The surface area of a sphere is 154 cm2.

(a) $179 \frac{2}{3} \mathrm{~cm}^{3}$

Surface area of a sphere $=4 \pi r^{2}$

Therefore,

$4 \pi r^{2}=154$

$\Rightarrow 4 \times \frac{22}{7} \times r^{2}=154$

$\Rightarrow r^{2}=\left(154 \times \frac{7}{88}\right)$

$\Rightarrow r^{2}=\frac{49}{4}$

$\Rightarrow r^{2}=\left(\frac{7}{2}\right)^{2}$

$\Rightarrow r=\frac{7}{2} \mathrm{~cm}$

Volume of the sphere $=\frac{4}{3} \pi r^{3}$

$=\left(\frac{4}{3} \times \frac{22}{7} \times \frac{7}{2} \times \frac{7}{2} \times \frac{7}{2}\right) \mathrm{cm}^{3}$

$=\frac{539}{3} \mathrm{~cm}^{3}$

$=179 \frac{2}{3} \mathrm{~cm}^{3}$