction for the formation of the copper (III) periodate complex A according to the procedure. Ratio of Cu:I:O:H = 1:2:24:26. Leftover charge: 1(3)+2(7)+24(-2)+26(1) = -5. Excess mass: 131 g/mol. Possible counterions are K, Na → 4Na, 1K. |
http://chemistryrace.com/wp-content/uploads/2024/02/ChR_2024_answer_booklet.pdf | 10 | [
"NO CHOICES AVAILABLE"
] | 4 CH3COOK + AS2O3 → ((CH3)2AS)2O + 2 K2CO3 + 2 CO2
--- | The first discovered organometallic compounds are thought to be dicacodyl ((CH3)2AS)2 and dicacodyl oxide ((CH3)2AS)2O, which were obtained as brown oily liquids that smelled rather foul and fumed in the air. These substances were prepared by a rather unusual reaction of potassium acetate (ethanoate) with arsenic triox... |
https://www.ttcho.com/_files/ugd/988b76_48944f6ace684143bfdc9080fca59862.pdf | 17 | [
"\"Amide\"",
"\"Ester\"",
"\"Aromatic\""
] | "free response answer" | Identify three (3) functional groups in carbaryl. (3 marks)
Amide
Ester
Aromatic
(1 mark) x 3
Identify three functional groups in carbaryl. (3 marks) |
http://chemistryrace.com/wp-content/uploads/2023/02/chemistry_race_2023_answers-book.pdf | 24 | [
"NO CHOICES AVAILABLE"
] | £2.62 billion | I wish to fill the local pond with 3500m³ of water with a density of 1.08 g ml¯¹, which is to be made by mixing H₂O and D₂O. I buy deuterium oxide from a well-known chemical company for £1000l-1. Assume that H2O is free. Density of H2O, ρH₂O = 0.997 g ml-1. How much will it cost to fill the pond with 3500m³ of water wi... |
https://www.ttcho.com/_files/ugd/988b76_01ceeff230b24cbbb0125b2bfa3f3475.pdf | 2 | [
"\"A. e\"",
"\"B. 1H\"",
"\"C. 13C\"",
"\"D. 12C\""
] | B is the correct answer. | Carbon-14 is the radioisotope of carbon with the longest half-life. It may be formed by the following reaction: 14N + 1n → 14C + X. What is the identity of X in the reaction 14N + 1n → 14C + X?
(A). e
(B). 1H
(C). 13C
(D). 12C |
http://chemistryrace.com/wp-content/uploads/2025/02/ChR_2025_answer_booklet.pdf | 20 | [
"NO CHOICES AVAILABLE"
] | 57.37 h | Sodium and potassium, which are both solid at room temperature, if combined at the correct ratio famously form a highly reactive liquid alloy known as “NaK”. This is an example of a eutectic system, i.e. a homogeneous mixture possessing a melting point lower than the individual components. A lesser known alkali metal e... |
http://chemistryrace.com/wp-content/uploads/2024/02/ChR_2024_answer_booklet.pdf | 41 | [
"NO CHOICES AVAILABLE"
] | 18.12 µg | Like graphene, graphyne is a 2D allotrope of carbon which can form a covering on a surface. How much carbon (in µg) would be needed to completely cover this A5 page (148 × 210mm) with a single layer of graphyne? |
https://www.ttcho.com/_files/ugd/988b76_e3d21fc42bb24de4959d7250f0cfcb3a.pdf | 18 | [
"\"A. The purple colour disappears\"",
"\"B. No visible reaction\"",
"\"C. The orange colour disappears\"",
"\"D. A green solution is formed\""
] | A is the correct answer. | KMnO4/H⁺ is slowly added to compound A. KMnO4/H⁺ is an oxidizing agent, and compound A is capable of undergoing oxidation (primary alcohol to carboxylic acid). The oxidizing agent will undergo reduction, leading to the disappearance of the purple color. What will be observed when the KMnO4/H mixes with compound A?
(A... |
http://chemistryrace.com/wp-content/uploads/2023/02/chemistry_race_2023_answers-book.pdf | 21 | [
"NO CHOICES AVAILABLE"
] | 6.404 mol dm-3 | Ionic liquids are compounds which, despite being made up of ions, have a melting point below room temperature. They are a recent area of interest in chemical research, with applications in battery technology and large-scale chemical processing. One example of an ionic liquid is [Emim]+ acetate (ethanoate). The structur... |
https://www.mit.edu/~anugrah/files/MockIChOSolutions.pdf | 6 | [
"\"free response\""
] | "η_NKT-19 = 447%, η_Ideal = 550%" | Compute the refrigerator efficiencies of the NKT-19 refrigerator and that of a maximally efficient heat pump refrigerator operating between 270 K and 330 K. The heat transfer is simply equal to 0.90 ΔΗ = 29.83 kJ. The work was found earlier to be 6.672 kJ. Thus, efficiency = 29.83/6.672. Ideal efficiency = 1/(1-TC/TH).... |
http://chemistryrace.com/wp-content/uploads/2023/02/chemistry_race_2023_answers-book.pdf | 24 | [
"NO CHOICES AVAILABLE"
] | P4 + 10 CuSO4 + 16 H2O → 10 Cu + 10 H2SO4 + 4H3PO4 | Here is the text extraction from the PDF, with the requested formatting:
Copper ions are reduced to copper metal and phosphorus is oxidized. In this way, the phosphorus is covered by a copper layer and cannot continue to burn. Write a balanced chemical equation for the reaction that takes place when copper sulfate sol... |
http://chemistryrace.com/wp-content/uploads/2024/02/ChR_2024_answer_booklet.pdf | 21 | [
"NO CHOICES AVAILABLE"
] | 69 years | Uranium-232 is an artificially prepared isotope of uranium. Experimental measurements of a 1 gram sample of this radionuclide revealed an activity A = 8.26 × 10^11 Bq (activity is defined as a number of radioactive decays per second). Radioactive decay is described by the following equation:
N(t) = No e^(-λt),
wher... |
https://www.mit.edu/~anugrah/files/MockIChOSolutions.pdf | 6 | [
"\"free response\""
] | "q_rem = -6.900 kJ, W_done = 1.724 kJ" | The gas must be cooled isobarically from X to Y before it begins condensing. Calculate the heat removed from the gas and work done on the gas during this step. At P = 10.57 and T = TH = 330 K, V = 2.596 L.
Calculate the heat removed from the gas and work done on the gas during the cooling process from point X to Y at... |
https://facultystaff.richmond.edu/~lrunyenj/bio201/04bio201%20exam%201%20key.pdf | 1 | [
"NO CHOICES AVAILABLE"
] | ADG, Adg, aDg, adg | Imagine an individual with the genotype AaDdgg, where each of these genes is on a different chromosome. What are the gametes formed by an individual with the genotype AaDdgg? |
http://chemistryrace.com/wp-content/uploads/2022/02/cambridge_chemistry_race_2022_answers.pdf | 3 | [
"NO CHOICES AVAILABLE"
] | carbon dioxide (CO2) | Vitamin C is probably the most used supplement for boosting immunity. It is usually sold in the form of pills or gelatin capsules. However, in our task, we will take a look at the fizzy tablet Celaskon (for making into a beverage). It contains: ascorbic acid, citric acid, sorbitol, sodium bicarbonate, lactose, orange a... |
https://www.ttcho.com/_files/ugd/988b76_01ceeff230b24cbbb0125b2bfa3f3475.pdf | 28 | [
"\"A. CO₂\"",
"\"B. COOH\"",
"\"C. H\"",
"\"D. CH₃\""
] | C is the correct answer | Reaction of a Grignard reagent with CO₂ (g) will yield a carboxylate salt. Subsequent addition of H⁺ (aq) results in a carboxylic acid. What is the identity of Compound C?
(A) CO₂
(B) COOH
(C) H
(D) CH₃ |
http://chemistryrace.com/wp-content/uploads/2025/02/ChR_2025_answer_booklet.pdf | 25 | [
"NO CHOICES AVAILABLE"
] | The approximate change of Gibbs free energy for the isomerization of E-azobenzene to Z-azobenzene is 61.91 kJ mol¯¹. | Azobenzene is a well-known molecule and the parent structure of various molecular switches. The switching mechanism consists of a photochemically induced change in the double bond conformation from E- to Z- and vice versa. The wavelength of light necessary for the transformation of E-azobenzene to Z-azobenzene is 365 n... |
https://www.ttcho.com/_files/ugd/988b76_ba0cb3177d05436da273a400a037ed01.pdf | 27 | [
"NO CHOICES AVAILABLE"
] | "0.001 moldm³" | From Figure 2, this occurs when the pH = 11.0. The highest rate of hydrolysis occurs when there is the greatest change in concentration of carbaryl over the period of monitoring.
Calculate the [OH] at which there is the highest rate of hydrolysis of carbaryl. |
http://chemistryrace.com/wp-content/uploads/2025/02/ChR_2025_answer_booklet.pdf | 26 | [
"NO CHOICES AVAILABLE"
] | "61.91 kJ mol¯¹." | Azobenzene is a well-known molecule and the parent structure of various molecular switches. The switching mechanism consists of a photochemically induced change in the double bond conformation from E- to Z- and vice versa. The wavelength of light necessary for the transformation of E-azobenzene to Z-azobenzene is 365 n... |
http://chemistryrace.com/wp-content/uploads/2023/02/chemistry_race_2023_answers-book.pdf | 29 | [
"NO CHOICES AVAILABLE"
] | 90 | How many sigma bonds are there in the C₆₀ fullerene (a fullerene containing 60 carbon atoms)? |
https://www.mit.edu/~anugrah/files/MockIChOSolutions.pdf | 10 | [
"NO CHOICES AVAILABLE"
] | 0.340 V vs. SCE | In the beaker with 30 mmol added KI, the overall reaction is given by Cu2+ + 2I- → CuI + ½ I2. After the addition of KI, the dominant species are I₂ and I⁻, with concentrations of 5 mM and 10 mM, respectively. These concentrations can be plugged into the Nernst equation to determine the voltage.
What is the voltage r... |
http://chemistryrace.com/wp-content/uploads/2024/02/ChR_2024_answer_booklet.pdf | 33 | [
"NO CHOICES AVAILABLE"
] | Methane and t-butyl cation. | Carborane acids are a family of the strongest known acids to be made: they can readily protonate hydrocarbons. This is because the carborane counterion is exceptionally stable. While carborane acids are an excellent donor of H⁺, the molecule Me(CHB₁₁Me₅Br₆), known affectionately as 'mighty methyl', is a ready source of... |
http://chemistryrace.com/wp-content/uploads/2025/02/ChR_2025_answer_booklet.pdf | 38 | [
"\"free response\""
] | "42 mM" | If a person consumes enough lactose such that its reaction velocity, v, with lactase-phlorizin hydrolase is exactly two-thirds of the maximum, Vmax, and given that the Michaelis constant, KM, for lactase-phlorizin hydrolase is 21 mM, what concentration of lactose [S] was digested, in mM? |
https://www.mit.edu/~anugrah/files/MockIChOSolutions.pdf | 11 | [
"\"free response\""
] | "0.460 V" | This is before the equivalence point. Since the reaction goes to completion, [I2] can be considered to be ≈2.5 mM and [Cu2+] ≈ 5 mM. Calculate the voltage read by the indicator electrode in the beaker with 10 mmol added KI. |
http://chemistryrace.com/wp-content/uploads/2023/02/chemistry_race_2023_answers-book.pdf | 30 | [
"NO CHOICES AVAILABLE"
] | 5.816 × 10-34 Js | A laser pulse was used to irradiate a silicon monocrystal, evaporating 3.5 × 10^17 silicon atoms (estimated by spectroscopic measurements). The laser beam has a wavelength of 200 nm and delivers 2 × 10^17 photons in a single short pulse. The enthalpy of evaporation of silicon is 300 kJ mol−1. Work out the value of the ... |
https://www.ttcho.com/_files/ugd/988b76_e3d21fc42bb24de4959d7250f0cfcb3a.pdf | 18 | [
"\"A. 0\"",
"\"B. + 2\"",
"\"C. - 2\"",
"\"D. + 7\""
] | D is the correct answer. | KMnO4/H⁺ is slowly added to compound A. The oxidation numbers of: K = +1; O = -2. KMnO4 is a neutral compound, and therefore the sum of all charges of individual atoms present in its structure must be equal to 0: (1 x K) + (1 x Mn) + (4 x O) = 0; (1 x +1) + (1 x Mn) + (4 x -2) = 0. Mn = +7. What is the oxidation number... |
https://www.ttcho.com/_files/ugd/988b76_01ceeff230b24cbbb0125b2bfa3f3475.pdf | 22 | [
"\"A: Kc is only affected by temperature and the alcohol is a reactant, adding more of it will favour product formation\"",
"\"B: I is true and II is true\"",
"\"C: III is true\"",
"\"D: IV is true\""
] | A is the correct answer | When considering the effects of changing conditions on an equilibrium reaction, it's important to remember that Kc is only affected by temperature. The equilibrium position is influenced by the concentration of reactants and products. In this case, adding more alcohol, which is a reactant, will favor the formation of p... |
https://www.ttcho.com/_files/ugd/988b76_ba0cb3177d05436da273a400a037ed01.pdf | 6 | [
"\"SO2\""
] | SO2 | Chalcopyrite is a naturally occurring mineral with the formula: CuFeS2. Copper metal can be extracted by the complete open air combustion of Chalcopyrite in the presence of silica. The other products of this reaction are: ferrosilite (FeSiO3) and a colourless gas with a suffocating odour. The gas produced reacts with N... |
https://www.ttcho.com/_files/ugd/988b76_01ceeff230b24cbbb0125b2bfa3f3475.pdf | 34 | [
"\"A: 2\"",
"\"B: 3\"",
"\"C: 4\"",
"\"D: 6\""
] | "B is the correct answer" | Nuclear Magnetic Resonance (NMR) Spectroscopy is a powerful tool for the structural elucidation of unknown compounds. In 'H NMR, protons which have identical chemical (and magnetic) properties will appear as a single peak in the NMR spectra. Consider the structure of ethanol; there are three distinct groups of protons ... |
http://chemistryrace.com/wp-content/uploads/2023/02/chemistry_race_2023_answers-book.pdf | 37 | [
"NO CHOICES AVAILABLE"
] | 1.12% | Consider a quantitative synthetic pathway to make an L-polypeptide that is 100 amino acids long. The polypeptide should contain a glycine at the 1st, 10th, 23rd, and 58th place. If each step is performed without purification and diastereoisomer separation, what is the maximum allowed percentage of D-enantiomer contamin... |
https://www.ttcho.com/_files/ugd/988b76_ba0cb3177d05436da273a400a037ed01.pdf | 28 | [
"NO CHOICES AVAILABLE"
] | 2 | The true rate equation can be written as: rate = kB[OH][carbaryl], where kB = base-mediated hydrolysis rate constant. For the general rate equation: Rate = k[A][B][C]. Overall order = a + b + c. What is the overall order of this reaction? (1 mark) |
https://www.ttcho.com/_files/ugd/988b76_01ceeff230b24cbbb0125b2bfa3f3475.pdf | 22 | [
"\"A: Incomplete yield\"",
"\"B: Two products formed\"",
"\"C: Complete yield\"",
"\"D: Unpredictable yield\""
] | C is the correct answer | TLC is a useful method for following the progress of a reaction. You perform a reaction, and the TLC plate is shown below, where S = Starting material, R = Reaction mixture, C = Co-spot i.e. both the starting material and reaction mixture have been spotted here. Consider the reaction mixture lane: no starting material ... |
https://www.mit.edu/~anugrah/files/MockIChOSolutions.pdf | 13 | [
"NO CHOICES AVAILABLE"
] | 1. O-B-O⁻; 2. O-Si-O⁻; 3. O=P-O⁻ | Many cyclic oxyanions are known. Draw 3 examples, each based on a different group of the periodic table. |
https://www.mit.edu/~anugrah/files/MockIChOSolutions.pdf | 17 | [
"\"free response\""
] | "free response answer" | Ammonium chloride is both an acid and a source of chloride. The ammonium is a source of acid, which makes dichromate a stronger reducing agent, as well as producing H2. The chloride precipitates the Pb2+ formed, preventing it from interfering with the titration with tungsten (if for example it was oxidized). Propose a ... |
https://www.ttcho.com/_files/ugd/988b76_01ceeff230b24cbbb0125b2bfa3f3475.pdf | 30 | [
"\"A: A polyalkene formed via an addition process\"",
"\"B: A polyamide formed via an addition process\"",
"\"C: A polyalkene formed via a substitution process\"",
"\"D: A polyamide formed via a condensation process\""
] | D is the correct answer | Here's the text extraction:
<bold>49. Examine the structure of the polymer shown below:</bold>
<highlighted>Which of the following accurately describes it?</highlighted>
(A). A polyalkene formed via an addition process
(B). A polyamide formed via an addition process
(C). A polyalkene formed via a substitution proc... |
http://chemistryrace.com/wp-content/uploads/2024/02/ChR_2024_answer_booklet.pdf | 5 | [
"\"free response\""
] | "1960000 kg of bananas" | A kilogram of bananas produces on average 2.6 microliters of ethylene per hour at a temperature of 15°C. If Vlado wants to get a kilogram of ethylene per week, he needs to buy a certain amount of bananas, ignoring the respiration of bananas and other disturbing phenomena. How many kilograms of bananas does Vlado need t... |
http://chemistryrace.com/wp-content/uploads/2022/02/cambridge_chemistry_race_2022_answers.pdf | 56 | [
"NO CHOICES AVAILABLE"
] | E2 = 0.99 V. | Electrochemical methods are useful for measurements of various thermodynamic data. They take advantage of the principle of redox reactions i.e., exchange of electrons, and the fact that when conveniently arranged, these reactions can become a source of voltage. The 'willingness' of a compound to be reduced can then be ... |
https://www.ttcho.com/_files/ugd/988b76_e3d21fc42bb24de4959d7250f0cfcb3a.pdf | 21 | [
"\"A. C4H9COOH and C3H8O3\"",
"\"B. C4H9COONa⁺ and C3H8O3\"",
"\"C. C4H9OH and C3H8O3\"",
"\"D. C4H9 and C3H8O3\""
] | B. C4H9COONa⁺ and C3H8O3 | Compound D shown below undergoes saponification with NaOH (aq) / Δ.
C4H9
CH2
CH
C
H2C
C4H9
C4H9
D
What are the product(s) of this reaction?
(A). C4H9COOH and C3H8O3
(B). C4H9COONa⁺ and C3H8O3
(C). C4H9OH and C3H8O3
(D). C4H9 and C3H8O3 |
https://www.ttcho.com/_files/ugd/988b76_ba0cb3177d05436da273a400a037ed01.pdf | 18 | [
"NO CHOICES AVAILABLE"
] | D = K2CO3 (give marks for any base that is suggested) | Phenacetin (shown below), can be obtained from paracetamol in a single step using ethyl iodide and reagent D. Consider the structure of both reactants and determine what change they have undergone in forming a single product: Paracetamol loses an H⁺; and ethyl iodide loses an I. i.e. HI is produced. What will neutraliz... |
https://www.usabo-trc.org/sites/default/files/images/pdf/exams/semifinal-answers/2011-semifinal-answers.pdf | 43 | [
"\"free response\""
] | "free response answer" | Gametophytes are much reduced in angiosperms. A major advance is the evolution of pollen. The pollen grain falls on the stigma, and a pollen tube grows down the style and delivers 2 sperm directly to the embryo sac—there is no need for flagellated sperm. Double fertilization gives rise to a zygote and triploid endosper... |
https://www.mit.edu/~anugrah/files/MockIChOSolutions.pdf | 4 | [
"NO CHOICES AVAILABLE"
] | 10.57 bar | Use the Clausius-Clapeyron equation. ln(P/1 bar) = -ΔΗ/R (1/330 - 1/276.1).
What is the vapor pressure of the coolant at T H? |
http://chemistryrace.com/wp-content/uploads/2024/02/ChR_2024_answer_booklet.pdf | 36 | [
"\"free response\""
] | "8" | Nepetalactone is an organic substance belonging to the group of lactones found in plants of the genus *Nepeta*, known as catnip. This substance acts like a sex pheromone on cats, which is why many cats respond so intensely to catnip. Each chiral centre in a molecule gives rise to two possible epimers (stereoisomers whi... |
https://www.mit.edu/~anugrah/files/MockIChOSolutions.pdf | 10 | [
"\"2Cu2+ + 4I- → 2CuI + I2\"",
"\"2Cu2+ + 5I → 2CuI + I3\""
] | Either of "2Cu2+ + 4I- → 2CuI + I2" or "2Cu2+ + 5I → 2CuI + I3" | Here's the extracted text, with formatting:
Here's the extracted text, with formatting: In the context of the reaction involving copper ions and iodide ions, the balanced equation for the reaction of Cu2+ and I- can be expressed as:
- 2Cu2+ + 4I- → 2CuI + I2
or
- 2Cu2+ + 5I- → 2CuI + I3.
What is the balanced equati... |
http://chemistryrace.com/wp-content/uploads/2022/02/cambridge_chemistry_race_2022_answers.pdf | 59 | [
"\"free response\""
] | "free response answer" | Summary (molecular) formulae quite often gives sufficient information about inorganic compounds. Organic compounds, on the other hand, cannot be easily described just by a summary formula; hundreds of isomers can exist for a given summary formula, so knowing the structure of the molecule is important. Fortunately, orga... |
http://chemistryrace.com/wp-content/uploads/2024/02/ChR_2024_answer_booklet.pdf | 35 | [
"NO CHOICES AVAILABLE"
] | approximately 15 CZK | At Popeye's favourite petrol station, 1 litre of petrol costs 39.89 CZK. The density of petrol at 2°C is 755 kg/m³. Assume that the petrol is in thermal equilibrium with the surrounding air. The thermal expansion of gasoline is 1.20 × 10^-3 K^-1. Thermal expansion indicates the percentage by which a substance increases... |
https://www.mit.edu/~anugrah/files/MockIChOSolutions.pdf | 4 | [
"\"A: P < Pext",
"B: P = Pext",
"C: P > Pext\""
] | B: P = Pext | Which of the following should be true of a reversible process? (Choose one)
1. ☐ P < Pext
2. ☐ P = Pext - This is the answer
3. ☐ P > Pext
|
https://www.ttcho.com/_files/ugd/988b76_e3d21fc42bb24de4959d7250f0cfcb3a.pdf | 16 | [
"\"A: 1\"",
"\"B: 2\"",
"\"C: 3\"",
"\"D: 4\""
] | B is the correct answer. | Considering the homologous series of alkanes, arrange the following compounds in order of increasing boiling point:
(A). CH4 < C3H8 < C7H16 < C8H18
(B). C8H18 < C7H16 < C3H8 < CH4
(C). CH4 < C7H16 < C3H8 < C8H18
(D). C8H18 < C3H8 < C7H16 < CH4
Structural isomerism is distinct from stereoisomerism. One approac... |
http://chemistryrace.com/wp-content/uploads/2025/02/ChR_2025_answer_booklet.pdf | 18 | [
"NO CHOICES AVAILABLE"
] | M = 92.149 (average molar mass) | The label on one of the bottles in your lab's chemical cabinet has fallen apart after being stored for a long time, and now you don't know what substance is in it. Unfortunately, you have been underfunded for a long time and therefore do not have access to NMR or GC-MS/LC-MS analysis. However, you have found an older a... |
http://chemistryrace.com/wp-content/uploads/2023/02/chemistry_race_2023_answers-book.pdf | 7 | [
"NO CHOICES AVAILABLE"
] | F-H-F, bond angle 180 degrees. | The bifluoride anion, [HF2]¯, is intriguing because its bonding is not well described using conventional ionic or covalent valence bond models. Draw the structure of the bifluoride anion, including the bond angle at the central atom. What is the structure of the bifluoride anion [HF2]¯, including the bond angle at the ... |
https://www.mit.edu/~anugrah/files/MockIChOSolutions.pdf | 17 | [
"\"free response\""
] | "Ñ(O-D, DOAc) = 2037.3 cm¯¹, Ñ(O-D, D3O+) = 2182.8 cm¯¹" | * <bold>3. Calculate the stretching frequency of the O-D bond in DOAc and D3O⁺, respectively.</bold>
* <bold>✓ is proportional to sqrt(1/mu), and we may assume force constants don't change with isotopic substitution.</bold>
* <bold>Ñ(O-D, DOAc) = ỹ(O-H, HOAc)*sqrt(.94118/1.7778) = 2037.3 cm¯¹</bold>
* <bold>Ñ(O... |
http://chemistryrace.com/wp-content/uploads/2024/02/ChR_2024_answer_booklet.pdf | 8 | [
"NO CHOICES AVAILABLE"
] | 9.875 × 10^-3 gcm^-3 | Let us further assume that tellurium hexafluoride behaves as an ideal gas. What is its density at 25°C and a pressure of 101 325 Pa, assuming it behaves as an ideal gas? |
https://www.usabo-trc.org/sites/default/files/images/pdf/exams/semifinal-answers/2011-semifinal-answers.pdf | 43 | [
"\"free response\""
] | "free response answer" | Life cycle altered to avoid necessity of flagellated sperm swimming to egg and to provide protection for embryo. Any six of the following: Gametophytes are much reduced in angiosperms; Major advance is evolution of pollen; Pollen grain falls on stigma and pollen tube grows down style and delivers 2 sperm directly to em... |
http://chemistryrace.com/wp-content/uploads/2021/02/Chemistry_Race_2021_Questions_and_Solutions.pdf | 37 | [
"\"free response\""
] | "water and carbon dioxide" | Chemist Victor carried out a similar reaction, where phenylmagnesium bromide reacts with oxygen, resulting in the formation of the corresponding phenolate:
Ph-MgBr + O2 → Ph-O¯ + Mg2+ + Br¯
Since he was too lazy to bubble oxygen through the etheric solution, he instead used the setting as in the reaction with dry i... |
https://www.mit.edu/~anugrah/files/MockIChOSolutions.pdf | 18 | [
"NO CHOICES AVAILABLE"
] | Rate = k[H⁺][K], k = 1.1527*10² M-¹h-¹ | First order in [H]⁺, first order in [K], zeroth order in [Br₂].
Rate = k[H⁺][K], k = 1.1527*10² M⁻¹h⁻¹.
Determine the rate law and rate constant for this reaction. |
https://www.mit.edu/~anugrah/files/MockIChOSolutions.pdf | 5 | [
"NO CHOICES AVAILABLE"
] | Wdone = 2.020 kJ, qads = 29.83 kJ | The piston then expands isothermally and reversibly until all the liquid is vaporized, removing heat from the refrigerator. How much work is done by the expanding gas, and how much heat is absorbed during the isothermal expansion of the piston? |
https://www.ttcho.com/_files/ugd/988b76_e3d21fc42bb24de4959d7250f0cfcb3a.pdf | 23 | [
"\"A. No reaction\"",
"\"B. Addition of hydrogen chloride\"",
"\"C. Addition of chlorine\"",
"\"D. Substitution of a chlorine atom for a hydrogen atom\""
] | "C is the correct answer." | Cyclohexene is reacted with chlorine gas at RT in the dark. Alkenes possess a double bond, which is comprised of a π bond and a σ (single) bond. A π bond is much weaker, and therefore more reactive, than a σ bond. Via their π bond, alkenes can therefore undergo reaction with halogens to yield a dihalide. Which of the f... |
http://chemistryrace.com/wp-content/uploads/2024/02/ChR_2024_answer_booklet.pdf | 23 | [
"\"free response\""
] | "10 P2I4 + 13 P4 + 128 H2O → 40 PH4I + 32 H3PO4." | Phosphonium iodide (PH4I) is analogous to more known ammonium chloride. It is a stable and convenient source of phosphane (which is released after its reaction with a base) and can be used for incorporating phosphorus into organic molecules. Phosphonium iodide can be prepared by reaction of diphosphine tetraiodide (P2I... |
https://www.mit.edu/~anugrah/files/MockIChOSolutions.pdf | 5 | [
"NO CHOICES AVAILABLE"
] | Pvap = 10.57 bar | At P = 10.57 and T = TH = 330 K, V = 2.596 L. Use the Clausius-Clapeyron equation. ln(P/1 bar) = -ΔΗ/R (1/330 - 1/276.1). What is the vapor pressure of the coolant at TH? |
https://www.ttcho.com/_files/ugd/988b76_e3d21fc42bb24de4959d7250f0cfcb3a.pdf | 12 | [
"\"A. Chlorine-35 and Chlorine-37\"",
"\"B. Na and Li\"",
"\"C. Red phosphorus and white phosphorus\"",
"\"D. Na and Mg\""
] | C is the correct answer. | Allotropes are the different forms of the same element, in a given physical state. Here are some pairs of substances to consider:
**(A). Chlorine-35 and Chlorine-37**
**(B). Na and Li**
**(C). Red phosphorus and white phosphorus**
**(D). Na and Mg**
Which of the following pairs of substances are allotropes? |
http://chemistryrace.com/wp-content/uploads/2025/02/ChR_2025_answer_booklet.pdf | 11 | [
"NO CHOICES AVAILABLE"
] | magnesium chloride, sodium chloride, potassium iodide | Regardless of your level of Swedish language proficiency, you most likely noticed the mentions of magnesium chloride, sodium chloride, and potassium iodide. Let's ignore those inorganic salts for now, and focus on the last verse in the excerpt instead. The sea is green, dark absinthe green, it is bitter like magnesium ... |
https://www.mit.edu/~anugrah/files/MockIChOSolutions.pdf | 4 | [
"NO CHOICES AVAILABLE"
] | Wdone = 2.020 kJ, qads = 29.83 kJ | The piston then expands isothermally and reversibly until all the liquid is vaporized, removing heat from the refrigerator. How much work is done by the expanding gas, and how much heat is absorbed? |
http://chemistryrace.com/wp-content/uploads/2025/02/ChR_2025_answer_booklet.pdf | 26 | [
"NO CHOICES AVAILABLE"
] | "4." | The octet rule is an empirical tool that helps us determine which molecules are likely to exist and which are not. According to the octet rule, a molecule is considered stable if all its atoms have eight electrons (or two, in the case of hydrogen) in their extended vicinity. But what does "extended vicinity" mean? It i... |
https://www.ttcho.com/_files/ugd/988b76_e3d21fc42bb24de4959d7250f0cfcb3a.pdf | 23 | [
"\"A. C3H7OH\"",
"\"B. C2H6\"",
"\"C. CH3COOH\"",
"\"D. HO\""
] | "D is the correct answer." | Fermentation is the anaerobic reaction (absence of oxygen) of carbohydrates (glucose, fructose, sucrose) to yield ethanol and carbon dioxide. Options (A) - (C) are invalid.
Which of the following compounds, when fermented, will yield ethanol?
(A). C3H7OH
(B). C2H6
(C). CH3COOH
(D). HO
HO
OH
OH |
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