Subject

Chemistry

Class

NEET Class 12

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 Multiple Choice QuestionsMultiple Choice Questions

11.

Which of the following hydrocarbons is the most reactive towards addition of H2SO4?

  • Ethene

  • Propylene

  • 3-methyl but-1-ene

  • 1-butene


C.

3-methyl but-1-ene

As π-bond is more activated, the addition of H2SO4 is carried out lastly. In the given compound, 3-methyl but-1-ene undergoes rapid addition, because π-bond is activated by hyperconjugation and after addition the most stable 3°-carbocation is formed.


12.

Consider the following structures

Choose the correct statement regarding the above structures.

  • Dipole moment varies as II > III > I

  • II is more stable than I

  • I is the most reactive among three

  • All of the above


D.

All of the above

Hence, dipole moment decreases as II > III > I

Stability can be represented as II > III > I

Reactivity can be represented as III > II > I.


13.

100 mL of a solution contains 2 g of acetic acid and 3g of sodium acetate providing Ka =1.8 x 10-5 , then choose the correct option.

  • This solution is basic in nature

  • This solution is acidic in nature

  • This solution is amphoteric in nature

  • This solution is neutral in nature


B.

This solution is acidic in nature

pH formula is,

pH = - log Ka + log[Salt][Base]

[Salt] = 3 × 100082 ×100  mol L-1[Acid] = 2 × 100060 × 100 mol L-1

pH = - log 1.8 × 10-5 + log 3 × 100082 × 1002 × 100060 × 100

pH = 4.7851


14.

Match the particle with its characteristic

Column I Column II
A. α-particle p. Slow moving
B. Isobar q. High penetration power
C. γ- ray r. Same atomic mass
D. β- particle s. consists of electron

  • A - p; B - r; C - q; D - s

  • A - p; B - q; C - r; D - s

  • A - r; B - s; C - p; D - q

  • A - s; B - r; C - p; D - q


A.

A - p; B - r; C - q; D - s

Column I Column II
A. α- particle p. Slow moving
B. Isobar r. Same atomic mass
C. γ- ray q. High penetration power
D. β- particle s. Consists of electron

15.

At radioactive equilibrium, the ratio between two atoms of radioactive elements A and B is 3.1 x 109 : 1. If the half-life period of A is 2 x 1010 yrs, then the half-life of B is

  • 9.54 yrs

  • 2.14 yrs

  • 3.29 yrs

  • 6.45 yrs


D.

6.45 yrs

Ratio of A : B = 3.1 x 109 : 1

Half life of A = 2 x 1010 yrs.

Half life of B is = 

AB = 3.1 × 1091If x is the half life period of B, then,  3.1 × 1091  = 2 × 1010x x = 2 × 10103.1 ×109 = 0.645 ×101 = 6.45 yrs.


16.

11.2 L of gas at STP Weight 14g. The gas would be

  • H2

  • CO

  • B2H6

  • All of these


D.

All of these

Molecular weigth of gas = 14 × 22.411.2 = 28

The above formula denotes the formula of mole concept. The gas would be CO, N2, B2H6.


17.

When 2-methyl butyl bromide is treated with sodium ethoxide in ethanol, what will be the major product?

  • 2-methyl but-2-ene

  • 3-methyl but-1-ene

  • 2-methyl but-1-ene

  • 2-methyl sodium-butoxide


A.

2-methyl but-2-ene

When 2-methyl butyl bromide is treated with sodium ethoxide in ethanol, two alkenes are possible. The more substituted alkene, i.e. 2-methyl-2-butene is the major product.


18.

Highest energy will be absorbed to eject out the electron in the configuration.

  • 1s22s22p1

  • 1s22s22p3

  • 1s22s22p2

  • 1s22s22p4


B.

1s22s22p3

Highest electric will be absorbed to eject out the electron in the configuration of 1s22s22p3


19.

For the formation of Cr2O3 and Al2O3, values of fG° are 540 kJ mol-1 and -827 kJ mol-1 respectively. What will be the possibility for reaction of Cr2O3 by Al?

  • Reduction of Cr2O3 by Al will take place

  • Oxidation of Cr2O3 by Al will take place

  • Neither oxidation nor reduction will take place

  • Reaction is not feasible


A.

Reduction of Cr2O3 by Al will take place

2Cr + 32 O2 Cr2O3 ; G° = -540 kJ mol-1 ..... (i)2Al + 32 O2  Al2O3; G° = -827 kJ mol-1 ..... (ii)

On substrating equation (i) from (ii)

2Al + Cr2O3 Al2O3 + 2Cr

rG = [-827 - (-540)] kJ mol-1

       = -287 kJ mol-1 

G°  value is negative for the reduction by Al. Therefore, the reaction is feasible.


20.

Both Mg and Fe metal can reduce copper from a solution having Cu2+ ion, according to equilibria.

Mg(s) + Cu2+  Mg2+ + Cu(s); K1 = 6 x 1090

Fe(s) + Cu2+  Fe2+ + Cu(s); K2 = 3 x 1026

Choose the correct option regarding above equilibrium

  • Mg removes more Cu2+ from solution

  • Fe removes more Cu2+ from solution

  • Both will equally remove Cu2+ from solution

  • Both metals cannot remove Cu2+ from solution


A.

Mg removes more Cu2+ from solution

Since, K1 > K2, the product in the first reaction is much more favoured than in the second one. Mg thus removes more Cu2+ from solution than Fe does.