Chlorophyll extracted from the crushed green leaves was dissolved in water to make 2 L solution of Mg of concentration 48 ppm . The number of atoms of Mg in this solution is $\mathrm{x} \times 10^{20}$ atoms. The value of $x$ is ______. (Nearest Integer) (Given : Atomic mass of Mg is $24 \mathrm{~g} \mathrm{~mol}^{-1}$, $\mathrm{N}_{\mathrm{A}}=6.02 \times 10^{23} \mathrm{~mol}^{-1}$ )

JEE Main · 2022 · 26 Jul 2022 · Shift 1 · Some Basic Concepts of Chemistry

Chlorophyll extracted from the crushed green leaves was dissolved in water to make 2 L solution of Mg of concentration 48 ppm . The number of atoms of Mg in this solution is

x \times 1 0^{20}

atoms. The value of

x

is ______. (Nearest Integer)
(Given : Atomic mass of Mg is

24 g mol^{- 1}

N_{A} = 6.02 \times 1 0^{23} mol^{- 1}

)

Answer: 24

Solution

ppm = (mass of Mg / volume of solution in mL) × 10⁶ = 48. For 2 L solution: mass of Mg = (48 × 2000) / 10⁶ = 0.096 g. Moles of Mg = 0.096 / 24 = 4 × 10⁻³ mol. Number of Mg atoms = 4 × 10⁻³ × 6.02 × 10²³ = 24.08 × 10²⁰. Therefore, x = 24 (nearest integer).

JEE Main · 2022 · 26 Jul 2022 · Shift 1 · Integer answer

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