JAMB Chemistry Past Questions & Answers - Page 263

1,311.

A sample of a substance containing only C and H burns in excess O2 to yield 4.4g of CO2
and 2.7 g of H2O. The empirical formula of a substance is?

(C = 12, O = 16, H = 1)

A.

CH3

B.

CH2

C.

CH4

D.

C2H24

Correct answer is A

CxHy + (x + y/4)O2 = XCO2 + (y/2)H2O
4.4 2.7
according to the equation 44x = 9y
Carbon Hydrogen
mole given ratio = (44)/(44), (2.7)/(9) = 0.1,0.3
Empirical formula = (0.1)/(0.1), (0.3)/(o.1) = 1,3 ; CH3

1,312.

Sodium hydroxide is prepared commercially from sodium chloride solution by?

A.

electrolysis using mercury as cathode

B.

hydrolysis in steam using a catalyst

C.

electrolysis using iron as anode

D.

treating sodium chloride with ammonia and carbon (IV) oxide

Correct answer is A

No explanation has been provided for this answer.

1,313.

Which of the additives could improve the quality of steel?

A.

Silicon

B.

Sulphur and phosphorus

C.

Carbon

D.

Chromium and nickel

Correct answer is D

No explanation has been provided for this answer.

1,314.

The removal of rust from iron by treatment with tetraoxosulphate (IV) acid is based on the?

A.

hydrolysis of the iron

B.

reaction of acid with base

C.

oxidationof the rust

D.

dehydration of the iron

Correct answer is D

No explanation has been provided for this answer.

1,315.

2X(aq) + MnO2(s) + 4H+(aq) → X2(g) + Mn2+(aq) + 2H2O.
The reaction above can be used for the laboratory preparation of all halogens except fluorine because it is?

A.

a poisionous gas

B.

an oxidizing agent

C.

electronegative in nature

D.

highly reactive

Correct answer is D

No explanation has been provided for this answer.