Subject

Chemistry

Class

NEET Class 12

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 Multiple Choice QuestionsMultiple Choice Questions

1.

Which of the following is correct?

  • The pH of one litre solution containing 0.49 g of H2SO4 is 2.0

  • The conjugate base of H2S is S2-

  • BF3 is a Lewis base

  • Phenolphthalein is colourless in basic medium


A.

The pH of one litre solution containing 0.49 g of H2SO4 is 2.0

w = 0.49 gm

E = 49 

V = 1000 mL

 N =w × 1000E . V = 0.49 × 100049 × 1000 = 0.01N [H+] = 0.01 pH = - log [H+]            = - log (1 × 10-2)            = 2


2.

What is the wavelength (in m) of a particle of mass 6.62 x 10-29 g moving with a velocity of 103 ms-1?

  • 6.62 x 10-4

  • 6.62 x 10-3

  • 10-5

  • 105


C.

10-5

According to de-Broglie equation

λ= hmv   = 6.62 × 10-346.62 × 10-29 × 10-3 × 103 = 10-5 m


3.

What is the equation for the equilibrium constant (Kc) for the following reaction?

12A(g) + 13B(g) T(K) 23C(g)

  • Kc = A12 B13C32

  • Kc = C32A2 B3

  • Kc = C23A12B13

  • Kc = C23A12+B13


C.

Kc = C23A12B13

12A(g) + 13B(g) T(K) 23C(g)

Equilibrium constant, KcRate productRate of reactant

                               KcC23A12B13


4.

The total number of orbitals in the fifth energy level is

  • 5

  • 10

  • 18

  • 25


D.

25

The total number of atomic orbitals (total m) in nth shell is equal to n2.

So, in the fifth shell = 52 = 25


5.

A 0.5 g/L solution of glucose is found to be isotonic with a 2.5 g/L solution of an organic compound. What will be the molecular weight of that organic compound ?

  • 300

  • 600

  • 900

  • 200


C.

900

Molarity of glucose solution = 0.5 g180 x 1L = 0.00277 M

Isotonic solution have equal molar concentrations, hence molarity of organic compound solution= 0.00277 M

 Molecular weight of compound = 2.50.00277 × 1 = 900

Therefore, the molecular weight of the given organic compound is 900.


6.

H-O-H bond angle in H2O is 104.5° and not 109° 28' because of

  • lone pair-lone pair repulsion

  • lone pair-bond pair repulsion

  • bond pair-bond pair repulsion

  • high electronegativity of oxygen


A.

lone pair-lone pair repulsion

The hybridisation of oxygen in water molecule is sp3. So, water molecule must be tetrahedral and have bond angle 109°28'. But because of the presence of two lone pair of electrons on oxygen atom (repulsion between lone pair-lone pair) the bond angle decreases about 104.5° and the geometry becomes distorted tertrahedral or V-shaped.


7.

The heat of formation of CO(g) and CO2 (g)are H = -110 and H = - 393 kJ mol-1 respectively. What is the heat of reaction (H) (in kJ mol-1) for the following reaction?

CO (g) + 12O2 (g)  CO2(g)

  • -504

  • -142.5

  • -283

  • 504


C.

-283

C + 12O2  CO, H = -110 kJ mol-1    ...(i)C + O2  CO2  ,  H  = -393 kJ mol-1   ...(ii)On subtracting (i) from (ii), we getCO + 12O2 CO2H = 393 - (-110)         = -283 kJ mol-1


8.

A 0.1 aqueous solution of a weak acid is 2% ionised. If the ionic product of water is 1 x 10-4, the [OH-] is

  • 5 x 10-12 M

  • 2 x 10-3 M

  • 1 x 10-14 M

  • None of these


A.

5 x 10-12 M

Since, it is a weak acid, the equation to calculate [H+] is

 = C x α (α = % of ionisation)

 = 0.1 x 0.02 = 2 x 10-3 M

Kw = [H+][OH-]

[OH-] = Kw[H+] = 1 x 10-142 x 10-3

         = 5 x 10-12 M


9.

Which of the following is correct ?

  • Catalyst undergoes permanent chemical change

  • Particle size of solute in true solution is 10-3 m

  • Starch solution is a hydrosol

  • Hydrolysis of liquid ester in the presence of mineral acid is an example of heterogeneous catalysis reactions


C.

Starch solution is a hydrosol

Starch solution is a hydrosol as it forms colloidal solution with water.


10.

Which of the following is not correct ?

  • Hydrolysis of NCl3 gives NH3 and HOCl

  • NH3 is less stable than PH3

  • NH3 is a weak reducing reagent compared to PH3

  • Nitric oxide in solid state exhibits diamagnetic property


B.

NH3 is less stable than PH3

Among V A group hydrides, the stability decreases in going down the group i.e.,

NH3 > PH3 > AsH3 > SbH3 > BiH3

It is due to the increasing bond length down the group.