In chemistry, .mole. is an essential tool for the chemical calculations. It is a basic S.I. unit adopted by the `14^(th)` general conference on weights and measurements in 1971. A mole contains as many elementary particles as the number of atoms present in 12 g of C. 1 mole of a gas at STP occupies 22.4 litre volume. Molar volume of solids and liquids is not definite. Molar mass of a substance is also called gram atomic mass or gram molar mass. The virtual meaning of mole is plenty, heap or the collection of large numbers. 1 mole of a substance contains `6.023xx10^(23)` elementary particles like atom or molecule. Atomic mass unit (amu) is the unit of atomic mass, e.g., atomic mass of single carbon is 12 amu.
The mass of one molecule of water is approximately

Options

A. 1 g
B. 0.5 g
C. `1.66xx10^(-24)g`
D. `3xx10^(-23)g`

Answer

D

Explanation

1molecule = 18 amu
`=18xx1.66xx10^(-24)g=3xx10^(-23)g`