Given molar mass of methane , M = 16.04 g/mol
(a) mass of metahne , m = 2.750 g
We know that Number of moles , n = mass/molar mass
                                                 Â
= 2.750 g / 16.04 (g/mol)
                                                 Â
= 0.17 moles
(b) We know that 1 mole of any compound contains avagadro number
(6.023x1023) molecules
So 11.5 moles of methane contains 11.5 mol x (
6.023x1023 molescules / 1 mol )
                                                  Â
= 6.93x1024 molecules
