Question

2 gm of Oxygen contains number of atoms equal to : [S=32;H=1;N=14;Na=23]


0.5 gm of Hydrogen.

4 gm of Sulphur.

7 gm of Nitrogen.

2.3 gm of Sodium.

pls show Working also​

Answer 1

Given,

Mass of:

==> S = 32 g

==> H = 1 g

==> N = 14 g

==> Na = 23 g

Given mass of Oxygen = 2 g

Molar mass of Oxygen = 16 g

So,

Number of moles = given mass / molar mass

==> number of moles = 2/16

==> number of moles = 0.125 mole

So,

Number of atoms = 6.022 × 10^23 × 0.125

==> 0.75 × 10^23 atoms

Hydrogen, given mass of H = 0.5 g

Molar mass = 1 g

==> no. of moles = 0.5 / 1

==> no. of moles = 0.5 mole

so,

number of atoms = 0.5 × 6.022 × 10^23

==> 3.01 × 10^23 atoms ...(1)

Sulphur, given mass of S = 4 g

molar mass = 32 g

==> no. of moles = 4/32

==> no. of moles = 1/8

==> no. of moles = 0.125 moles

So,

Number of atoms = 0.125 × 6.022 × 10^23

==> 0.75 × 10^23 atoms ...(2)

Nitrogen, given mass of N = 7 g

molar mass = 14 g

==> no. of moles = 7/14

==> no. of moles = 0.5 mole

So,

Number of atoma = 0.5 × 6.022 ×10^23

==> 3.01 × 10^23 atoms ...(3)

Sodium, given mass of Na = 2.3 g

molar mass = 23 g

==> no. of moles = 2.3/23

==> no. of moles = 0.1

now,

Number of atoms = 0.1 × 6.022 × 10^23

==> 0.60 × 10^23 atoms ...(4)

From (1) , (2) , (3) and (4)

==> number of atoms of Oxygen = Number of atoms of Sulphur

So,

The correct answer is Option - 2

4 g of Sulphur