Sphere

Q.

When we rotate a semi-circle along the axis parallel to its plane, what shape do we obtain?

1. Sphere

2. Circle

3. Cylinder

4. Hemisphere

Q. The ratio of the volume and surface area of a sphere of unit radius without considering units is

1. 4 : 3
2. 3 : 4
3. 1 : 3
4. 3 : 1

Q.

The volume of a sphere is $3000\mathrm{\pi }{\mathrm{m}}^3$. What is the surface area of the sphere to the nearest square meter?

Q. If the diameter of a sphere is decreased by $25\%$, then its curved surface area decreases by

1. $44.25\%$
2. $43.50\%$
3. $43.75\%$
4. $75.43\%$