11.

In III group precipitation, NH₄Cl is added before adding NH₄OH to

• decrease conc. of OH^-

• prevent interference of PO${}_4^{3-}$

• increase conc. of Cl^-

• increase conc. of OH^- ion

What is the wave number of 4^th line in Balmer series of hydrogen spectrum ? (R =1,09,677 cm^-1)

• 24630 cm^-1

• 24360 cm^-1

• 24730 cm^-1

• 24372 cm^-1

Disperse phase and dispersion medium in butter are respectively

• solid and liquid

• liquid and solid

• liquid and liquid

• solid and solid

The atomic number of an element 'M' is 26. How many electrons are present in the M-shell of the element in its M³⁺ state ?

• 11

• 15

• 14

• 13

In which of the following pairs, both molecules possess dipole moment ?

• CO₂, SO₂

• BCl₃, PCl₃

• H₂O, SO₂

• CO₂, CS₂

9.2 g N₂O₄ is heated in a 1L vessel till equilibrium state is established

N₂O₄ (g) $\rightleftharpoons$ 2NO₂ (g)

In equilibrium state 50% Np4 was dissociated, equilibrium constant will be (mol. wt. of N₂O₄ = 92)

• 0.1

• 0.4

• 0.3

• 0.2

SiO₂ is reacted with sodium carbonate. What is the gas liberated ?

• CO

• O₂

• CO₂

• O₃

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

In an oxidation-reduction reaction, MnO${}_4^{-}$ ion is converted to Mn²⁺. What is the number of equivalents of KMnO₄ (mol. wt.= 158) present in 250 mL of 0.04 M KMnO₄ solution ?

• 0.02

• 0.05

• 0.04

• 0.07

Oxidation state of oxygen in F₂O is

• +1

• -1

• +2

• -2