Subject

Chemistry

Class

NEET Class 12

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 Multiple Choice QuestionsMultiple Choice Questions

1.

The radius of hydrogen atom is 0.53 Å. The radius of 3Li2+ is of:

  • 1.27 Å

  • 0.17 Å

  • 0.57 Å

  • 0.99 Å


B.

0.17 Å

The radius of hydrogen atom = 0.53 Å.

3Li+2 ion consists of only 1 electron but it has 3 protons in its nucleus. Hence, its electron fall is three times more attracted from nucleus as compared to hydrogen atom. Thus, the radius of 3Li+2 is = 0.533 = 0.17 Å


2.

Which one of the following pair shows Buffer's solution?

  • NaCl + NaOH

  • CH3COONa + CH3COOH

  • CH3COOH + CH3COONH4

  • H2SO4 + CuSO4


B.

CH3COONa + CH3COOH

Buffer's solutions are the solutions which resists the chnages in its pH value on addition of small amount of a base or an acid. 

Among all the given options, CH3COOH and CH3COONa are the example of Buffer's solutions because they are the combination of weak acid and salt of strong base.


3.

Which is correct for an enothermic reaction?

  • H is positive

  • H is negative

  • E is negative

  • H= zero


A.

H is positive

For an endothermic reactions H is positive because in endothermic reaction heat is always absorbed.


4.

The correct sequence of hybridisation of methane, ethene and acetylene is :

  • sp, sp2, sp3

  • sp2, sp3, sp

  • sp3, sp2, sp

  • sp3, sp, sp2


C.

sp3, sp2, sp

The correct sequence of hybridisation of methane, ethene and ethyne is sp3, sp2 and sp.


5.

By dissolving 5 g substance in 50 g of water, the decrease in freezing point is 1.2°C. The gram molal depression is 1.85°C. The molecular weight of substance is :

  • 105.4

  • 118.2

  • 137.2

  • 154.2


D.

154.2

We know,

m = 1000 Kf × wTW

Here, T = 1.2°C; Kf = 1.85°

           w = 5 gm;  W = 50 gm

 m = 1000 × 1.85 × 51.2 × 50 = 154.2

154.2 is the molecular weight of a substance.


6.

35.4 ml of HCl is required for the neutralization of a solution containing 0.275 g of sodium hydroxide. The normality of hydrochloric acid is ?

  • 0.97 N

  • 0.142 N

  • 0.194 N

  • 0.244 N


C.

0.194 N

We know,

1 gm equivalent weight of NaOH = 40 gm

                     40 gm of NaOH = 1 gm eq. of NaOH

                0.275 gm of NaOH = 140× 0.275 

                                               = 140× 0.274 × 1000

                                               = 6.88 m eq.

                                    N1V1(HCl) = N2V2(NaOH)

                                N1 × 35.4 = 6.88 (meq = NV)

                                           N1 = 0.194


7.

Which of the following chloride is water insoluble?

  • HCl

  • AgCl

  • Both 'a' and 'b'

  • None of these


B.

AgCl

AgCl is insoluble in water because the forces favouring the formation of silver hydroxide are too weak to break the ionic bonds between silver and chlorine.


8.

Which one of the following has unit positive charge and 1 amu mass ?

  • Electron

  • Neutron

  • Proton

  • None of these


C.

Proton

The proton has unit positive charge (+1.602 × 10-19 Coulombs) and its mass is 1.007 amu, i.e. 1.677 × 10-27 kg).


9.

The value of amu is which of the following ?

  • 1.57 × 10-24 kg

  • 1.66 × 10-24 kg

  • 1.99 × 10-23 kg

  • 1.66 × 10-27 kg


D.

1.66 × 10-27 kg

amu is represented by atomic mass unit. It is used in place of unified mass unit.

1 amu = 1 avogram = 1 aston = 1 dalton

1 amu = 112 × mass of C-12 atom

          = 112 × 1.9924 × 10-23 gm

          = 1.66 × 10-24 gm

          = 1.66 × 10-27 kg


10.

The molecule having largest dipole moment among the following is :

  • CHI3

  • CH4

  • CHCl3

  • CCl4


C.

CHCl3

Among all the given options, CHCl3 molecule has largest dipole moment.