Question

How many moles are present in 3.6 gram of water?
A. 0.7
B. 0.015
C. 0.05
D. 0.2

Answer 1

Hint: A mole is the term that is used to denote a quantity of Avogadro number of particles. It is the number of atoms that are$6.022\times {{10}^{23}}$, these particles constitute one mole of any substance. The atomic mass of any substance is equal to these numbers of particles that are considered as 1 mole.
Formula used:
Number of moles = $\dfrac{given\,mass}{molar\,mass}$

Complete answer:
A mole is the unit used to measure a group of $6.022\times {{10}^{23}}$particles. 1 mole of any substance is equal to the atomic or molecular mass of that compound that is equal to these numbers of atoms.
We have been given water that has a chemical formula${{H}_{2}}O$ with an amount of 3.6 g. We have to find the number of moles in this amount.
As we know, the molar mass of water that is 18 g/mol will have$6.022\times {{10}^{23}}$ atoms that is equal to 1 mole, therefore, the number of moles in 3.6 g of water will be determined by
Number of moles = $\dfrac{given\,mass}{molar\,mass}$
Number of moles = $\dfrac{3.6\,g}{18\,g/mol}$
Number of moles of water = 0.2
Hence, the number of moles present in 3.6 gram of water are 0.2 moles. So, option D is correct.

Note:
The molar mass of any compound is calculated by adding the atomic mass of the elements present in their respective quantities. Here we have water that is${{H}_{2}}O$, which means the molar mass of water will be the mass of [2(H) + (O)] = [2 + 16] = 18 g/mol. The unit of atomic mass is gram per mole, as this is the mass of$6.022\times {{10}^{23}}$atoms that make up 1 mole.