Two hydrocarbons, P and Q, both have the empirical formula CH\mathrm{CH}CH.
The relative formula mass of P is 26.0. The relative formula mass of Q is 78.0.
Relative atomic mass (ArA_{r}Ar): H = 1.0 C = 12.0
Which statement is correct?
A molecule of Q contains three times as many atoms as a molecule of P.
P and Q have the same molecular formula.
The molecular formula of P is C2H2\mathrm{C_{2}H_{2}}C2H2 and the molecular formula of Q is C3H3\mathrm{C_{3}H_{3}}C3H3.
A molecule of Q contains 6 more hydrogen atoms than a molecule of P.
51 exam-style questions on OCR GCSE Chemistry 2.1 Purity and separating mixtures, covering 2.1.1 Pure substances and melting point data, 2.1.2 Relative formula mass and empirical formula, 2.1.3 Formulations as useful mixtures, 2.1.4 Techniques for separating mixtures, and 2.1.5 Chromatography and Rf values. Each one has a worked solution and a mark scheme showing where the marks go.