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?
Answer & explanation
Correct answer: option 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