JAMB Chemistry Past Questions & Answers - Page 174

866.

Hydrogenation may be effected by

A.

the removal of hydrogen from an alkane in the presence of a catalyst

B.

the addition of hydrogen to an alkane in the presence of a catalyst

C.

the addition of hydrogen to an alkyne

D.

the removal of hydrogen from an alkyne

E.

the addition of hydrogen to an ethyl alcohol

Correct answer is C

No explanation has been provided for this answer.

867.

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.

868.

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.

869.

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.

870.

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.