Chemical combination - Jamb Chemistry Past Questions and Answers

Question 26:

• 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

Question 27:

• JAMB 1983

Zn + H₂ SO₄ → ZnSO₄ + H₂
in the above reaction how much zinc will be left of 1.0 M of H₂SO?
[Zn =65, s = 32, O = 16, H = 1]

A. 1.35g
B. 1.00g
C. 0.70g
D. 0.65g
E. 0.00g

Question 28:

• JAMB 1984

20 cm ³ of hydrogen gas are sparked with 20cm ³ of oxygen gas in an endimoeter at 373k (100 ^oC) and 1 atmosphere. The resulting mixture is cooled to 298 K (25 ^oC) and passed over calcium chloride. The volume of the residual gas is

A. 40 cm ³
B. 20 cm ³
C. 30 cm ³
D. 10cm ³
E. 5cm ³

Question 29:

• JAMB 1984

For the reaction NH4NO2 \(\to\) N2 + 2H2O, calculate the volume of nitrogen that would be produced at S. T. P from 3.2 g of the dioxonitrate(iii)salt. (Relative atomic masses: N = 14, O = 16, H = 1)

A. 2.24 dm ³
B. 2.24 cm³
C. 1. 12³
D. 1. 12dm ³
E. 4. 48 dm ³

Question 30:

• JAMB 1984

A molar solution of caustic soda is prepared by dissolving

A. 40 g NaOH in 100 g of water
B. 40 g NaOH in 1000 g of water
C. 20 g NaOH in 500 of solution
D. 20 g NaOH in 1000 g of solution
E. 2o g NaOH in 80 g of solution