Question

Can anyone explain Qno 1 and 4 with the answers marked?

Answer 1

1. No. Of mole in 22.4L of gas is 1.

So to find the volume of gas at STP, we can multiply no. Of moles to 22.4 L and vice versa.

So correct answer is A.

4. I.5 moles of CO2 and H2O have not same mass because
1 Mol of CO2 = 44g
Hence 5 moles of CO2 = 44*5
=220 g while
1 Mol of H2O = 18g
Hence 5 moles of H2O = 18*5
=90g.

II. Gram molecular mass of NH3= 17 g
Hence 17 g = N molecules
= 100g = N * 100/17 g.
While gram molecular mass of N2=28g
Hence 28g = N molecules
= 100g = N * 100/28

This imply that NH3 have more molecules than N2. Also atoms so it is correct.

III. Solid Sulphur gram molecular mass = S8 = 256 g
This imply that 256 g = N molecules

This implies that 16g have N*16/256
=N/16
=6.023*10^23/16
=3.76*10^22 molecules.
Means B. Is correct.

Hope it's helpful to u.