The number of electrons present in 4.2 gram of methane is

Explanation:

One CH4 molecules = 10 electrons ( Carbon 6e + 4Hydrogen 4e)

A mole of any substance witll have = 6.023*10^23 atom/ molecuels,

One mole of any substnce is equal is nothing but its moalr mass

Molar mass of CH4 = 16.04

It mean,

16.04  g of CH4 has = 6.023*10^23 molecules of methane

but

4.2 gram of CH4   = 6.023*10^23 * 4.2 /16.04 = 1.58*10^23 molecuels of CH4

So one molecule has =10 electrons

1.58*10^23 molecuels will have = 1.58*10^23  * 10 = 1.58*10^24

Hope this help you