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.

421.

Chromatography is used to separate components of mixture which differ in their rates of ?

A.

diffusion

B.

migration

C.

reaction

D.

sedimentation

Correct answer is B

Chromatography is a method of separating mixtures by using a moving solvent on filter paper. The rate at which each solute moves up the paper depends on how strongly it is absorbed by the paper, and how soluble it is in the solvent.

422.

A few drop of conc HCL are added to about 10cm\(^3\) of a solution of PH 3.4. The PH of the resulting mixture is?

A.

less than 3.4

B.

greater than 3.4

C.

unaltered

D.

the same as that of the pure water

Correct answer is A

The addition of conc HCL makes the solution more acidic and the solution falls below the original value

423.

The shape of ammonia molecule is?

A.

Trigonal planar

B.

Octahedral

C.

Square planar

D.

Tetrahedral

Correct answer is A

The ammonia molecule has a trigonal pyramidal shape with the three hydrogen atoms and an unshared pair of electrons attached to the nitrogen atom.

424.

Which of the following gases will rekindle a brightly splint?

A.

NO\(_2\)

B.

NO

C.

N\(_2\)O

D.

CL\(_2\)

Correct answer is C

Nitrogen(I)Oxide rekindles a brightly glowing splinter but extinguishes a feebly glowing one which is not hot enough to decompose the gas to liberate oxygen

425.

The volume occupied by 1.58g of a gas at S.T.P is 500cm\(^3\). What is the relative molecular mass of the gas?  [ G.M.V at S.T.P = 22.4dm\(^{3}\) ]

A.

28

B.

32

C.

44

D.

71

Correct answer is D

500cm\(^3\) of the gas weighed 1.58

: 22400cm\(^3\) of the gas weight

 

[22400 X 1.58g] ÷ [ 500 ]

= 71