Question

8. Analyse the statements given below and correct the
2. As distance from nucleus increases, energy of sheils decreases.
b. Electron filling in shells occurs in the increasing order of energy.
C. As distance increases attraction between the nucleus and electron decreases.
d. s and p subshells are common in all shells.
Section C (Each question carries 3 scores)
9.1 mol of any gas at STP has a volume of 22.4L
a. How many mcies are present in 112 L of So, gas at STP
b. How many molecules are present in this much amount of SO,
c. Calculate the mass of 112 L of NH3 gas at STP (molecular mass of NH,= 17)
10. An element. A has 1 electron in the s' subshell of its 3d shell
a. Write the complete subshell electronic configuration of A
b. Find the atomic number of A.
c. Write the chemical formula of the compound formed when A combines with th
of valency 2
​

Answer 1

Answer:

ANSWER

(i) The first group elements have a common valency of 1 and the valency of oxygen is 2 and to satisfy the combining capacity of oxygen, 2 elements of first group are required. Thus the oxide of the first group elements have the common formula of M

2

O.

Ex- Na

2

O,K

2

O,etc.

(ii) The valency of group 13 elements is 1 and the valency of oxygen is 2 and to satisfy the combining capacity of group 13 elements, 3 of halogens are required. Thus the molecular formula will be of form MX

3

.

Ex- AlCl

3

,BF

3

,etc.

(iii) The valency of group 2 elements is 2 and that of group 17 is 1. Thus two elements of group 17 are required to combine with group 2 element.

Ex- MCl

2

,CaCl

2

,etc.