The average speed of gas is expressed as, `mu_("av")=sqrt((xRT)/(piM))`, the value of x is

Answer

To find the value of \( x \) in the equation for the average speed of a gas, we start with the given formula:

\[ \mu_{\text{av}} = \sqrt{\frac{xRT}{\pi M}} \]

We also know another expression for the average speed of a gas, which is:

\[ \mu_{\text{av}} = \sqrt{\frac{8RT}{\pi M}} \]

### Step 1: Set the two expressions for average speed equal to each other.

Since both expressions represent the average speed of a gas, we can set them equal to each other:

\[ \sqrt{\frac{xRT}{\pi M}} = \sqrt{\frac{8RT}{\pi M}} \]

### Step 2: Square both sides to eliminate the square root.

Squaring both sides gives us:

\[ \frac{xRT}{\pi M} = \frac{8RT}{\pi M} \]

### Step 3: Cancel out common terms.

Since \( RT \) and \( \pi M \) are present in both sides of the equation, we can cancel them out (assuming they are not zero):

\[ x = 8 \]

### Conclusion

Thus, the value of \( x \) is:

\[ \boxed{8} \]