Which of the following is only acidic nature? from Chemistr

Subject

Chemistry

Class

NEET Class 12

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 Multiple Choice QuestionsMultiple Choice Questions

11.

What is the pH of 0.01 M glycine solution? For glycine Ka1 = 4.5 ×10-3 and Ka2 = 1.7 ×10-10  at  298K?

  • 3

  • 10

  • 6.1

  • 7.2


12.

Of the following which change will shift the reaction towards the product?

I2(g) 2I(g), Hf° (298K) = +150kJ

  • Increase in concentration of I

  • Decrease in concentration of I2

  • Increase in temperature

  • Increase in total pressure


13.

Assertion : The free gaseous Cr atom has six unpaired electrons.

Reason: Half-filled s orbital has greater stability.

  • 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.


14.

Assertion : Nuclear binding energy per nucleon is in the order - Be49 >Li37 >He24

Reason : Binding energy per nucleon increases linearly with difference in number of neutrons and protons.

  • 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.


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15.

Assertion : All F- S -F angle in SF4 is greater than 90° but less than 180°.

Reason : The lone pair-bond pair repulsion is weaker than bond pair-bond pair repulsion.

  • 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.


16.

Assertion : Effusion rate of oxygen is smaller than nitrogen.

Reason: Molar mass of nitrogen is smaller than oxygen.

  • 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.


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17.

Which of the following is only acidic nature?

  • Be(OH)2

  • Mg(OH)2

  • B(OH)3

  • Al(OH)3


C.

B(OH)3

B(OH)3 in aqueous medium coordinates a molecule of water to form the hydrated species     OH/HB(OH)3. In this species, B3+ ion, because of its small size, exercises a high polarizing power thereby pulling the sigma electron charge of the coordinated O atom towards itself. The coordinated oxygen, in turn, pulls the sigma electron charge of the OH bond of the attached H2O molecule towards itself. This facilitates the removal of H+ ion from the O- H bond, as shown below.

OH /H B(OH)3  [B(OH)4]- + H+

Thus the solution of B(OH)3 in water acts as a weak acid. That is why it reacts with NaOH solution to produce the sodium salt.

B(OH)3 + NaOH  Na+[ B(OH)4]-Na+BO2-sodium metaborate+ 2H2O


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18.

Which of the following imparts green colour to the burner flame?

  • B(OMe)3

  • Na(OMe)

  • Al(OPr)3

  • Sn(OH)2


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19.

The strongest base among the following is


20.

The compound having only primary hydrogen atoms is

  • isobutene

  • 2,3-dimethylbutene

  • cyclohexane

  • propyne


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