21.

In Fischer-Ringe's method of separation of nobles gas mixture from air ....... is used

• 90% CaC₂ + 10% CaCl₂

• coconut charcoal

• soda lime + potash solution

• 90% CaCO₃ + 10% urea

A complex compound of Co³⁺ with molecular formula CoCl_x. yNH, gives a total of 3 ions when dissolved in water. How many Cl^- ions satisfy both primary and secondary valencies is this complex?

• 3

• 1

• 4

• zero

Observe the following statements regarding purification of bauxite

I. During Hall's process, silica is removed as Si (vapour).

II. Bauxite ore contaminated with Fe₂O₃ is purified in Baeyer's process.

III. During Serpeck's process, AlN is formed.

The correct answeris

• I, II and III are correct

• Only I and II are correct

• Only I and III are correct

• Only II and III are correct

Which of the following is an example for heterogeneous catalysis reaction ?

• $2{\mathrm{SO}}_2\left(\mathrm{g}\right) + {\mathrm{O}}_2\left(\mathrm{g}\right) \stackrel{\mathrm{NO}\left(\mathrm{g}\right) }{\to }2{\mathrm{SO}}_3 \left(\mathrm{g}\right)$

• Hydrolysis of aqueous sucrose solution in the presence of aqueous mineral acid

• $2{\mathrm{H}}_2{\mathrm{O}}_2 \left(\mathrm{l}\right) \stackrel{\mathrm{Pt}\left(\mathrm{s}\right) }{\to }2{\mathrm{H}}_2\mathrm{O} \left(\mathrm{l}\right) + {\mathrm{O}}_2 \left(\mathrm{g}\right)$

• Hydrolysis of liquid in the presence of aqueous mineral acid

The half-lives of two radioactive nuclides A and B are 1 and 2 min respectively. Equal weights of A and B are taken separately and allowed to disintegrate for 4min. What will be the ratio of weights of A and B disintegrated?

• 1:2

• 5:4

• 1:2

• 1:3

Identify the correct order in which the covalent radius of the following elements increases

                    (I)Ti, (II) Ca, (III) Sc

• (I), (II), (III)

• (III), (II), (I)

• (II), (I), (III)

• (I), (III), (I)

The vapour pressure of water at 23°C is 19.8 mm, 0.1 mole of glucose is dissolved in 178.2 g ofwater. What is the vapour pressure (in mm) ofthe resultant solution?

• 19.0

• 19.602

• 19.402

• 19.202

What is the quantity of electricity (in Coulombs) required to deposit all the silver from 250 mL of 1 M AgNO₃ solution?

• 2412.5

• 24125

• 4825.0

• 48250

Which of the following is not correct?

• Aqueous solution of NaCl is an electrolyte

• The units of electrochemical equivalent are g-Coulomb

• It the Nernst equation, n represents the number of electrons transferred in the electrode reaction.

• Standard reduction potential of hydrogen electrode is zero volt

Observe the following reaction 2A + B → C. The rate of formation of C is 2.2 × 10^-3 mol L^-1min^-1. What is the value of - $\frac{\mathrm{d}\left[\mathrm{A}\right]}{\mathrm{dt}}$ (in mol L^-1min^-1)?

• 2.2 × 10^-3 

• 1.1 × 10^-3 

• 4.4 × 10^-3 

• 5.5  × 10^-3