Stoichiometry - Chemistry Jamb Past Questions and Answers

Question 21 :

• JAMB 1982

An element X has two isotopes, ²⁰₁₀X and ²⁰₁₀X,
present in the ratio 1:3. The relative atomic mass of X would be?

A. 20.5
B. 21.0
C. 21.5
D. 22.0
E. 22.5

Question 22 :

• JAMB 1982

What weight of sodium hydroxide is required to make 500 cm³ of 0.2 M solution?
(Na = 23, O = 16, H = 1)

A. 40 g
B. 20 g
C. 10 g
D. 4 g
E. 2 g

Question 23 :

• JAMB 1982

The number of grammes of potassium hydroxide in 250cm³ of one molar solution is?
(K = 39, O = 16, H = 1)

A. 40g
B. 52g
C. 100g
D. 26g
E. 14g

Question 24 :

• JAMB 1982

60cm³ of hydrogen are sparked with 20cm³ of oxygen at 100°C and 1 atmosphere. The total volume of the residual gases is?

A. 60 cm³
B. 10 cm³
C. 40 cm³
D. 30 cm³
E. 70 cm³

Question 25 :

• JAMB 1983

Some copper (ll) sulphate pentahydrate (CuSO₄ 5H₂O), was heated at 120 ^oC with the following results. Wt of crucible = 10.00 g; Wt of crucible + CuSO₄ 5H₂O =14.98g; Wt of crucible + residue = 13.54 g. How many molecules of water of crystalization were lost?
[H = 1, Cu = 63.5, O = 16, S = 32]

A. 1
B. 2
C. 3
D. 4
E. 5