JAMB Chemistry Past Questions & Answers - Page 183

911.

The solution of a sample in a tube will be identified as a chloride if it gives

A.

a white precipitate on addition of AgNO3 and barium chloride solutions

B.

a white precipiate when acidified with HCI, and then AgNO3 solution added

C.

a white precipitate when acidified with dilute HNO3 and then AgNO3 solution added

D.

a white precipitate when acidified with dilute H2SO4 and then barium nitrate solution added

E.

a pungent smell of chlorine gas when dilute HCI and MnO2 are added

Correct answer is C

No explanation has been provided for this answer.

912.

The reaction 3C(s) + 2Fe2O3(s) = 4Fe(s) + 3CO2(g): \(\Delta\)H =46.0 kJ is

A.

isothermic

B.

adiabatic

C.

isobaric

D.

endothermic

E.

exothermic

Correct answer is D

No explanation has been provided for this answer.

913.

The vapour density of a gas may be defined as

A.

the mass of a unit volume of the gas compared to an equal volume of water vapour

B.

the mass of a unit volume of the gas compared to an equal volume of hydrogen

C.

the mass of a unit volume of the gas compared to an equal volume of oxygen

D.

the mass of a unit volume of the gas minus the vapour pressure of water

E.

two times the relative molecular mass of the gas

Correct answer is B

No explanation has been provided for this answer.

914.

Which of the following statements is true?

A.

an increase in the temperature of a given mass of gas increases the number of gas molecules

B.

an increase in the temperature of the gas does not affect the kinetic energy

C.

an increase in the pressure of the gas is proportional to the increase in volume

D.

a increase in the pressure of a gas is proportional to the decrease in volume at constant temperature

E.

a decrease in the pressure of the gas decreases the number of gas molecules present

Correct answer is D

The basic concept of Boyle's law.

915.

In the manufacture of iron in the blast furnace, iron (lll) oxide is mixed with coke and limestone, and different reactions occur in the process. Which of the following statements is true with respect to these reactions?

A.

the coke is a powerful reducing agent and easily converts the iron oxide to iron

B.

the calcuim carbonate reacts with SiO2 an earthly impurity in the ore, to from calcuim silicate

C.

the coke will react with the iron produced to form steel

D.

all the carbondioxide required in the process comes from the decomposition of the calcium carbonate

E.

the calcium carbonate decomposes to give calcium oxide, which then forms calcium silicate with the earthly impurity

Correct answer is E

No explanation has been provided for this answer.