Volume of a sphere

Q. If a sphere of radius $9cm$ is cut into 27 smaller spheres then, the radius of each smaller sphere is .

1. $3cm$
2. $6cm$
3. $9cm$
4. $12cm$

Q.

If a metallic hemisphere is recast into a sphere, then ratios of old radius to new radius are __________.

Q. If a sphere and a cube have the same volume then the ratio of the surface of the sphere to that of the cube is

1. $\sqrt{6}:\sqrt{\pi }$
2. $\sqrt[3]{33\pi }:\sqrt[3]{33}$
3. $\sqrt[3]{3\pi }:\sqrt[3]{36}$
4. none of these