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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.

516.

Fats and oils can be obtained from any of the following sources except

A.

paraffin oil

B.

animals

C.

groundnuts

D.

palm kernel

Correct answer is A

Paraffin oil is gotten from petroleum distillation and can't be a source of fats and oil.

517.

Which of the following pairs of gases are pollutants from car exhaust?

A.

Nitrogen(II) oxide and Carbon(IV) oxide

B.

Carbon(IV) oxide and Nitrogen

C.

Carbon(II) oxide and Sulphur(IV) oxide

D.

Carbon(II) oxide and oxygen

Correct answer is C

No explanation has been provided for this answer.

518.

The name of the compound C4H9COOC3H7 is

A.

propyl pentanoate

B.

pentyl propanoate

C.

butyl propanoate

D.

propyl butanoate

Correct answer is A

The alkyl group is attached to the parent chain being a carboxylic acid. The name of the compound is gotten by writing the name of the attached alkyl group first and then the parent carboxylic acid is written but you change the -oic acid to -oate. 

The alkyl group in this case is C3H7

The parent carboxylic acid is C4H9COOH which is pentanoic acid. 

Hence, the name is propyl pentanoate.

519.

Classification of alkanols is based on the 

A.

number of carbon atoms present in the compound

B.

molecular mass of the compound

C.

molecular formula of the compound

D.

number of alkyl groups bonded to the carbon having the hydroxyl group

Correct answer is D

Alkanols can be classified as primary, secondary or tertiary, according to the number of alkyl groups attached to the carbon which bears the -OH group. 

520.

Calculate the mass of copper deposited if a current of 0.45A flows through CuSO4 solution for 1hour 15mins.   [Cu=64.0, S= 32.0, O =16.0, 1F= 96500C]

A.

6.40g

B.

0.67g

C.

0.64g

D.

0.45g

Correct answer is B

Cu2++2eCu(s)

2×96500C=193000Cdeposits64gofCu

MIt

Q=It=0.45A×1hr15mins

= 0.45×75×60 [converting the time to seconds]

Quantity of electricity passed = 2025C

193000C64gCu

1C64193000

2025C64193000×2025

=0.6715g