0.1 percent of 1.728 × 10⁶ spherical droplets of water, each of diameter 2 mm, coalesce to form a spherical bubble. What is the diameter (in cm) of the bubble?

2.4

We know that,

Volume of sphere = \(\frac{4}{3}\) × π × r³

Total number of small droplets =  0.1% of 1.728 × 10⁶ = 1728

Let the radius of bubble = R

1728 × \(\frac{4}{3}\) × π × (1)³ = \(\frac{4}{3}\) × π × R³

= R³ = 1728

= R = 12 mm or 1.2 cm

Then diameter = 2 × 1.2 = 2.4 cm