Subject

Chemistry

Class

NEET Class 12

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 Multiple Choice QuestionsMultiple Choice Questions

11.

25 mL, 0.2 M Ca(OH)2 is neutralised by 10 mL of 1 M HCI. Then pH of resulting solution is

  • 1.37

  • 9

  • 12

  • 7


D.

7

Number of millimoles of Ca(OH)2 = N1V1 = 2 × N1 × V1 = 2 × 0.2 × 25 = 10

Number of millimoles of HCl = N2V2 = 10 × 1 = 10

As, no. of millimoles of Ca(OH)2 = no. of millimoles of base

 Acid is completely neutralised by base forming a neutral solution.

Therefore, pH of the resulting solution is 7. 


12.

Assertion : AgCl is more soluble in NH3 than in water.

Reason : Ammonia is more polar than water.

  • If both assertion and reason are true and reason is the correct explanation of assertion

  • If both assertion and reason are true but reason is not the correct explanation of assertion

  • If assertion is true but reason is false

  • If both assertion and reason are false


C.

If assertion is true but reason is false

Solubility of AgCl (at 25°C) in H2O = 0.0020 gm AgCl per litre of H2O

Solubility of AgCl in NH3 (at 25°C) = 14.00 gm AgCl dissolved per kg of NH3

Ammonia is less polar than water, as oxygen is more electronegative than nitrogen.


13.

For a first order gas phase reaction-

A(g)  2B(g) + C(g)

P0 be initial pressure of A and P, the total pressure at time 't'. Integrated rate equation is

  • 2.303tlogP0P0 - Pt

  • 2.303tlog2P03P0 - Pt

  • 2.303tlogP02P0 - Pt

  • 2.303tlog2P02P0 - Pt


B.

2.303tlog2P03P0 - Pt

Initial  A(g)P0P0-P  2B(g)02P + C(g)0P

Total pressure at time (t) = P0 - P + 2P + P = Pt

 Pt = P0 + 2P

 Pt - P0 = 2P

 P = Pt - P02 

k = 2.303tlogP0P0 - P = 2.303tlogP0P0 - Pt - P02= 2.303tlog2P02P0 - Pt + P0= 2.303tlog2P03P0 - Pt


14.

Assertion : R3P=O exists but R3N=O does not exist.

Reason : P is more electronegative than N.

  • If both assertion and reason are true and reason is the correct explanation of assertion

  • If both assertion and reason are true but reason is not the correct explanation of assertion

  • If assertion is true but reason is false

  • If both assertion and reason are false.


C.

If assertion is true but reason is false

R3P=O exists but R3N=O does not exist, this is because electronegativity of N (3.0) is much higher than P (2.1).


15.

Which of the following is intensive property?

  • Enthalpy

  • Entropy

  • Specific heat

  • Volume


C.

Specific heat

Intensive property in thermodynamics is independent of the amount of mass. Specific heat is an intensive property.

Extensive property in thermodynamics varies directly with mass. It includes enthalpy, entropy and volume.


16.

The number of σ- and π-bonds present in pent-4-ene-1-yne is

  • 10, 3

  • 4, 9

  • 3, 10

  • 9, 4


A.

10, 3

Pent-4-ene-1-yne

C1HC2-C3H2-C4H=C5H2

No. of σ bonds - 4 (C - C) + 6 (C - H) = 10

No. of π bonds - 1 (C = C) + 2 (C  C) = 3


17.

Assertion : H2S is less acidic than H2Te.

Reason : Te has larger, radius than S.

  • If both assertion and reason are true and reason is the correct explanation of assertion

  • If both assertion and reason are true but reason is not the correct explanation of assertion

  • If assertion is true but reason is false

  • If both assertion and reason are false.


B.

If both assertion and reason are true but reason is not the correct explanation of assertion

H2S is less acidic than H2Te because as the size of the atom S in H2S increases, the strength of the H - M bond decreases.


18.

Assertion : A reaction is spontaneous if Ecell = +ve.

Reason : For Ecell = +ve, G is always -ve.

  • If both assertion and reason are true and reason is the correct explanation of assertion

  • If both assertion and reason are true but reason is not the correct explanation of assertion

  • If assertion is true but reason is false

  • If both assertion and reason are false


A.

If both assertion and reason are true and reason is the correct explanation of assertion

For a redox reaction to be spontaneous, the EMF of the cell must be positive.

As, -G = nFEcell

Therefore, for Ecell = +ve, G is always negative.


19.

Which of the following is not a thermodynamic function?

  • Internal energy

  • Work done

  • Enthalpy

  • Entropy


B.

Work done

Thermodynamic functions include internal energy whose change can be expressed in terms of heat and work; enthalpy, entropy, pressure, volume, temperature, free energy, number of moles.


20.

Assertion : Helium is used in diving apparatus.

Reason : Solubility of helium is less in blood.

  • If both assertion and reason are true and reason is the correct explanation of assertion

  • If both assertion and reason are true but reason is not the correct explanation of assertion

  • If assertion is true but reason is false

  • If both assertion and reason are false.


A.

If both assertion and reason are true and reason is the correct explanation of assertion

A mixture of 2% O2 and 98% He is used in diving apparatus which gives the same partial pressure of O2 as in normal air at 1 atm. Due to high partial pressure and greater solubility, N2 gets dissolved in blood and form bubbles (bends or decompression sickness). Hence, Nis replaced by helium which is much less soluble in biological fluids.