Chemistry questions and answers

Chemistry Questions and Answers

Learn more about the properties, composition, and structure of substances (elements and compounds) with these Chemistry questions and answers. This Test can be used by students preparing for Chemistry in JAMB, WAEC, NECO or Post UTME.

2,291.

The equilibrium reaction between copper (l) chloride and chlorine at 25oC and 1 atmosphere is represented by the equation:
2CuCl +Cl2 ⇌ 2 CuCl2 ∆H = - 166 KJ. Which of the following statements is TRUE for the reaction, pressure remaining constant?

A.

more CuCl is formed at 40oC

B.

more CuCl2 is formed at 10oC

C.

Less CuCl2 is formed at 10oC

D.

there is no change in the amount of CuCl2 formed at 40oC and10oC

E.

more CuCl is consumed at 40oC

Correct answer is B

No explanation has been provided for this answer.

2,292.

When sodium dioxonitrate (lll) (NaNO2) dissolves in water, ∆H is positive. The process of dissolution is

A.

exothermic

B.

endothermic

C.

isothermal

D.

isomeric

E.

hygroscopic

Correct answer is B

No explanation has been provided for this answer.

2,293.

Which of the following statements is FALSE?

A.

Copper (ll) ion can be reduced to copper (l) ion by hydrochloric acid and zinc

B.

Sodium metal dissolves in water giving oxygen

C.

Nitrogen is insoluble in water

D.

Carbondioxide is soluble in water

E.

lead has a higher atomic weight than copper

Correct answer is B

No explanation has been provided for this answer.

2,294.

Liquid X, reacts with sodium trioxocarbonate (IV) (Na2CO3) to give a gas which turns calcium chloride solution milky X is

A.

Na2SO4(aq)

B.

Kl (aq)

C.

an alkali

D.

an acid

E.

a hydrocarbon

Correct answer is D

No explanation has been provided for this answer.

2,295.

A jet plane carrying 3,000 kg of ethane burns off all the gas forming water and carbondioxide. if all the carbondioxide is expelled and all the water formed is condensed and kept on board the plane, then the gain in weight is

A.

1,800 kg

B.

900 kg

C.

600 kg

D.

2,400 kg

E.

1,200 kg

Correct answer is D

2\(C_2H_6 + 7O_2 →4CO_2 + 6H_2O\)

addition of oxygen causes weight gain, expelled \(CO_2\) results in weight loss

for oxygen added;

2moles \(C_2H_6\) = 7moles \(O_2\)

2(30)g  \(C_2H_6\) = 7(2)(16)g \(O_2\)

3000kg  \(C_2H_6\) = X kg \(O_2\)

cross multiplying X = 11200kg

for \(CO_2\) expelled;

2moles  \(C_2H_6\) = 4moles \(CO_2\)

2(30)g  \(C_2H_6\) = 4(44)g  \(CO_2\)

3000kg \(C_2H_6\) = Y kg  \(CO_2\)

cross multiplying Y = 8800kg

since X > Y, the plane has a net weight gain.

Net weight gain = X - Y = 11200-8800 = 2400kg.