NECO Chemistry Past Questions & Answers - Page 31

151.

How much sodium hydroxide is required to make 250 cm3 of 0.1 molar solution? Na=23; 0=16; H=1]

A.

10.0 g

B.

4.0g

C.

2.0 g

D.

1.0g

E.

0.1 g

Correct answer is D

no of moles of Na = molar concentration X   volume

                             = 0.1 x \(\frac{250}{1000}\) = 0.025

no of moles =  \(\frac{m}{M}\) 

mass = no of mles x molar mass = 0.025 x 40 = 1.0g ( molar mass of NaOH = 40g/mol)

152.

What is the ratio of the rate of diffusion of carbon(IV) oxide to that of propane, under the same conditions? [H = 1; C= 12; 0= 161

A.

1:01

B.

1:01

C.

2:01

D.

2:03

E.

3:01

Correct answer is A

No explanation has been provided for this answer.

153.

The maximum number of electrons that can occupy the shell having a principal quantum number of 3 is

A.

3

B.

9

C.

10

D.

18

E.

32

Correct answer is D

No explanation has been provided for this answer.

154.

On exposure to hydrogen sulphide, moist lead (II) ethanoate paper turns

A.

black

B.

blue

C.

green

D.

white

E.

yellow

Correct answer is A

No explanation has been provided for this answer.

155.

Which compound is a product of the hydrolysis of the of CH3COOC3H7 with aqueous sodium hydroxide?

A.

CH3COOH

B.

CH3COONaCCH3OH

C.

CH3OH

D.

C2H5OH

E.

C3H7COONa

Correct answer is A

No explanation has been provided for this answer.