QCE Chemistry Paper 1 free practice questions with answers
Read question 1 and its full worked answer from paper 1 of our 20-paper QCE Chemistry Paper 1 set, then download the 4-page PDF. These are original practice questions, not official past papers. Page updated 3 November 2026.
0.54 mol of H₂ and 0.54 mol of I₂ are placed in a 1.00 L flask at a temperature where Kc
= 9.00 for H₂ + I₂
2HI. What is the equilibrium concentration of HI?
A 0.648 mol L−¹
B 0.216 mol L−¹
C 0.324 mol L−¹
D 1.30 mol L−¹
Correct answer: A — 0.648 mol L−¹
- ICE table: change in [H₂] = −x, [I₂] = −x, [HI] = +2x.
- Kc = (2x)² ÷ [(0.54 − x)(0.54 − x)] = 9.00.
- Take the square root of both sides: 2x ÷ (0.54 − x) = 3.00, so x = 0.324 mol L−¹.
- [HI] = 2x = 0.648 mol L−¹
- Why the other options are wrong:
- B (0.216 mol L−¹): gave the [H₂] left over
- C (0.324 mol L−¹): gave x instead of 2x
- D (1.30 mol L−¹): doubled 2x
ICE tables: Initial, Change, Equilibrium. When the expression is a perfect square (equal reactant amounts, Δn = 0) take the square root of both sides to avoid a quadratic.
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Questions about this sample
What is in the QCE Chemistry Paper 1 free sample?
The first 3 questions from paper 1 of the set, in the real exam layout, followed by the step-by-step worked answers. It is a 4-page PDF; this page shows question 1 with its answer.
How many full QCE Chemistry Paper 1 papers are there?
20 original papers for Queensland Year 12 students (QCE). Each is a 58-mark paper with Section I 20 multiple-choice, Section II 38 marks, 10 minutes perusal and 90 minutes working time, with a worked solution for every question. Papers start at A$15.99 and download instantly as a PDF.
Are these official past papers?
No. The sample is taken from our own original practice paper and is not an official past paper or affiliated with any exam authority.