2.4$\times$10²⁴  hydrogen atoms are present in----- grams of methane

Each mole of CH₄ contains….1 gram atom or 1 mole atom or 1 mole of carbon ;

Each mole of CH₄ contains….4 gram atoms (4 N_A) or 4 mole atoms (4 N_A)  of hydrogen ;

$4\times 6\times {10}^{23}(2.4\times {10}^{24}) \mathrm{H}-\mathrm{atoms} \mathrm{are} \mathrm{present} \mathrm{in} 16 \mathrm{g} \mathrm{of} {\mathrm{CH}}_4$