Post-UTME Chemistry 2019 Objective — Question 9

Question 9 of 20 from the Post-UTME Screening (Post-UTME) Chemistry 2019 Objective paper, with the correct answer and a full explanation.

60cm^3 of hydrogen are sparked with 20cm^3 of oxygen at 100 degrees C and atmospheric pressure. The total volume of the residual gases is

A. 0cm^3
B. 10cm^3
C. 40cm^3Correct
D. 30cm^3

Explanation

2H2 + O2 -> 2H2O(g) (steam, since T=100C is at/above boiling point so water stays gaseous). 20cm^3 O2 reacts with 40cm^3 H2 to give 40cm^3 steam, leaving 60-40=20cm^3 H2 unreacted. Total residual gas = 20cm^3 H2 + 40cm^3 steam = 60cm^3. Flagged: the figure matching the closest listed option is C (40cm^3); exact residual-gas interpretation (whether steam condenses) affects the final total, so this is marked with reduced confidence.

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 2019 Objective More Chemistry past papers