Choose from the following :

$6C, 8O, 10Ne, 11Na, 14Si$

(i) Elements that should be in the same period.

(ii) Elements that should be in the same group.

State reason for your selection in each case.

(i) Elements in the same period:

• Set 1: $_{6}\text{C}$, $_{8}\text{O}$, and $_{10}\text{Ne}$ belong to the same period (Period 2).
• Reason: Their electronic configurations are $_{6}\text{C} = 2, 4$, $_{8}\text{O} = 2, 6$, and $_{10}\text{Ne} = 2, 8$. All three elements have electrons distributed in exactly two shells ($K$ and $L$). Since the number of occupied shells determines the period number, they belong to the same period.
• Set 2: $_{11}\text{Na}$ and $_{14}\text{Si}$ belong to the same period (Period 3).
• Reason: Their electronic configurations are $_{11}\text{Na} = 2, 8, 1$ and $_{14}\text{Si} = 2, 8, 4$. Both elements have electrons distributed in three shells ($K$, $L$, and $M$).

(ii) Elements in the same group:

• Elements: $_{6}\text{C}$ and $_{14}\text{Si}$ belong to the same group (Group 14).
• Reason: Their electronic configurations are $_{6}\text{C} = 2, 4$ and $_{14}\text{Si} = 2, 8, 4$. Both elements have the same number of valence electrons (4 electrons in their outermost shell). Since elements with the same number of valence electrons are placed in the same group, they belong to the same group.