given mass of methane[CH₄]=1.6 g

no.of moles of methane=(1.6/16)    [since no.of moles=given mass/molar mass]

                                  =0.1

since one carbon atom[E.C.=2,4] has 6 electrons,and four hydrogen atoms[E.C.=1] have four electrons,

therefore

   no.of electrons in one mole of methane=6+4

                                                           =10

total no.of electrons in given mass=10*0.1*6.023*10²³

                                                  =6.023*10²³ electrons