Atoms, ions, formulae and relative masses Quiz
Studying this course? Keep your progress in one place.
Pick an answer for each. Quizzes never use energy.
5 questions, one answer each
Each answer is checked as you go, with why.
See all 5 questions
1. Which is the correct relative formula mass of magnesium nitrate, Mg(NO3)2 (Mg 24.3, N 14.0, O 16.0)?
- A. 86.3
- B. 124.3
- C. 148.3
- D. 170.3
2. Which statement about relative atomic mass is correct?
- A. It is the mass of one atom in grams
- B. It has units of g mol-1
- C. It is a weighted mean mass compared with one twelfth of a carbon-12 atom
- D. It equals the mass number of the commonest isotope
3. A compound has empirical formula CH2O and relative molecular mass 180. What is its molecular formula (C 12.0, H 1.0, O 16.0)?
- A. CH2O
- B. C3H6O3
- C. C5H10O5
- D. C6H12O6
4. A gas is present at 350 ppm. What is this as a percentage?
- A. 0.35%
- B. 0.035%
- C. 3.5%
- D. 0.0035%
5. Why is sodium chloride described by relative formula mass, not relative molecular mass?
- A. It is a gas at room temperature
- B. It forms a giant ionic lattice with no discrete molecules
- C. It contains only two elements
- D. Its atoms have no mass