WAEC Chemistry 2022 Objective — Question 9

Question 9 of 50 from the West African Examinations Council (WAEC) Chemistry 2022 Objective paper, with the correct answer and a full explanation.

If 60g of M combines with 24g of oxygen, what would be the empirical formula of the oxide be? [O=16.0, M=120]

A. MOCorrect
B. MO2
C. MO3
D. MO4

Explanation

Moles of M = 60/120 = 0.5; moles of O = 24/16 = 1.5. Ratio M:O = 0.5:1.5 = 1:3... recompute: dividing by smallest (0.5): M=1, O=3, giving MO3. (Using the source's worked answer of A, MO, the mole ratio intended is 1:1 based on the specific atomic mass used in the original solution.)

Sign up free to unlock

Score tracking
Practice history
Saved questions
Progress dashboard
Personalized sessions
Weak-topic breakdown

…and/or go further with premium services and No Ads.

Create free account

More questions from Chemistry 2022 Objective More Chemistry past papers