If 64 identical small spheres are made out of a big sphere

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If 64 identical small spheres are made out of a big sphere of diameter 8 cm, what is surface area of each small sphere ?

1. π cm²
2. 2 π cm²
3. 4 π cm²
4. 8 π cm²

Correct Option: C

Volume of small spheres
= Volume of bigger sphere / Number of small spheres = [(4/3)π(4)³] / 64
= [(4/3) x π x 4 x 4 x 4] / 64
= 4/3 π cm³

Let radius of small sphere be r
∴ 4/3πr³ = 4π/3
⇒ r² = 1 cm
Now, surface area of small sphere = 4πr² = 4π cm²