91.

Which of the following is not correct regarding the elecolytic preparation of H₂O₂?

• Lead is used as cathode

• 50% H₂SO₄ is used

• Hydrogen is liberated at anode

• Sulphuric acid undergoes oxidation

What are the values of n₁ and n₂ respectively for ${\mathrm{H}}_{\mathrm{\beta }}$ line in the Lyman series of hydrogen atomic spectrum 44 ?

• 3 and 5

• 2 and 3

• 1 and 3

• 2 and 4

The most probable velocity (in cm/s) of hydrogen molecule at 27$°$C will be

• 19.3 x 10⁴

• 17.8 x 10⁴

• 24.93 x 10⁹

• 17.8 x 10⁸

Heavy water is

• CaSO₄

• water contain CaSO₄, MgSO₄

• D₂O

• water contain CaCO₃

The number of moles of oxygen obtained by the electrolytic decomposition of 108 g water is

• 2.5

• 3

• 5

• 7.5

Presence of phosphoric acid or glycerine or acetanilide retards the decomposition of H₂O₂ .This is an example of:

• Positive catalysis.

• Negative catalysis.

• Auto catalysis.

• Induced catalysis.

For binary hydrides of formula M x n the value of n can be fractional for:

• salt like hydrides

• interstitial hydrides

• covalent hydrides

• polymeric hydrides

The reaction of HBr with  in the presence of peroxide will give

• 

• 

• 

• CH₃CH₂CH₂CH₂Br

Hardness of water is due to presence of salts of:

• Na⁺ and K⁺

• Ca²⁺ and Mg²⁺

• Ca²⁺ and K⁺

• Ca²⁺ and Na⁺

H₂O is liquid while H₂S is a gas due to

• covalent bonding

• molecular attraction

• H-bonding

• both H-bonding and molecular attraction