Explanation:

Let’s break it down:

- When you melt a sphere and recast it, the total volume stays the same.

- Volume of a sphere = (4/3)pr³.

- So, original big sphere’s volume = (4/3)p×7³ = (4/3)p×343 = 1436.76 cm³ (rounded).

- Small sphere’s volume = (4/3)p×2³ = (4/3)p×8 = 33.51 cm³ (rounded).

- Number of small spheres = Total Volume ÷ Each Small Sphere’s Volume = 1436.76 ÷ 33.51 ˜ 42.9.

- Since you can't have a fraction of a sphere, you get 42 whole small spheres.

Let’s check those options:

- 40: too low

- 41: still too low

- 42: Correct

- 43: a bit too high