Element 'X' having electronic configuration `1 s^(2) 2s^(2) 2p^(6), 3s^(2) 3p^(3)` form compound with Ca. The compound is :

Options

A. `Ca_2 X_3`
B. `Ca_2 X`
C. `Ca_3 X_3`
D. `CaX`

Answer

To solve the question, we need to identify the element 'X' based on its electronic configuration and determine the compound it forms with calcium (Ca).

### Step-by-Step Solution:

1. **Identify the Element 'X':**
- The electronic configuration provided is `1s² 2s² 2p⁶ 3s² 3p³`.
- The outermost electrons are in the 3rd shell, which contains 2 electrons in the 3s subshell and 3 electrons in the 3p subshell.
- This corresponds to the element phosphorus (P), which is in group 15 (the nitrogen family) of the periodic table.

2. **Determine the Valency of Phosphorus:**
- Phosphorus has 5 valence electrons (2 from 3s and 3 from 3p).
- To achieve a stable octet, phosphorus needs 3 more electrons. Therefore, it typically forms a -3 oxidation state when it gains 3 electrons.

3. **Identify Calcium:**
- Calcium (Ca) is an alkaline earth metal located in group 2 of the periodic table.
- It has 2 valence electrons and typically loses these 2 electrons to form a +2 oxidation state.

4. **Forming the Compound:**
- When calcium and phosphorus react, calcium will lose 2 electrons to form Ca²⁺ ions, and phosphorus will gain 3 electrons to form P³⁻ ions.
- To balance the charges in the compound, we need 3 calcium ions (Ca²⁺) for every 2 phosphorus ions (P³⁻).
- Therefore, the formula for the compound formed will be Ca₃P₂.

5. **Expressing the Compound in Terms of 'X':**
- Since we identified phosphorus as element 'X', we can express the compound as Ca₃X₂.

### Final Answer:
The compound formed between element 'X' (phosphorus) and calcium is **Ca₃X₂**.