Question

Find how many moles of atoms are there in:
i) 2 g of nitrogen. ii) 23 g of sodium iii) 40 g of calcium.
iv) 1.4 g of lithium v) 32 g of sulphur

TNSCERT Class 10 Chemistry Ch 10 Atoms and Molecules

Answer 1

i)
=> 1 mole of nitrogen weighs 14 grams(it's atomic mass)
=>(?) moles of nitrogen weigh 2 grams
{by cross multiplication}
=> 2 x 1/ 14
=>0.14 moles.....Ans
ii)
=>1 mole of Sodium weighs 23 grams (it's atomic mass)
=> 1 mole.....Ans
iii)
=>1 mole of calcium weighs 40 grams(it's atomic mass)
=> 1 mole.....Ans
iv)
=>1 mole of lithium weighs 7 grams
=> (?) moles of lithium wighs 1.4 grams
{by cross multiplication}
=>1.4 x 1/ 7
=> 0.2 moles.....Ans
v)
=>1 mole of sulphur weighs 32 grams( it's atomic mass)
=> 1 mole.....Ans