How many molecules are in a 6.82 gram sample of Hydrogen Sulfide (H2S) Please show and justify each step

1.204×10^(23)

Explanation:

Molecular weight of H2S,  M = 1*2+32 = 34

weight of sample, m = 6.82 gram

now number of moles, n= m/M

n= 6.82/34 = 0.200 moles

1 mole has 6.023×10^(23) molecules of H2S.

therefore 0.2 moles of H2S will have  0.2×6.023×10^(23) = 1.204×10^(23) number of H2S molecules.

the density(ratio between mass and volume as m/v) decreases from top to bottom in periodic table group as the size increases and nuclear charge decreases. but in periods density increases from left to right as atom size decreases and nuclear charge increases.