10 In three moles of ethane (C2H6), calculate the following :

(i) Number of moles of carbon atoms.

(ii) Number of moles of hydrogen atoms.

(iii) Number of molecules of ethane.

i) 1 mole of C₂H₆ contains 2 moles of carbon atoms.

Number of moles of carbon atoms in 3 moles of C₂H₆

= 2 × 3 = 6

(ii) 1 mole of C₂H₆ contains 6 moles of hydrogen atoms.

Number of moles of carbon atoms in 3 moles of C₂H₆

= 3 × 6 = 18

(iii) 1 mole of C₂H₆ contains 6.023 × 10²³ molecules of ethane.

Number of molecules in 3 moles of C₂H₆

= 3 × 6.023 × 10²³ = 18.069 × 10²³

1)c2h6 contain 2 carbon atom so in three moles of ethane it will contain 3*2=6 

2)c2h6 contain 6 carbon aton so in three moles of ethane it will contain 6*3=18

3)1 mole contain 6.022*10²³ so 3 mole will contain 6.022*10²³*3=18.069*10²³

Tough question !