Hydrogen

This is a multiple choice answer as classified in NCERT Exemplar

option (iv)

Loss of an electron from a hydrogen atom results in a nucleus of very small size as compared to other atoms or ions. Due to its small size it cannot exist free.

Loss of the electron from hydrogen atom results in nucleus size (H⁺) of 1.5 * 10^-3. This is extremely small as compared to normal atomic and ionic sizes of 50 to 200 pm. As a consequence, H⁺ does not exist freely and is always associated with other atoms or molecules.

This is a multiple choice answer as classified in NCERT Exemplar

option (ii)

Its tendency to gain a single electron in its valence shell to attain stable electronic configuration.

Like halogens (with ns²np⁵ configuration belonging to the seventeenth group of the periodic table), it is short by one electron to the corresponding noble gas configuration, helium (ls²).

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H₂O (l)+NH₃ (aq) → OH^- (aq)+NH₄⁺ (aq)

H₂O (l)+H₂S (aq) → H₃O⁺ (aq)+HS^- (aq)

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2F₂ (g)+2H₂O → 4H⁺ (aq)+4F^- (aq)+O₂ (g)

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In water hybridisation of oxygen is sp³. Angle should be109^o (approx.) but due to LP - LP repulsion bond angle reduces to 104.5°.

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Because H₂SO₄ can activate the decomposition of H₂O₂.

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With soap, hard water generates scum/precipitate. Soap containing sodium stearate (C1₁₇H₃₅COONa) interacts with hard water to form calcium and magnesium stearate (Ca/Mg stearate). As a result, it is unsuitable for laundering. Because of the deposition of salts in the form of scale, it is also hazardous to boilers.

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Hydrogen peroxide is stored in wax lined bottles because decomposes slowly on exposure to light.

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Hydrogen peroxide cannot be concentrated by heating as it can cause bumps on heating. It can be extracted with water and concentrated to ~30% (by mass) by distillation under reduced pressure. It can be further concentrated to ~85% by careful distillation under low pressure. The remaining water can be frozen out to obtain pure H₂O₂.

This is a short answer type question as classified in NCERT Exemplar

Water has a significantly higher boiling point than hydrogen sulphide because of the presence of strong hydrogen bonds between water molecules, which are absent in hydrogen sulphide due to the lower electronegativity of sulfur compared to oxygen; this means more energy is required to separate water molecules, resulting in a higher boiling point.