Chemical combination - Jamb Chemistry Past Questions and Answers

Question 36:

• JAMB 1985

3.0g of a mixture of potassium carbonate and potassium chloride were dissolved in a 25cm³ of this solution required required 40.00cm₃ of 0.1M HCl for neutralization. What is the percentage by weight of K₂CO₃ in the mixture. (K = 39, O = 16, C = 12)

A. 60
B. 72
C. 82
D. 89
E. 92

Question 37:

• JAMB 1986

What mass of a divalent metal M (atomic mass = 40) would react with excess hydrogen gas measured at S.T.P?

A. 8.0 g
B. 4.0 g
C. 0.8 g
D. 0.4 g

Question 38:

• JAMB 1986

The number of atoms of chlorine present in 5.85g of NaCl is [Avogaro's Number = 6.02 x 10²³]

A. 6.02 x 10²²
B. 5.85 x 10²³
C. 6.02 x 10²³
D. 5.85 x 10²⁴

Question 39:

• JAMB 1986

How much of magnesium is required to react with 260cm³ of 0.5 M HCl? [Mg = 24]

A. 0.3g
B. 1.5g
C. 2.4g
D. 3.0g

Question 40:

• JAMB 1987

The solubility of Na₃AsO₄(H₂O)₁₂ is 38.9g per 100g H₂O. What is the mass percentage of Na₃AsO₄ in the saturated solution?
(As = 75, Na = 23, O = 16, H = 1)

A. 87.27%
B. 38.9%
C. 19.1%
D. 13.7%