Question

If 3.01 x 1020 molecules are removed from
98 mg of H,SOą, then the number of moles of
H,SO, left are :-
(1) 0.1 x 10-3 (2) 0.5 x 10-3
(3) 166 x 10-3
(3) 1.66 x 10-3 (4) 9.95 x 10-2​

Answer 1

Answer:

2) 0.5 x 10^(-3)

Explanation:

The number of molecules in 98 mg of H₂SO₄ will be

n = Given mass x Avogadro's constant/Molar Mass

n = 98 x 10⁻³ x 6.02 x 10²³ / 98 molecules

n = 6.02 x 10²⁰ molecules

Now, number of molecules removed = 3.01 x 10²⁰

Therefore, number of molecules left = (6.02 - 3.01) x 10²⁰ molecules

= 3.01 x 10²⁰ molecules

Thus, number of moles of H₂SO₄ left are

N = No. of entities/ Avogadro's constant = 3.01 x 10²⁰ / 6.02 x 10²³

= 0.5 x 10⁻³