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.

741.

The salt formed from a weak acid and a strong base hydrolyzes in water to form

A.

A saturated solution

B.

an acidic solution

C.

a buffer solution

D.

an alkaline solution

Correct answer is D

This is a solution formed from the hydrolyses of an alkali in water.

742.

Incomplete oxidation of ethanol yields

A.

CH3COOH

B.

CH3COCH3

C.

CH3CH2OCH2CH3

D.

CH3CHO

Correct answer is D

C2H5OH → CH3CHO → CH3COOH
Ethanol.....oxidation Ethanal........Ethanoic Acid
Primary alcohol oxidises to aldehyde and later to carboxylic acid.
Secondary alcohol oxidises to ketones.
Ethanol is an example of primary alcohol and primary alcohol can be oxidised to aldehyde and carboxylic acid. Wherein, incomplete oxidation of primary alcohol yields aldehyde also known as alkanal while complete oxidation of primary alcohol yields carboxylic acid.

743.

A sample of orange juice is found to have a PH of 3.80. What is the concentration of the hydroxide ion in the juice?

A.

1.6 \(\times\) 10-4

B.

6.3 \(\times\) 10-11

C.

6.3 \(\times\) 10-4

D.

1.6 \(\times\) 10-11

Correct answer is B

PH = - Log[ H+ ]

PH + POH =14

POH = 14 - 3.8

POH = 10.2

POH = - Log[ OH- ]

10.2 = - Log[ OH- ]

10-10.2 = [ OH- ]

[ OH- ] = 6.3 x 10-11

744.

When few drops of concentrated trioxonitrate(V) acid is added to an unknown sample and wanned an intense yellow colouration is observed. The likely functional group present in the sample is

A.

NH2RCHCOOH

B.

CHO

C.

CO

D.

CNH2

Correct answer is A

Xanthopreitic test for the presence of protein, when conc nitric acid is added to the drop, an intense yellow colouration is observed.

It contains all the functional group of protein which includes the amino, alkanol and the carboxylic group. Adding few drops of conc HNO3 to a protein, gives an intense yellow colouration.

It is called Xanthopreitic test.

745.

An isomer of C5H12 is

A.

2–ethyl butane

B.

butane

C.

2–methyl butane

D.

2–methyl propane

Correct answer is C

C5H12 has 5 carbons acid 12 hydrogens.

2–methyl butane

No of carbon=5

No of hydrogen=12