Question

Number of molecules of methyl alcohol present in
100 ml, 0.2 M solution of methyl alcohol in water is
(1) 20 NA
(2) 2 × 10"-3 NA
(3) 2NA
(4) 2 x 10"-2 NA
​

Answer 1

GIVEN :-

• Molarity = 0.2M
• Volume = 100ml

TO FIND :-

• Number of molecules of methyl alcohol.

TO KNOW :-

$\\ \bigstar\boxed{\sf \: Molarity = \frac{Moles \: of \: solute}{Volume \: of \: solution(ml)} \times 1000}$

SOLUTION :-

We have ,

• Molarity = 0.2M
• Volume = 100ml

Putting values in formula ,

$\\ \implies \sf \: 0.2 = \frac{moles}{ \cancel{100}} \times 10 \cancel{00 }\\ \\ \implies \sf \: 0.2 = moles \times 10 \\ \\ \implies \boxed{\sf \: moles = 0.02}$

Hence , 0.02 mole of methyl alcohol is present in the solution.

We know ,

$\\ \boxed{ \sf \: 1mol \to N_{A} }$

So,

$\\ \sf \: 0.02 mol \to 0.02 N_{A} \\ \\ \sf \: 0.02mol \to 2 \times {10}^{ - 2} N_{A}$

Option (4)

Answer 2

Answer:

4th option is the answer for the given question