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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.

196.

2H2 + O2 → 2H2O

From the equation above, calculate the volume of unreacted oxygen gas if a mixture of 50cm3 of hydroden and 75cm3 of oxygen are involved

A.

85cm3

B.

50cm3

C.

125cm3

D.

55cm3

Correct answer is B

Since 2 mol H2 reacted with 1 mol of O2

: 50cm3 of hydrogen reacted with 25cm3 of oxygen

Remainder oxygen = Supplied amount - Reacted amount → 75cm3 - 25cm3

= 50cm3

197.

An organic compound contains 69% carbon, 15.3% hydrogen and 30.7% oxygen. Calculate the the empirical formula [C=12, H = 1, O = 16]

A.

C4H12O

B.

C3H9O

C.

C4H9O

D.

C3H8O

Correct answer is D

6912   H  15.31     O  30.716

C = 5.75,  H = 15.3,  O = 1.92

C 5.751,92    H  15.31.92     O  1.921.92

C3H8O

198.

Crude petroleum is converted to useful products by the process of?

A.

fractional crystallization

B.

fractional distillation

C.

filtration

D.

chromatography

Correct answer is B

A process called fractional distillation is used in oil refineries to separate (as well as join or split) the various lengths of hydrocarbon chains to create different petroleum products from the different distillates.

199.

An organic compound which decolorizes bromine water is likely to be?

A.

C3H8

B.

C2H6

C.

C4H10

D.

C2H4

Correct answer is D

If you shake an alkene with bromine water (or bubble a gaseous alkene through bromine water), the solution becomes colourless.

Alkenes decolourise bromine water.

200.

In order to electroplate spoon with silver, the arrangement of the electrolytic cell is?

A.

the anode is a silver rod and the cathode is the spoon

B.

the anode is the spoon and the cathode is a silver rod

C.

the electrolyte is silver trioxonitrate(v)( solution and the cathode is a silver rod.

D.

the electrolyte is silver trioxonitrate(v) solution and the anode is the spoon

Correct answer is A

The steel spoon to be coated with silver is the cathode of the electrolytic cell and the anode of the electrolytic cell is made of a silver metal