How To Calculate The Number Of Moles For 21.0g Of CH4?

Ch4 is the molecular formula for methane. Methane is an organic compound. The molar mass of methane is;

Molar mass of methane = mass of carbon + 4*mass of hydrogen

Molar mass of methane =12 + 4*1 = 16 grams per mole

The mole of substance is equal to the ratio of mass given to molar mass. It can also be calculated by dividing number of atoms present in the sample by Avogadro's number.

Moles = mass of sample/ molar mass

Moles = 21 grams/ 16 grams per mole

Moles = 1.3125

There are 1.3125 moles are present in 21 grams of methane.

Well you take the hydrogen and multiply it it by 4 as it says Ch4
the molar mass of
carbon: 12
hydrogen: 1 * 4 = 4
your formula is n = m/M
n = moles
m = mass of sample
M = Molar mass
answer
n= 21/16
n = 1.3125