(solved)Question 1.28 of NCERT Class XI Chemistry Chapter 1 | Which one of the following will have the largest number of atoms? (i) 1 g Au (s) (ii) 1 g Na (s) (iii) 1 g Li (s) (iv) 1 g of Cl2(g)

Parveen, May 04, 2021

Which one of the following will have the largest number of atoms? (i) 1 g Au (s) (ii) 1 g Na (s) (iii) 1 g Li (s) (iv) 1 g of Cl2(g)

Please watch this youtube video for a quick explanation of the solution:

$\displaystyle \text{no. of moles } = \frac{\text{w (mass)}}{\text{M (molar mass)}}$

$\displaystyle \therefore \text{no. of atoms } = \frac{\text{w}}{\text{M}} \times 6 \times 10^{23}$

but all masses are given same w = 1 gram.

$\displaystyle \therefore \text{atoms} \propto \frac{1}{M}$

$\displaystyle \therefore$ the one with lowest molar mass will have the most number of atoms

Molar masses are Au = 197, Na = 23, Li = 7, Cl2 = 35.5 x 2 = 71 (all in (g/mol) )

Hence lithium, Li, is the answer!

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