CIE Chemistry Paper-1: Specimen Questions 23 - 24 of 99

Question number: 23

MCQ▾

Question

CO2 gas reacts with aqueous sodium hydroxide. Which type of reaction occurs?

Choices

Choice (4) Response
a.

neutralisation

b.

oxidation

c.

decomposition

d.

fermentation

Answer

a.

Explanation

The chemical equation depicting the above reaction is:

CO2 (g) + 2NaOH (aq) → Na2CO3 (aq) + H2O (l)

Neutralization is a type of chemical reaction in which a strong acid and strong base react with each other to form water and salt. Co2 is considered to be a strong acid in gaseous form and NaoH is a strong base. It can be seen that when both reacts water is produced along with a salt Na2CO3 i. e. sodium carbonate.

Question number: 24

MCQ▾

Question

Which two elements react together to form an ionic compound?

Various elements with electronic structure

Element R, T, X and Z with electronic structure

element

electronic structure

R

2, 4

T

2, 8

X

2, 8, 1

Z

2, 8, 7

Choices

Choice (4) Response
a.

X and Z

b.

R and T

c.

T and X

d.

Z and R

Answer

a.

Explanation

From the above table it is clear X (2, 8, 1 = Sodium) and belongs to group 1 of periodic table. Whereas Z (2, 8, 7 = Chlorine) belong to Group 17, the halogen group. All the halogens exist as diatomic molecules. They have high ionization energies and form the most electronegative group of elements. Their electron configuration, ns2np5, allows them to easily react with Group 1 and 2 metals; each halogen tends to pick up one electron, and the Group 1 and Group 2 elements each tend to lose one or two electrons.

Share