The valency shell of element A contains 3 electrons while the valency shell of element B contains 6 electrons. If A combines with B, the probable formula of the compound formed will be

Options

A. `AB_2`
B. `A_2B`
C. `A_2B_3`
D. `A_3B_2`

Answer

To determine the probable formula of the compound formed when element A combines with element B, we need to analyze the valency of each element based on the number of electrons in their valency shells.

### Step-by-Step Solution:

1. **Identify the Valency of Each Element:**
- Element A has 3 electrons in its valency shell. This means it can lose 3 electrons to achieve a stable electronic configuration (like that of a noble gas). Therefore, the valency of element A is +3.
- Element B has 6 electrons in its valency shell. This means it needs 2 more electrons to complete its octet (8 electrons in the valency shell). Therefore, the valency of element B is -2.

2. **Determine the Ratio of Combination:**
- To form a neutral compound, the total positive charge must equal the total negative charge.
- Element A (with a valency of +3) and element B (with a valency of -2) can combine in such a way that the charges balance out.
- Let the number of A atoms be x and the number of B atoms be y.
- The equation for charge balance can be written as:
\[ 3x + (-2y) = 0 \]
- Rearranging gives:
\[ 3x = 2y \quad \text{or} \quad \frac{x}{y} = \frac{2}{3} \]

3. **Finding the Smallest Whole Number Ratio:**
- The smallest whole number ratio for x and y that satisfies the equation is x = 2 and y = 3.
- This means 2 atoms of A combine with 3 atoms of B.

4. **Writing the Formula:**
- Based on the ratio determined, the formula of the compound formed will be:
\[ A_2B_3 \]

### Final Answer:
The probable formula of the compound formed when element A combines with element B is \( A_2B_3 \).