JEE Main · 2021 · 24 Feb 2021 · Shift 1 · Some Basic Concepts of Chemistry

4.5 g of compound A (MW = 90) was used to make 250 mL of its aqueous solution. The molarity of the solution in M is

x \times 1 0^{- 1}

. The value of x is ____. (Rounded off to the nearest integer)

Answer: 2

Solution

To find the molarity, we use the formula:

Molarity (M) = \frac{Number of moles}{Volume in liters}

Step 1: Calculate the number of moles of compound A:

Moles = \frac{Mass}{Molar mass} = \frac{4.5 g}{90 g/mol} = 0.05 mol

Step 2: Convert volume to liters:

Volume = \frac{250 mL}{1000} = 0.250 L

Step 3: Calculate molarity:

M = \frac{0.05}{0.250} = 0.2 mol/L = 2 \times 1 0^{- 1} M

Therefore,

x = 2

Answer: 2

JEE Main · 2021 · 24 Feb 2021 · Shift 1 · Integer answer