JAMB Chemistry Past Questions & Answers - Page 14

66.

Stainless steel is an alloy made up of

A.

Iron and zinc

B.

Copper and tin

C.

Iron and chromium

D.

Iron and carbon

Correct answer is C

Stainless steel is an alloy composed of iron and chromium, with small amounts of other elements like nickel and molybdenum. The addition of chromium provides stainless steel with excellent corrosion resistance.

67.

A gas occupies a volume of 1.5 liters at a pressure of 2 atmospheres. If the pressure is increased to 4 atmospheres while the temperature remains constant, what will be the new volume of the gas?

A.

6 liters

B.

1.5 liters

C.

0.75 liters

D.

3 liters

Correct answer is C

According to Boyle's law (for constant temperature), the product of initial pressure and initial volume is equal to the product of final pressure and final volume. Therefore, (1.5 liters) × (2 atmospheres) = (new volume) × (4 atmospheres). Solving for the new volume gives us (new volume) = (1.5 liters × 2 atmospheres) / 4 atmospheres = 0.75 liters.

68.

What is Faraday's constant?

A.

6.022 x 10\(^{23}\) mol\(^{-1}\)

B.

3.00 x 10\(^8\) m/s

C.

9.81 m/s\(^2\)

D.

96,485 C/mol

Correct answer is D

Faraday's constant is a proportionality constant that relates the amount of electric charge (in coulombs) required to liberate or deposit one mole of substance during an electrolytic reaction. Its value is approximately 96,485 C/mol.

69.

Which of the following methods can be used to remove temporary hardness from water?

A.

Boiling

B.

Filtration

C.

sedimentation

D.

Chlorination

Correct answer is A

Temporary hardness in water can be removed by boiling. When water is boiled, the calcium and magnesium bicarbonates decompose, forming insoluble calcium carbonate (CaCO3) and magnesium carbonate (MgCO3), which precipitate out of the water.

70.

Which trace gas in the atmosphere plays a significant role in the greenhouse effect?

A.

Oxygen

B.

Argon

C.

Carbon dioxide

D.

Nitrogen

Correct answer is C

Carbon dioxide (CO2) is a trace gas in the atmosphere, but it plays a significant role in the greenhouse effect. It absorbs and traps heat from the Earth's surface, contributing to global warming.