Chemistry Practice Test – Mass-Volume Relationship In Reactions (Questions With Answers and Explanations)

Consider the reaction represented by the equation:

2NaHCO₃  Na₂CO₃ + H₂O + CO₂

What is the mass of sodium trioxocarbonate(IV) produced by the complete decomposition of 33.6 g of sodium hydrogen trioxocarbonate(IV)?

[NaHCO₃ = 84; Na₂CO₃ = 106] (WASSCE 2009)

A. 10.6 g  
B. 16.8 g 
C. 21.2 g  
D. 42.4 g

A small conical flask contains 72 g of petrol (C₈H₈). How many molecules of petrol are there in the flask? (C = 12, H = 1; Avogadro’s constant = 6.02 x 10²³)

A. 0.632 mol       
B. 1.14 x 10²³ mol       
C. 3.80 x 10²⁰ mol       
D. 3.80 x 10²³ mol

What is the volume occupied by 2 moles of ammonia at s.t.p? (WASSCE 2010)

A. 44.8 dm³   
B. 22.4 dm³  
C. 11.2 dm³  
D. 5.6 dm³