Sample paper 2
Question 1
Calculate the molarity (M), when 580g of NaClis added to 2L of water.
a)
5 M
b)
3 M
c)
2.5 M
d)
80 M
e)
10 M
Correct Answer:
a) 5 M
Explanation:
Molarity (M) = (moles of solute/litres of solution)
Molecular weight of NaCl = 23+35= 58 g/mol
Moles of NaCl = 580/58 = 10 mol
Therefore, Molarity (M) = 10 mol/2 L= 5 M
Question 2
Which of the following gas is the most easily liquefied?
Gas
O
2
N
2
NH
3
CH
4
Van der Waals constant (a) 1.3 1.39 4.17 2.21
a)
O
2
b)
N
2
c)
NH
3
d)
CH
4
e)
Can't be predicted using this value
Correct Answer:
c) NH
3
Explanation:
A gas with the greater ‘a' value will liquefy easily. Here NH3 has greater ‘a' value than the other
gases. Therefore, it will liquefy easily.
Question 3
The coordination number of the Na+ in Rock salt is
a)
4
b)
3
c)
6
d)
8