Answer:
0.67 grams of CH4
Explanation:
To convert from molecules to grams, you need to first convert to moles then convert to grams.
Avogadro's Number (6.022 x 10^23) tells us how many molecules are in a mole.
(2.5 x 10^22)/(6.022 x 10^23) = 0.041514 moles of CH4
Then we convert from moles to grams by multiplying moles of CH4 by the molar mass.
0.041514 moles of CH4 x 16.04 g= 0.67 grams of CH4