Chemistry Class 11 NCERT Solutions: Chapter 1 Some Basic Concepts of Chemistry Part 11

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Q: 33. Calculate the number of atoms in each of the following

This structure is number of atoms

Structure of Atoms

This structure is number of atoms

(iii)

Answer:

(i)

(ii)

Or,

(iii)

Q: 34. A welding fuel gas contains carbon and hydrogen only. Burning a small sample of it in oxygen gives carbon dioxide, of water and no other products. A volume of (measured at STP) of this welding gas is found to weigh Calculate

A number of wekling processes use a flame produced by burning a mixture of fuel gas and oxygen

Structure Welding Fuel Gas

A number of wekling processes use a flame produced by burning a mixture of fuel gas and oxygen

(i) Empirical formula

(ii) Molar mass of the gas

(iii) Molecular formula

Answer:

(i)

of water contains 2 g of hydrogen.

Since carbon and hydrogen are the only constituents of the compound, the total mass of the compound is:

Percent of H in the compound

Moles of carbon in the compound

Moles of hydrogen in the compound

= 1: 1

Hence, the empirical formula of the gas is CH.

(ii) Given

Weight of of gas

Hence, the molar mass of the gas is

(iii) Empirical formula mass of