Question:
The electronic configuration of an element M is 2, 8, 2. In modern periodic table, the element M is placed in
A4th group
B2nd group
C14th group
D18th group
Answer:
B. 2nd group
Explanation:
- The number of shells equals the period number of that element.
- The number of valence electrons indicates the group of that element.
Example:
- Electronic Configuration of Oxygen – 2, 6
- It has 2 shells and 6 valence electrons. So it belongs to 2nd period and 6th group.
Note:
- In the question given that, the electronic configuration is 2,8,2.
- It has 3 shells and 2 valence electrons. So it belongs to 3rd period and 2nd group.
- In modern periodic table, the element M is placed in 3rd period and 2nd group.