Question

how many atoms are there in 0.25 mole of hydrogen

Answer 1

Number of atoms in 1 mole of hydrogen gas = 2 x 6.022 x 1023

Number of atoms in 0.25 mole of hydrogen gas = 0.25 x 2 x 6.022 x 1023

                                                                             = 3.011 x 1023 atoms.

Answer 2

Given that,

Number of moles of hydrogen, n = 0.25 mole

To find,

How many atoms are there in 0.25 mole of hydrogen

?

Solution,

One mole of hydrogen contains $N_A$ atoms of hydrogen.

To find the number of atoms in 0.25 moles of hydrogen, multiply 0.25 by $6.023\times 10^{23}$. So,

$N=0.25\times 6.022\times 10^{23}\\\\N=1.5\times 10^{23}$

$H_2$ contains 2 hydrogen atoms. So, the number of atoms,

$N=2\times 1.5\times 10^{23}\\\\N=3.01\times 10^{23}$

Hence, there are $3.01\times 10^{23}$ atoms in 0.25 moles of hydrogen.