Tag: hard water and soft water

Questions Related to hard water and soft water

The reactions of heavy water are slow. The reason is :

chemistry hard water and soft water heavy water study of heavy water hydrogen and its compounds

  1. heavy water is associated.

  2. heavy water is dissociated.

  3. heavy water is of higher mass.

  4. heavy water is of lower mass.

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Correct Option: C
Explanation:

As Deuterium contains one extra neutron, so heavy water has higher molecular mass than water and because of that it is less reactive.

A molecule of heavy water has two deuterium atoms in place of the two protium atoms of ordinary "light" water. The weight of a heavy water molecule, however, is not substantially different from that of a normal water molecule,

Deuteromethane can be prepared if $D _{2}O$ reacts with:

chemistry hard water and soft water heavy water study of heavy water hydrogen and its compounds

  1. $Al _{4}C _{3}$

  2. $CaC _{2}$

  3. both A and B

  4. none of the above

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Correct Option: A
Explanation:
On hydrolysis of $Al _{4}C _{3}$ methane forms, similarly $D _2O$ reacts with $Al _{4}C _{3}$ and deuteromethane forms as the product.

The weight of one mole of heavy water is:

chemistry hard water and soft water heavy water study of heavy water hydrogen and its compounds

  1. $18$ gm

  2. $20$ gm

  3. $19$ gm

  4. $21$ gm

Show answer
Correct Option: B
Explanation:
 Deuterium is called as heavy water,

As atomic mass of Deuterium is 2 and atomic mass of oxygen is 16

So Molar mass of $D _2O$ is = $2\times2 +1\times 16= 20$

Weight of $1$ mole of ${ D } _{ 2 }O =$ Molecular mass of ${ D } _{ 2 }O = 20$ gm

Option B is correct.

$D _2O$ ( heavy water) and $H _2O$ differ in following except :

chemistry hard water and soft water heavy water study of heavy water hydrogen and its compounds

  1. Freezing point

  2. Density

  3. Ionic product of water

  4. None of these

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Correct Option: D

Deuterio hydrate of magnesium sulphate contains how many molecules of heavy water?

chemistry hard water and soft water heavy water study of heavy water hydrogen and its compounds

  1. $2\ D _{2}O$

  2. $3\ D _{2}O$

  3. $10\ D _{2}O$

  4. $7\ D _{2}O$

Show answer
Correct Option: D
Explanation:

Deuterio hydrate of magnesium sulphate is $MgSO _4.7D _2O$. So, 7 molecules of heavy water molecules is present.

$4D _{2}O+3Fe \xrightarrow{Red:hot}Fe _{3}O _{4}+gas$. The gas produced in the above reaction is:

chemistry hard water and soft water heavy water study of heavy water hydrogen and its compounds

  1. $O _{2}$

  2. $H _{2}$

  3. $D _{2}$

  4. $T _2$

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Correct Option: C
Explanation:

Reaction of process:
$4D _{2}O+3Fe \xrightarrow{Red:hot}Fe _{3}O _{4}+ 4D _2$.

Heavy water is not used for drinking because:

chemistry hard water and soft water heavy water study of heavy water hydrogen and its compounds

  1. it is poisonous

  2. it is costly

  3. its physiological action is different from ordinary water

  4. its chemical properties different from ordinary water

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Correct Option: C
Explanation:

As molecular mass of heavy water is higher than water so its physiological action is different from ordinary water and because of that reason it can not be used as drinking water.

Which of the following are correctly matched?


$(a):D _{2}O-$ Hard water

$(b):H _{2}O-$ Heavy water

$(c):D-$ Heavy hydrogen

$(d):BaO _{2}.8H _{2}O-$ True peroxide

chemistry hard water and soft water heavy water study of heavy water hydrogen and its compounds

  1. $a, b, c, d$ are correct

  2. $c, d$ are correct

  3. $a, b, c$ are correct

  4. $a, c, d$ are correct

Show answer
Correct Option: B
Explanation:

$D _{2}O-$ Heavy water


$H _{2}O-$ Ordinary water

$D-$ Heavy hydrogen (As atomic mass of $D$ is higher than $H$)

$BaO _{2}.8H _{2}O-$ True peroxide.

Heavy water $(D _{2}O)$ freezes at:

chemistry hard water and soft water heavy water study of heavy water hydrogen and its compounds

  1. $0^\circ C$

  2. $-3.8^\circ C$

  3. $0.8^\circ C$

  4. $3.82^\circ C$

Show answer
Correct Option: D
Explanation:

Freezing point of heavy water is $3.82^oC$. Heavy water is a form of water that contains a larger than normal amount of the hydrogen isotope deuterium, rather than the common hydrogen-$1$ isotope that makes up most of the hydrogen in regular water.

Which of the following is not true?

chemistry hard water and soft water heavy water study of heavy water hydrogen and its compounds

  1. Ordinary water is electrolysed more rapidly than $D _{2}O$

  2. $D _{2}O$ freezes at lower temperature than $H _{2}O$

  3. Reaction between $H _{2}$ and $Cl _{2}$ is much faster than $D _{2}$ and $Cl _{2}$

  4. Bond dissociation energy for $D _{2}$ is greater than $H _{2}$

Show answer
Correct Option: B
Explanation:

As D contains one extra neutron so heavy water has higher molecular mass than water and its electrolysis takes more time.
Also because of that it is less reactive and bond dissociation energy for $D _{2}$ is greater than $H _{2}$.
And $D _{2}O$ freezes (3.8C) at higher temperature than $H _{2}O$