pKa increases in benzoic acid when substituent "x" is bonded at p

Subject

Chemistry

Class

NEET Class 12

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 Multiple Choice QuestionsMultiple Choice Questions

1.

Threshold frequency of a metal is 5 × 1013 s-1 upon which 1 x 1014s-1 frequency light is focused. Then the maximum kinetic energy of emitted electron is

  • 3.3 × 10-21

  • 3.3 × 10-20

  • 6.6 × 10-23

  • 6.6 × 10-20


2.

At equilibrium which is correct?

  • G = 0

  • S = 0

  • H = 0

  •  G°= 0


3.

Arrange the following gases in order of their critical temperature.
NH3, H2O, CO2, O2

  • NH> H2O > CO> O2

  • O> CO> H2O > NH3

  • H2O > NH> CO> O2

  • CO>O>H2O > NH3


4.

Bond dissociation energy of CH4 is 360 kJ/mol and C2His 620 kJ/mol. Then bond dissociation energy of C-C bond is

  • 170 kJ/mol

  • 50 kJ/mol

  • 80 kJ/mol

  • 220 kJ/mol


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5.

In Bohr's Orbit, nh2π indicates

  • Momentum

  • Kinetic energy

  • Potential energy

  • Angular momentum


6.

Which has the highest pH?

  • CH3COOK

  • Na2CO3

  • NH4Cl

  • NaNO3


7.

KpKc for following reaction will be CO(g)+12 O2(g)CO2(g).

  • RT

  • 1RT

  • 1RT

  • RT2


8.

The dipole moment is minimum in

  • NH3

  • NF3

  • SO2

  • BF3


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9.

At 60° and 1 atm, N2O4 is 50% dissociated into NO2 then KP is

  • 1.33 atm

  • 2 atm

  • 2.67 atm

  • 3 atm


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10.

pKa increases in benzoic acid when substituent "x" is bonded at para-position, then "x" is

  • -COOH

  • -NO2

  • -CN

  • -OCH3


D.

-OCH3

Larger the value of pKa smaller will be its acidity. Out of the four groups, -COOH, -NO2 and -CN are e- withdrawing which makes benzoic acid more acidic whereas -OCH3 is e- donating which reduces the acidity (makes H less easily available). pKa value increases if OCH3 is present at para-position of benzoic acid.


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