O-LevelChemistryStoichiometry5070/12 · May/June 2021 · Q101 Mark

The names and formulae of three nitrogen compounds are shown. ammonia NH3 hydrazine N2H4 hydroxylamine NH2OH Which compound has the highest relative molecular mass, Mr, and in which compound is the percentage by mass of hydrogen the greatest?

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Ahighest Mr: N2H4, greatest percentage by mass of hydrogen: NH3

Bhighest Mr: N2H4, greatest percentage by mass of hydrogen: N2H4

Chighest Mr: NH2OH, greatest percentage by mass of hydrogen: NH3

Dhighest Mr: NH2OH, greatest percentage by mass of hydrogen: N2H4

✓ Correct answer

C: highest Mr: NH2OH, greatest percentage by mass of hydrogen: NH3

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Topic: Stoichiometry, O-Level Chemistry (syllabus 5070). Multiple choice, 1 mark.
Source: O-Level Chemistry, May/June 2021 Paper 1 Variant 2, question 10.

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