Question

62. Which two elements are in same period as well as
same group of modern periodic table :-
(1) Z = 23, Z = 31
(2) Z = 65, Z = 66
(3) Z = 52, Z = 87
(4) Z = 58, Z = 46
​

Answer 1

Answer:

1 both are in same period (4) but not in same group

2 both are in same period (6)

3 they are not in same period and non in same group

4 they are not in same period and non in same group

Answer 2

Answer:

The two elements of atomic numbers ( Z = $65$ , Z = $66$ ) are present in the same period and in the same group, i.e., in the lanthanoid series.

Therefore, option 2) Z = $65$ , Z = $66$ is the correct option.

Explanation:

In the modern periodic table,

• The elements which lie in the same period and in the same group are present either in the lanthanoid series or in the actinoid series.

Now,

• The lanthanoid series comes under period $6$ and group $3$, i.e., atomic numbers $57-71$.
• The actinoid series comes under period $7$ and group $3$, i.e., atomic numbers $89-103$.

I) Z = $23$ , Z = $31$

• None of the given atomic numbers is present in the lanthanoid series and the actinoid series.

Thus, they do not belong to the same period and the same group.

II)  Z = $65$ , Z = $66$

• Both the atomic numbers lie in the lanthanoid series.

Thus, they belong to the same period $6$ and the same group $3$.

III) Z = $52$, Z = $87$

• None of the given atomic numbers is present in the lanthanoid series and the actinoid series.

Thus, they do not belong to the same period and the same group.

IV) Z = $58$, Z = $46$

• The atomic number $58$ lies in the lanthanoid series, but the atomic number $46$ does not lie in the lanthanoid series.

Thus, they do not belong to the same period and the same group.