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(I) $H_{2} O_{2} + O_{3} \overset{}{\to} H_{2} O + 2 O_{2}$

(II) $H_{2} O_{2} + {Ag}_{2} O \overset{}{\to} 2 Ag + H_{2} O + O_{2}$

Role of hydrogen peroxide in the above reactions is respectively

oxidising in (I) and reducing in (II)

reducing in (I) and oxidising in (II)

reducing in(I) and (II)

oxidising in(I) and (II)

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In acidic medium, H₂O₂ changes ${Cr}_{2} O_{7}^{2 -}$ to CrO₅ which has two (-O-O-) bonds. Oxidation state of Cr in CrO₅ is

-10

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The reaction of aqueous KMnO₄ with H₂O₂ in acidic conditions gives

Mn⁴⁺ and O₂

Mn²⁺ and O₂

Mn²⁺ and O₃

Mn⁴⁺ and MnO₂

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Explanation

The reaction of aqueous KMnO₄ with H₂O₂ in acidic medium is

3H₂SO₄ + 2KMnO₄ + 5H₂O₂ $\to$ 5O₂ + 2MnSO₄ + 8H₂O + K₂SO₄

In the above reaction, KMnO₄ oxidises H₂O₂ to O₂ and itself [ ${MnO}_{4}^{-}$ ] gets reduced to Mn²⁺ ion as MnSO₄. Hence, aqueous solution of KMnO₄ with H₂O₂ yields Mn²⁺ and O₂ in acidic conditions.

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Nascent hydrogen consists of $-$

Hydrogen atoms with excess energy

Hydrogen molecules with excess energy

Hydrogen ions in the excited state

Solvated protons

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Explanation

(A). Hydrogen atoms with excess energy

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Maximum concentration of ortho- $H_{2}$ in ordinary hydrogen is:

75% ortho- $H_{2}$ + 25% para- $H_{2}$

25% ortho- $H_{2}$ + 75% para- $H_{2}$

50% ortho- $H_{2}$ + 50% para- $H_{2}$

99% para- $H_{2}$ + 1% ortho- $H_{2}$

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Explanation

75% ortho- $H_{2}$ + 25% para- $H_{2}$

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Hydrogen will not reduce $-$

heated cupric oxide

heated ferric oxide

heated stannic oxide

heated aluminium oxide

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Explanation

(D). Al $-$ O bond is very strong.

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Chemical A is used for water softening to remove temporary hardness. A reacts with sodium carbonate to generate caustic soda. When ${CO}_{2}$ is bubbled through a solution of A, it turns cloudy. What is the chemical formula of A $-$

${CaCO}_{3}$

$CaO$

$Ca {(OH)}_{2}$

$Ca {({HCO}_{3})}_{2}$

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Explanation

(C). $Ca {(OH)}_{2}$ is used for the softening of temporary hard water.

$Ca {(OH)}_{2} (aq) + {CO}_{2} (g) \overset{}{\to} {CaCO}_{3} (s) + H_{2} O (l)$

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The first ionization energy $(kJ {mol}^{- 1})$ for $H, Li, F, Na$ has one of the following values : $1681, 520, 1312, 495 .$ Which of these values corresponds to that of hydrogen ?

1681

1312

520

485

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Explanation

(B). IE of H is more than that of alkali metals but less than that of F.

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The hydrides ion $H^{-}$ is a stronger base than its hydroxide ion ${OH}^{-}$ . Which of the following reactions will occur if sodium hydride $(NaH)$ is dissolved in water –

$H^{-} (aq) + H_{2} O \to H_{3} O^{-} (aq)$

$H^{-} (aq) + H_{2} O (l) \to {OH}^{-} (aq) + H_{2} (g)$

$H^{-} (aq) + H_{2} O (l) \to No reaction$

$None of these$

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Explanation

(B). $H^{-} (aq) + H_{2} O (l) \to {OH}^{-} (aq) + H_{2} (g) base 1 acid 2 base 2 acid 1$

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Blackened oil planting can be restored into original form by the action of:

Chlorine

${BaO}_{2}$

$H_{2} O_{2}$

${MnO}_{2}$

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Explanation

3. $H_{2} O_{2}$

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