50% by mass of a 2.2 moles mixture of He and Ar gasses .
Calculate the mole number of He
in the mixture?

Mol He in the mixture = 2

Given

50% by mass

2.2 moles of mixture

Required

The mole number of He

Solution

50% by mass⇒ mass of He : mass of Ar = 1 : 1

Mol He = 2.2 - mol Ar

mass He = mass Ar

mol x MW He = mol x MW Ar

(2.2-mol Ar) x 4 = mol Ar x 40

8.8 - 4 mol Ar = 40 mol Ar

8.8 = 44 mol Ar

mol Ar= 0.2

mol He = 2.2 - 0.2 = 2

c is having 4 valence electrons and is bonded to three hydrogens and one sulphur atom, therefore, the number of bond pair is equal to four. as all the valence electrons are used in forming the bonds so, there is no lone pair left on carbon.

s is having 6 valence electrons and is bonded to one other sulfur atom and one carbon atom, therefore, the number of bond pair is equal to 2. as only two valence electrons are used in forming the bonds so, four electrons are left. therefore, two lone pairs are present on s.