JEE Main 2019ChemistryHydrogenHardMCQ

JEE Main 2019 — Hydrogen Question with Solution

JEE Main 2019 (12 Jan Shift 1)

Question

What is the hardness of a water sample (in terms of equivalents of CaCO3) containing 10-3M CaSO4?

(Molar mass of CaSO4=136 g  mol-1)

Choose an option

Show full solutionCorrect option: D
Correct answer
D100 ppm

Step-by-step explanation

As 1 L solution have 10-3 mol CaSO4

Eq.  of CaSO4=eq.  of CaCO3

In 1 L solution

nCaSO4×v.f=nCaCO3×v.f.

10-3×2=nCaCO3×2

nCaCO3=10-3 mol in 1 L

∴WCaCO3=100×10-3g   in 1 L solution

∴ hardness in terms of CaCO3

=WCaCO2Wtotal×106=100×10-3 g1000 g×106=100 ppm

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About this question

This is a previous-year question from JEE Main 2019, covering the Hydrogen chapter of Chemistry. PrepSharp catalogues every PYQ from JEE Main with a verified answer key and step-by-step solution prepared by IIT alumni — so you can search by chapter, topic or year and revise efficiently.