Subject

Chemistry

Class

NEET Class 12

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 Multiple Choice QuestionsMultiple Choice Questions

11.

The correct set of quantum numbers for the unpaired electron of a chlorine atom is :

  • 2 , 0 , 0 , +12

  • 2 , 1 , -1 , +12

  • 3 , 1 , -1 , ±12

  • 3 , 0 , 0 , ±12


C.

3 , 1 , -1 , ±12

17Cl = 1s2 2s2 2p6 3s2 3p5

One unpaired electron is present in 3p orbital

    3p

r = 3     m = -1

l = 1      s = ±12


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12.

A 25 W bulb emits monochromatic yellow light of wavelength of 0.57 μm. Calculate the rate of emission of quanta per second.

  • 7.169 x 1019

  • 4.569 x 1019

  • 8.579 x 1019

  • 9.662 x 1019


A.

7.169 x 1019

25 watt = 25 Js-1

E = NHv = NHcλ

25 = N × 6.626 × 10-34 × 3 × 1080.57 × 10-6

N = 7.169  x 1019 quanta s-1


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13.

When 2.495 g of CuSO· x H2O (molar mass 249.5) is heated, 0.05 mole of H2O is lost. Therefore , x is :

  • one

  • three

  • five

  • seven


C.

five

Number of moles of CuSO4 . xH2O = 2.495249.5 = 0.01 mole

 Moles of H2O = 0.01 x mole

= 0.05 mole

x = 5


14.

Each NH3 molecule has six other NH3 molecules as nearest neighbours in solid state ; H of sublimation of NH3 molecule at the m.p. is 30.8 kJ mol-1 and in the absence of H-bonding estimated Ml of sublimation is 14.4 kJ mol-1 .Hence , strength of H-bond in solid NH3 is :

  • 5.47 kJ mol-1

  • 10.93 kJ mol-1

  • 16.40 kJ mol-1

  • - 16.40 kJ mol-1


A.

5.47 kJ mol-1

Total strength of all H-bonds :

= 30.8- 14.4

= 16.4kJ mol-1

There are six nearest neighbours, but each hydrogen bond involves 2 molecules. Hence, effective neighbours = 3.

Hence , strength of H-bond ;

16.43 = 5.47 KJ mol-1.


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15.

Which of the following compounds is the weakest Bronsted base ?


C.

Compounds and both have a stronger tendency to accept a proton and hence are stronger Bronsted bases than phenol (c) and alcohol (d). Since, phenol is more acitive than alcohol , therefore, phenol has the least tendency to accept a proton and hence it is the weakest Bronsted base.


16.

Which one ofthe following is not tetrahedral in shape ?

  • SiCl4

  • NH4+

  • CH4

  • SF4


D.

SF4

SF4 has trigonal bipyramid geometry since it has sp3d hybridisation.


17.

When 6 g of a monobasic acid is dissolved in 100 mL solution , it is l N. What is equivalent mass of the acid ?

  • 20 g equiv-1

  • 40 g equiv-1

  • 60 g equiv-1

  • 80 g equiv-1


C.

60 g equiv-1

From w = NEV1000

E = w × 1000N × V = 6 × 10001 × 100

= 60 g equiv-1


18.

N2O is isoelectronic to CO2 and N3-. Which of the following is the structure of N2O ?

  • N-O-N

  • N-N-O


C.

N-N-O

N2O is isoelectronic with COand N3. Hence, its structure is linear i.e. , N=N ➔ 0.


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19.

Calculate the radius of a water molecule assuming to be spherical (density= 1 g mL-1) :

  • 1.925 10-8 cm

  • 1.925x 10-9 cm

  • 1.925 10-10 cm

  • 1.925 10-11 cm


A.

1.925 10-8 cm

Mass of one molecule = 186.02 × 1023 g

Volume of one molecule = 186.02 ×1023 × 1

= 3.0 x 10-23

43 πr3 = 3.0 x 10-23

r33 × 3.0 × 10-23 × 74 × 22

r = = 1.925 x 10-8 cm


20.

Number of lone pair in XeOF4 is :

  • zero

  • one

  • two

  • three


B.

one

Number of lone pair in XeOF4 is one ,

XeOF4 (sp3d2 hybridisation)


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