What is the sum of group number and period number (according to IUPAC system ) of the non-metal which exist in liquid state at room temperature

Explanation

To solve the question, we need to identify the non-metal that exists in a liquid state at room temperature and then determine its group and period numbers according to the IUPAC system.

### Step-by-Step Solution:

1. **Identify the Non-Metal in Liquid State:**
- At room temperature (approximately 25°C), the only non-metal that exists in a liquid state is bromine (Br).

2. **Determine the Group Number:**
- In the periodic table, bromine is located in Group 17 (the halogens).

3. **Determine the Period Number:**
- Bromine is found in Period 4 of the periodic table.

4. **Calculate the Sum:**
- Now, we add the group number and the period number together:
\[ \text{Group Number} + \text{Period Number} = 17 + 4 = 21 \]

5. **Final Answer:**
- The sum of the group number and period number for bromine is 21.