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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 5 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 1.2 mol and has stated molar mass 129 g/mol. Find its mass. Round to 3 decimal places if needed. Answer in g.
g
2General chemistryFor the abstract reaction A + 2B → C, 23 mol A and 5 mol B are available. Assume complete consumption of the limiting reactant. Find the maximum amount of C. Round to 3 decimal places if needed. Answer in mol.
mol
3Chemical reactionsIn a sealed container, 10 g of A and 25.1 g of B react until B is used up. 9 g of A is left over, and the only product is C. What mass of C forms?
g
4Chemical reactionsBalance this equation using the smallest whole-number coefficients: __ P₄ + __ O₂ → __ P₄O₁₀. What is the coefficient of P₄?
5Acids, bases & pHA solution at 25 °C has a pH of 7.5. Is it acidic, neutral or basic?
6Acids, bases & pHHow many times greater is the hydrogen-ion concentration in a solution of pH 3 than in a solution of pH 7?
7Analytical chemistryA 40 g sample is 37% desired substance by mass. Find the desired substance mass. Round to 3 decimal places if needed. Answer in g.
g
8Analytical chemistryA supplied valid-range calibration is S = 13c + 0.7. The signal is 2.8. Find c in the calibration's arbitrary concentration units. Round to 3 decimal places if needed.
9Physical chemistryFor A ⇌ B, use Kc = [B]/[A]. Equilibrium concentrations are [A] = 2.3 and [B] = 2 mol/L. Find Kc. Round to 3 decimal places if needed.
10Physical chemistryFor one reaction as written, a bond model requires 675 kJ/mol to break bonds and releases 422 kJ/mol on forming bonds. Estimate ΔH. Round to 3 decimal places if needed. Answer in kJ/mol.
kJ/mol
11Organic chemistryIgnoring end groups in a supplied model, a polymer chain has 174 repeat units, each contributing 100 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 8 carbon atoms. In a complete-combustion model, all its carbon forms CO₂. How many moles of CO₂ come from 3.1 mol hydrocarbon? Round to 3 decimal places if needed. Answer in mol.
mol
13BiochemistryA simple unbranched, noncyclic peptide contains 157 amino-acid residues. How many peptide links connect adjacent residues? Round to 3 decimal places if needed.
14BiochemistryWhich feature is part of a nucleotide?

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 31 g solute and 171 g solvent. Find the solute mass percentage. Round to 3 decimal places if needed. Answer in %.
%
16Organic chemistry (Grade 11)How many carbon atoms are written in CH₃CH₂CH₃?