Diborane (B₂H₆) reacts independently with O₂ and H₂O to produce, respectively:

• B₂O₃ and H₃BO₃

• H₃BO₃ and B₂O₃

• B₂O₃ and [BH₄]^-

• HBO₂ and H₃BO₃

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 CaCO₃ is: (molar mass of calcium bicarbonate is 162 g mol^-1 and magnesium bicarbonate is 146 g mol^-1)

• 1,000 ppm

• 100 ppm

• 10,000 ppm

• 5000 ppm

73.

Which of the following statement about hydrogen is incorrect?

• Hydrogen never acts as cation in ionic salts

• Hydronium ion, H₃O⁺ exist freely in solution

• Dihydrogen does not act as a reducing agent

• Dihydrogen does not act as a reducing agent

The reaction of aqueous KMnO₄ with H₂O₂ in acidic conditions gives.

• Mn⁴⁺ and O₂

• Mn²⁺ and O₂

• Mn²⁺ and O₃

• Mn²⁺ and O₃

A hydrogen gas electrode is made by dipping platinum wire in a solution of HCl of pH =10 and by passing hydrogen gas through the platinum wire at 1 atm pressure. The oxidation potential of electrode would be

• 0.0591 V

• 0.59 V

• 0.118 V

• 0.118 V

Which one of the following molecular hydrides acts as a Lewis acid? 

• NH₃

• H₂O

• B₂H₆

• B₂H₆

Some statement about heavy water are given below

A) Heavy water is used as a moderator in nuclear reactors.

B) Heavy water is more associated than ordinary water.

C) Heavy water is more effective solvent than ordinary

• A and B

• A, B and C

• B and C

• B and C

In which case is a number of molecules of water maximum?

• 18 mL of water

• 0.18 g of water

• 10^-3 mol of water

• 0.00224 L of water vapours at 1 atm and 273K

Which one of the following reactions does not form gaseous product?

• PbO₂ + H₂O₂ $\to$

• Acidified KMnO₄ + H₂O₂ $\to$

• PbS + H₂O₂ $\to$

• Cl₂ + H₂O₂ $\to$

$$\begin{gathered} {\mathrm{SF}}_4 \stackrel{\mathrm{Hydrolysis}}{\to } \mathrm{X} +\hspace{0.17em}\mathrm{Y} \\ \mathrm{X} + {\mathrm{H}}_2\mathrm{S} \to \mathrm{Z} \end{gathered}$$

Here, Z is

• SO₃

• colloidal sulphur

• gaseous sulphur

• solid sulphur