Chemical combination - Jamb Chemistry Past Questions and Answers

Question 81:

• JAMB 1997

Use the graph above to answer this question. A sample, X, solid at room temperature, was melted, heated to a temperature of 358 K and allowed to cool as shown in OPQR. The section PQ indicates that X is

A. A mixture of salts
B. A hydrated salt
C. An ionic salt
D. A pure compound

Question 82:

• JAMB 1998

A given amount of gas occupies 10.0 dm³ at atm, and 273°C. The number of moles of the gas present is?
(Molar volume of a gas at s.t.p. = 22.4 dm³)

A. 0.89 mol
B. 1.90 mol
C. 3.80 mol
D. 5.70 mol

Question 83:

• JAMB 1998

C₃H_8(g) + 50_2(g) → 4H₂O + 3CO_2(g). Form the equation above the volume of oxygen at s.t.p. required to burn 50cm³ of propane is?

A. 250 cm³
B. 150 cm³
C. 100 cm ³
D. 50 cm³

Question 84:

• JAMB 1998

30cm³ of hydrogen was collected over water at 27°C and 780 mm Hg. If the vapour pressure of water at the temperature of the experiment was 10 mm Hg, calculate the volume of the gas at 760 mm Hg and 7°C?

A. 40.0 cm³
B. 35.7 cm³
C. 28.4 cm³
D. 25.2 cm³

Question 85:

• JAMB 1998

The line observed in the sample hydrogen spectrum are due to emission of?

A. Electrons from the atoms
B. Energy by proton transition
C. Energy by electron transition
D. Neutron from the atom