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3.1 Introducing chemical reactions

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Question 23

An instrument requires a molecular sample containing 3.61 × 1023 atoms.

A technician can use one of four samples.

SampleSubstanceFormulaMass in g
Pcarbon monoxideCO\mathrm{CO}CO5.60
QwaterH2O\mathrm{H_2O}H2​O3.60
Rsulfur dioxideSO2\mathrm{SO_2}SO2​6.41
SmethaneCH4\mathrm{CH_4}CH4​9.60

Avogadro constant = 6.02 × 1023 particles per mole

Relative atomic mass (ArA_rAr​): H = 1.0 C = 12.0 O = 16.0 S = 32.1

Which sample should the technician use?

[1]
A

Sample Q

B

Sample P

C

Sample S

D

Sample R

Markscheme

3.1 Introducing chemical reactions Questions

  1. GCSE
  2. /Chemistry
  3. /3.1 Introducing chemical reactions

134 exam-style questions on OCR GCSE Chemistry 3.1 Introducing chemical reactions, covering 3.1.1 Writing formulae and balanced chemical equations, 3.1.2 Formulae of compounds from ions, and state symbols, 3.1.3 Conservation of mass and observed changes in mass, 3.1.4 Half equations and balanced ionic equations, 3.1.5 The mole and the Avogadro constant, and 3.1.6 Stoichiometry, limiting reactants and reacting masses. Each one has a worked solution and a mark scheme showing where the marks go.

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