Four elements P, Q, R and S have atomic numbers 12, 13, 14 and 15 respectively. Answer the following questions giving reasons:
(i) What is the valency of Q ?
(ii) Classify these elements as metals and non-metals.
(iii) Which of these elements will form the most basic oxide?

Explanation

To solve the given question, we will analyze the elements P, Q, R, and S based on their atomic numbers and electronic configurations.

### Step-by-Step Solution:

1. **Determine the Electronic Configurations:**
- For element P (Atomic number 12):
- Electronic configuration: \(1s^2 \, 2s^2 \, 2p^6 \, 3s^2\)
- For element Q (Atomic number 13):
...