An element 'X' has mass number 35 and number of neutrons 18. Write atomic number and electronic configuration of 'X'. Also write group number, period number and valency of 'X'.

Explanation

To solve the question step by step, we will find the atomic number, electronic configuration, group number, period number, and valency of the element 'X' which has a mass number of 35 and 18 neutrons.

### Step 1: Calculate the Atomic Number
The atomic number (Z) can be calculated using the formula:
\[ \text{Atomic Number} = \text{Mass Number} - \text{Number of Neutrons} \]

Given:
- Mass Number = 35
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