The wheel of a motorcycle is of radius 35 cm.

The radius of wheel of a motorcycle = 35 cm = 0.35 m.

So, the distance covered by this wheel in 1 revolution will be equal to perimeter of wheel i.e. $2 \pi r=2 \times \frac{22}{7} \times 0.35=2.2 \mathrm{~m}$.

Since speed is given to be $66 \mathrm{~km} / \mathrm{hr}=66 \times \frac{1000 \mathrm{~m}}{60 \mathrm{~min}}=1100 \mathrm{~m} / \mathrm{min}$.

As we know speed $=\frac{\text { distance }}{\text { time }}$

$\Rightarrow 1100=\frac{\text { number of revolutions } \times \text { perimeter of wheel }}{\text { time }}$

$\Rightarrow 1100=\frac{\text { number of revolutions } \times 2.2}{1}$

$\Rightarrow$ number of revolutions $=\frac{1100}{2.2}=500$ revolutions.