KVPY2019ChemistrySome Basic Concepts of Chemistry
The number of moles of water present in a spherical water droplet of radius 1 . 0   cm is, [Given : Density of water in the droplet = 10   g   cm - 3 ]
Options
- Aπ 18
- B2 π 27
- C24 π
- D2 π 9
Correct answer
B. 2 π 27
Step-by-step solution
Number of moles, n = mass ( m )  molar mass  ( M ) Given, radius = 1 . 0   cm ∴ volume = 4 π 3   cm 3 Given, density = 1 . 0   g   cm - 3 , ∴ Mass = volume × density = 4 π 3   g (Atomic weight of water = 18 ) ∴    n = 4 π 3 × 18 = 2 π 27