Chemical combination - Jamb Chemistry Past Questions and Answers

Question 31:

• JAMB 1984

The ratio of the number of molecules in 2g of hydrogen to that in 16g of oxygen is

A. 2:1
B. 1:1
C. 1:2
D. 1:4
E. 1:8

Question 32:

• JAMB 1984

The balanced equation for the reaction of tetraoxosulphate(VI)acid with aluminium hydroxide to give water and aluminium tetraoxosulphate(VI) is

A. H₂SO₄ + Al(OH)₂ \(\to\) 2H₂O + AlSO₄
B. 3H₂SO₄ + 2Al(OH)₃ \(\to\) 6H₂O + Al₂(SO₄)₃
C. 3H₂SO₄ + 2AlH \(\to\) 6H₂O + Al(SO₄)₃
D. 3H₂ SO₄ + 2Al(OH)₃ \(\to\) Al(SO₄)₃
E. H₂SO₄ + Al(OH)₃ \(\to\) H₂O + Al₂(SO₄)₃

Question 33:

• JAMB 1984

At S. T. P how many litres of hydrogen can be obtained from the reaction of 500 cm³ of 0.5 M H ₂SO ₄ with excess zinc metal?
(Gram molecular volume of H₂ = 22. 4 dm ³)

A. 22.4 dm ³
B. 11 . 2 dm ³
C. 6. 5 dm ³
D. 5. 6 dm ³
E. 0. 00 dm ³

Question 34:

• JAMB 1985

0.499g 0f CuSO₄.xH₂O when heated to constant weight gave a residue of 0.346g. the value of x is? (Cu = 63.5, S = 32.0, O = 16, H = 1)

A. 0.5
B. 2.0
C. 3.0
D. 4.0
E. 5.0

Question 35:

• JAMB 1985

Given that the molecular mass of iron is 56 and that of oxygen is 16, how many moles of iron(iii)oxide will be contained in 1kg of the compound?

A. 25.0 moles
B. 12.5 moless
C. 6.25 moles
D. 3.125 moles
E. 0.625 moles