The disperse phase, dispersion medium and nature of colloidal sol

Subject

Chemistry

Class

JEE Class 12

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 Multiple Choice QuestionsMultiple Choice Questions

21.

Which of the following reactions does not liberate gaseous product ?

  • AlCl3 + NaOH →

  • NaOH + P(white) + H2O →

  • Al + NaOH 

  • Zn + NaOH 


22.

CH3CH2OH Step- 1Cl2 CH3CHO Step-23Cl2 Cl3CCHO

In the above reaction, the role of Cl2 in Step-1 and Step-2 respectively is:

  • oxidation, chlorination

  • reduction, chlorination

  • oxidation, addition

  • reduction,substitution


23.

The number of sigma (σ) and pi (π) bonds present in benzene respectively are :

  • 12, 6

  • 6, 6

  • 6, 12

  • 12, 3


24.

The standard reduction potentials of Zn2+| Zn, Cu2+| Cu and Ag+| Ag are respectively -0.76, 0.34 and 0.8 V. The following cells were constructed :

(1) Zn | Zn2+ || Cu2+ | Cu

(2) Zn | Zn2+ || Ag+ | Ag

(3) Cu | Cu2+ || Ag+ |Ag

What is the correct order of Ecell° of these cells?

  • 2 > 3 > 1

  • 2 > 1 > 3

  • 1 > 2 > 3

  • 3 > 1 > 2


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25.

What is the time (in sec) required for depositing all the silver present in 125 mL of 1 M AgNO3 solution by passing a current of 241.25 A? (1F = 96500 coulombs)

  • 10

  • 50

  • 1000

  • 100


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26.

The disperse phase, dispersion medium and nature of colloidal solution (lyophilic or lyophobic) of 'gold sol' respectively are :

  • solid, solid, lyophobic

  • liquid, liquid, lyophobic

  • solid, liquid, lyophobic

  • solid, liquid, lyophilic


C.

solid, liquid, lyophobic

The disperse phase, dispersion medium and nature of colloidal solution of 'gold sol'  are solid, liquid and lyophobic respectively. 

Colloidal solution of gold is obtained when dispersed phase is solid and dispersion medium is liquid. Substances like metals cannot be brought into the colloidal state simply by bringing them in contact with water and therefore, special methods are devised for the purpose. Hence, they are known as hydrophobic or lyophobic colloids.


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27.

Electrolysis of X gives Y at anode. Vacuum distillation of Y gives H2O. The number of peroxy (O-O) bonds present in X and Y respectively are :

  • 1, 1

  • 1, 2

  • zero, 1

  • zero, zero


28.

AB is an ionic solid. The ionic radii of A+ and B- are respectively rc and ra. Lattice energy of AB is proportional to :

  • rcra

  • (rc + ra)

  • rarc

  • 1rc + ra


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29.

The rate constant of a first order reaction at 27°C is 10-3 min-1. The temperature coefficient of this reaction is 2. What is the rate constant (in min-1 ) at 17°C for this reaction ?

  • 10-3

  • 5 × 10-4

  • 2 × 10-3

  • 10-2


30.

What is the correct order of occurrence (% by weight) in air of Ne, Ar and Kr ?

  • Ne > Ar > Kr

  • Ar > Ne > Kr

  • Ar > Kr > Ne

  • Ne > Kr > Ar


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