Question

Question #ffeee

Answer 1

Let's denote atomic masses by `"M"_"atom letter"`, molecular masses by `"M"_"molecular formula"`, and let their units be `"g/mol"`.

`"M"_"C" = 12.011`

`"M"_"H" = 1.0079`

`"M"_("CH"_4) = "M"_"C" + 4*"M"_"H"`

`= 12.011 + 4*1.0079 = 16.0426`

But realize that

`"% mass of atom in molecule" = "mass of atom"/"mass of molecule" xx 100%`

Therefore:

`("M"_"C")/("M"_("CH"_4)) = 12.011/16.0426 xx 100% = color(blue)(74.87%)`

`74.87% ~~ 75%`

So yes, it's true.