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Grade 12 · Chemistry

Grade 12 Chemistry diagnostic

16 questions on general chemistry, chemical reactions, acids, bases & ph, analytical chemistry, physical chemistry, organic chemistry and biochemistry, plus 2 from Grade 11. Answer what you can, then check your answers to see which topics are secure and what to practise next.

16 questions7 topicsAbout 20 minutesSet 1 of 5

Skip a question if you do not know the answer. It is better than guessing, because it shows what to practise.

1General chemistryA sample contains 2.3 mol and has stated molar mass 43 g/mol. Find its mass. Round to 3 decimal places if needed. Answer in g.
g
2General chemistryA model sample has mass 109 g and stated molar mass 27 g/mol. Find its amount. Round to 3 decimal places if needed. Answer in mol.
mol
3Chemical reactionsBalance this equation using the smallest whole-number coefficients: __ Fe₂O₃ + __ CO → __ Fe + __ CO₂. What is the coefficient of Fe₂O₃?
4Chemical reactionsIn a sealed container, 21.2 g of substance A reacts completely with 21.7 g of substance B. The only product is substance C. What mass of C forms?
g
5Acids, bases & pHSolution X has pH 11 and solution Y has pH 9. Which is more basic?
6Acids, bases & pHHow many times greater is the hydrogen-ion concentration in a solution of pH 8 than in a solution of pH 10?
7Analytical chemistryA 20 mL aliquot at 0.2 mol/L is diluted to 140 mL total without reaction or loss. Find the final concentration. Round to 3 decimal places if needed. Answer in mol/L.
mol/L
8Analytical chemistryThe theoretical dry pure product mass is 50 g; the actual dry pure product mass is 1 g. Find percentage yield. Round to 3 decimal places if needed. Answer in %.
%
9Physical chemistryAn ideal gas has initial pressure 137 kPa and volume 8.2 L. At fixed amount and temperature its volume becomes 7.6 L. Find the new pressure. Round to 3 decimal places if needed. Answer in kPa.
kPa
10Physical chemistryThe given standard reduction potentials are 1.17 V for the cathode and -0.49 V for the anode. Find E°cell. Round to 3 decimal places if needed. Answer in V.
V
11Organic chemistryIgnoring end groups in a supplied model, a polymer chain has 253 repeat units, each contributing 28 g/mol to the chain molar mass. Estimate that mass. Round to 3 decimal places if needed. Answer in g/mol.
g/mol
12Organic chemistryA hydrocarbon molecule contains 3 carbon atoms. In a complete-combustion model, all its carbon forms CO₂. How many moles of CO₂ come from 3 mol hydrocarbon? Round to 3 decimal places if needed. Answer in mol.
mol
13BiochemistryA simple unbranched, noncyclic peptide contains 68 amino-acid residues. How many peptide links connect adjacent residues? Round to 3 decimal places if needed.
14BiochemistryWhat is a substrate?

From Grade 11

These questions check skills from the grade below, so gaps can be spotted early.

15Analytical chemistry (Grade 11)A model solution contains 5 g solute and 100 g solvent. Find the solute mass percentage. Round to 3 decimal places if needed. Answer in %.
%
16Organic chemistry (Grade 11)Which is conventionally treated as an inorganic carbon compound?