1. Write the dissociation of $A_2B$

Assuming complete ionic breakup on ionisation: $A_2B \rightarrow 2A + B$ So, one formula unit of $A_2B$ gives 3 particles after ionisation.

2. Use degree of ionisation

Given degree of ionisation: $\alpha = 30\% = 0.3$

3. Formula for van't Hoff factor

If one molecule gives $\nu$ particles on dissociation, then $i = 1 + (\nu - 1)\alpha$ Here, $\nu = 3$ So, $i = 1 + (3-1)(0.3)$ $i = 1 + 2(0.3)$ $i = 1 + 0.6 = 1.6$

4. Express in the asked form

The question asks for the value in the form: $\underline{\hspace{2cm}} \times 10^{-1}$ Now, $1.6 = 16 \times 10^{-1}$

So the required integer is: $\boxed{16}$

5. Comparison with stored answer

Stored correct answer = $16$

Our derived answer also = $16$, so they agree.