21.

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 homologue of ethyne is

• C₂H₂

• C₂H₆

• C₃H₈

• C₃H₄

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

Which of the following carbonates decomposes readily at low temperatures ?

• Na₂CO₃

• K₂CO₃

• Li₂CO₃

• Rb₂CO₃

The compounds formed at anode in the electrolysis of an aqueous solution of potassium acetate, are

• C₂H₆ and CO₂

• C₂H₄ and CO₂

• CH₄ and H₂

• CH₄ and CO₂

What is the electrode potential (in V) of the following electrode at 25°C ?

Ni²⁺ (0.1 M) | Ni(s)

(Standard reaction potential of Ni²⁺ | Ni is -0.25V, $\frac{2.303 \mathrm{RT}}{\mathrm{F}} = 0.06$)

• -0.28V

• -0.34V

• -0.82V

• -0.22V

Which of the following is not correct?

• Al reacts with NaOH and liberate H₂

• AlCl₃ is a Lewis acid

• Al is used in the manufacture of electrical cables

• NaOH is used during Hall's process of purification of bauxite

To dissolve argentite ore which of the following is used?

• Na[Ag(CN)₂]

• NaCN

• NaCl

• HCl

If 50% of a radioactive substance dissociates in 15 min, then the time taken by substance to dissociate 99% will be

• 50 min

• 100 min

• 99 min

• 150 min

Which of the following does not have coordinate bond?

• SO₂

• HNO₃

• H₂SO₄

• HNO₂