JEE Main · 2019 · 08 Apr 2019 · Shift 1 · Hydrogen

WhatsApp Email

100 mL of a water sample contains 0.81 g of calcium bicarbonate and 0.73 g of magnesium bicarbonate. The hardness of this water sample expressed in terms of equivalents of

CaCO_{3}

is:
(molar mass of calcium bicarbonate is

162 gmol^{- 1}

and magnesium bicarbonate is 146 g

mol^{- 1}

)

(A) $10, 000 ppm$ ✓ Correct
(B) $1, 000 ppm$
(C) $5, 000 ppm$
(D)100 ppm

Answer: (A)

Solution

Hardness is reported as the equivalent amount of

CaC O_{3}

, so convert each salt. Calcium bicarbonate gives

\frac{0.81}{162} = 0.005

mol and magnesium bicarbonate

\frac{0.73}{146} = 0.005

mol, each equivalent to one mole of

CaC O_{3}

, so together they amount to

0.01

mol, or

0.01 \times 100 = 1.0

g of

CaC O_{3}

. Sitting in

100

mL, essentially

100

g, of water, the hardness is

\frac{1.0}{100} \times 1 0^{6} = 10, 000

ppm.

JEE Main · 2019 · 08 Apr 2019 · Shift 1 · Single correct option

Practise more: all JEE Main PYQs on Hydrogen →

More JEE Main questions on Hydrogen

Which of the following can reduce decomposition of $H_{2} O_{2}$ on exposure to light
JEE Main 2023View solution →
Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R.
Assertion A: Physical properties of isotopes of hydrogen are different.
Reason R: Mass difference between isotopes of hydrogen is very large.
In the light of the above statements …
JEE Main 2023View solution →
Given below are two reactions, involved in the commercial production of dihydrogen $(H_{2})$ .
The two reactions are carried out at temperature " $T_{1}$ " and " $T_{2}$ " respectively …
JEE Main 2023View solution →
Given below are two statements :

Statement-I : Methane and steam passed over a heated Ni catalyst produces hydrogen gas.
Statement-II : Sodium nitrite reacts with $NH_{4} Cl$ to give $H_{2} O, N_{2}$ and NaCl .
In the light of the …
JEE Main 2023View solution →
Which hydride among the following is less stable?
JEE Main 2023View solution →
Given below are two statements:

Statement-I Permutit process is more efficient compared to the synthetic resin method for the softening of water.
Statement-II: Synthetic resin method results in the formation of soluble sodium salts.

In the light of the above statements, choose …
JEE Main 2023View solution →