JEE Main 2022 — Chemistry Physical Chemistry

2022integereasy

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

Official previous-year question

Held on 26 Jul 2022 · Verified 6 Jul 2026.

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Solution

Chlorophyll is the green pigment in plants, algae, and cyanobacteria that is essential for photosynthesis. Its central structure is an aromatic porphyrin ring system with a sequestered magnesium atom.

$\mathrm{ppm}=\frac{{W}_{{M}_{g}}}{{V}_{\mathrm{sol}}}\times {10}^{6}=48$

$\Rightarrow {W}_{\mathrm{Mg}}=\frac{48\times 2\times 1000}{{10}^{6}}$

$=48\times 2\times {10}^{-3}g$

${n}_{\mathrm{Mg}}=\frac{{W}_{\mathrm{Mg}}}{24}=\frac{48\times 2\times {10}^{-3}}{24}$

$=4\times {10}^{-3}$

Number of $\mathrm{Mg}$ atoms $=4\times {10}^{-3}\times 6.02\times {10}^{23}=4\times 6.02\times {10}^{20}$

$=4\times 6.02\times {10}^{20}$

$=24.08\times {10}^{20}$

$\therefore x=24.08$

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JEE Main 2022 — Chemistry Physical Chemistry

2022integereasy

Official previous-year question

Held on 26 Jul 2022 · Verified 6 Jul 2026.

Did you get this right?

Solution

$\mathrm{ppm}=\frac{{W}_{{M}_{g}}}{{V}_{\mathrm{sol}}}\times {10}^{6}=48$

$\Rightarrow {W}_{\mathrm{Mg}}=\frac{48\times 2\times 1000}{{10}^{6}}$

$=48\times 2\times {10}^{-3}g$

${n}_{\mathrm{Mg}}=\frac{{W}_{\mathrm{Mg}}}{24}=\frac{48\times 2\times {10}^{-3}}{24}$

$=4\times {10}^{-3}$

Number of $\mathrm{Mg}$ atoms $=4\times {10}^{-3}\times 6.02\times {10}^{23}=4\times 6.02\times {10}^{20}$

$=4\times 6.02\times {10}^{20}$

$=24.08\times {10}^{20}$

$\therefore x=24.08$

Your note

JEE Main Physical Chemistry in other years

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JEE Main 2022 — Chemistry Physical Chemistry

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JEE Main Physical Chemistry in other years

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JEE Main 2022 — Chemistry Physical Chemistry

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Solution

Your note

JEE Main Physical Chemistry in other years

More JEE Main Physical Chemistry questions

Other Chemistry topics for JEE Main

Organic Chemistry

Inorganic Chemistry

Keep practicing Physical Chemistry