Physical properties in which D₂O differs from H₂O is/are:

1. solubility of salts in heavy water is less than in ordinary water

2. all physical constants of D₂O are higher than H₂O. 

3. heavy water is almost 11% denser than light (normal) water.

4. all of the above.

Industrial preparation of H₂​O₂ is-

1. By the action of dilute sulphuric acid: BaO₂​.8H_2​O(s) + H₂​SO₄​(aq) → BaSO₄​(s) + H₂​O₂​(aq) + 8H₂​O(l)

2. By the action of carbon dioxide: BaO₂​ + H₂​O + CO₂​ → BaCO₃ ​+ H₂​O₂​

3. By the action of phosphoric acid: 3BaO₂​ + 2H₃​PO₄​ → Ba₃​(PO₄​)₂​ + 3H₂O₂​

4. ${\mathrm{H}}_2{\mathrm{O}}_2<mspace\; width="1em"></mspace>+<mspace\; width="1em"></mspace>2<mspace\; width="1em"></mspace>\mathrm{ethylanthraquinol}<mspace\; width="1em"></mspace>\underset{{\mathrm{H}}_2/\mathrm{Pd}}{\overset{{\mathrm{O}}_2<mspace\; width="1em"></mspace>\left(\mathrm{air}\right)}{\rightleftharpoons }}<mspace\; width="1em"></mspace>{\mathrm{H}}_2{\mathrm{O}}_2<mspace\; width="1em"></mspace>+<mspace\; width="1em"></mspace>\mathrm{Oxidised}<mspace\; width="1em"></mspace>\mathrm{Products}$

Structures of  and ${}^{}\mathrm{O\; is/are}$

$$ {}^{}{}^{}$$ {}^{}\mathrm{O has\; a\; bent\; structure\; .}$$

$$ \mathrm{2.}$$

The correct order of increasing electrical conductance is -
1. BeH₂ > CaH₂ > TiH₂
2. BeH₂ < CaH₂ > TiH₂
3. TiH₂ < BeH₂ < CaH₂
4. BeH₂ < CaH₂ < TiH₂

The correct order of increasing reducing nature is -

1. NaH > H₂O < MgH₂

_{2. ${\mathrm{H}}_2\mathrm{O}$ > ${\mathrm{MgH}}_2$> NaH}

_{3. ${\mathrm{H}}_2\mathrm{O}$< ${\mathrm{MgH}}_2$ < NaH}

_{4. ${\mathrm{H}}_2\mathrm{O}$ $\simeq$ ${\mathrm{MgH}}_2$ < NaH}

Atomic hydrogen combines with almost all elements but molecular hydrogen does not because

1. Atomic hydrogen is highly unstable molecular, hydrogen is almost inert at room temperature.

2. Atomic hydrogen is highly inert, molecular hydrogen is almost unstable at room temperature.

3. Atomic hydrogen and molecular hydrogen are unstable.

4. Atomic hydrogen and molecular hydrogen are inert.

Choose reactions to explain the amphoteric nature of water.

$1)<mspace\; width="1em"></mspace>{\mathrm{H}}_2\mathrm{O}(\mathrm{l})+{\mathrm{NH}}_3(\mathrm{aq})\to {\mathrm{OH}}^{-}(\mathrm{aq})+{\mathrm{NH}}_4^{+}(\mathrm{aq})$
$2)<mspace\; width="1em"></mspace>{\mathrm{H}}_2\mathrm{O}(\mathrm{l})+{\mathrm{H}}_2\mathrm{S}(\mathrm{aq})\to {\mathrm{H}}_3{\mathrm{O}}^{+}(\mathrm{aq})+{\mathrm{HS}}^{-}(\mathrm{aq})$
$3)<mspace\; width="1em"></mspace>\mathrm{a}<mspace\; width="1em"></mspace>\&<mspace\; width="1em"></mspace>\mathrm{b}$
$4)<mspace\; width="1em"></mspace>\mathrm{none}$

H⁺ ions always get associated with other atoms or molecules due to -

The amount of $H_2{O}_2<mspace\; width="1em"></mspace>$ present in 1 L of 1.5 N $H_2{O}_2<mspace\; width="1em"></mspace>$ solution is:

1. 2.5 g

2. 25 g

3. 3.0 g

4. 8.0 g

Hard water can be produced by -

(1) Saturation of water with CaSO₄

(2) Addition of $N{a}_{2}S{O}_4$  to water

(3) Saturation of water with CaCO₃

(4) Saturation of water with MgCO₃