To leave the expression $\frac{4 \sqrt{3}}{\sqrt{2}}$ in surd form, we can simplify it by rationalizing the denominator.

1. Multiply both the numerator and denominator by $\sqrt{2}$ to get rid of the surd in the denominator: $\frac{4 \sqrt{3}}{\sqrt{2}} \times \frac{\sqrt{2}}{\sqrt{2}} = \frac{4 \sqrt{3} \times \sqrt{2}}{\sqrt{2} \times \sqrt{2}} = \frac{4 \sqrt{6}}{2}$

2. Now, simplify the fraction: $\frac{4 \sqrt{6}}{2} = 2 \sqrt{6}$

Thus, $\frac{4 \sqrt{3}}{\sqrt{2}}$ in surd form is $2 \sqrt{6}$.

Would you like more details or have any questions?

Here are five related questions for practice:

1. Simplify $\frac{5 \sqrt{2}}{\sqrt{3}}$.
2. Simplify $\frac{3 \sqrt{5}}{\sqrt{7}}$.
3. What is $\frac{\sqrt{12}}{\sqrt{2}}$ in surd form?
4. Simplify $\frac{6 \sqrt{8}}{\sqrt{4}}$.
5. Rationalize the denominator of $\frac{\sqrt{7}}{\sqrt{5}}$.

Tip: When simplifying expressions with surds, rationalizing the denominator is a helpful technique to eliminate square roots from the denominator.