Subject

Chemistry

Class

NEET Class 12

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 Multiple Choice QuestionsMultiple Choice Questions

1.

NO2 (brown colour gas) exists in equilibrium with N2O4 (colourless gas) as given by chemical equation.

2NO2(brown)  N2O4(colourless)

Mixture is slightly brown due to existence of NO2. If pressure is increased :

  • colour intensity is increased

  • colour intensity is decreased

  • colour intensity first increases and then decreases

  • No change in colour intensity


2.

ΔHf° (C2H4) , ΔHf° (C2H6) are x1 and x2 kcalmol-1 respectively. Then heat of hydrogenation of C2H4 is :

  • x1 + x2

  • x1 - x2

  • -(x1 - x2)

  • x1 + 2x2


3.

The heat of formation of C12H22O11 (s) , CO2 (g) and (H2O) are - 530 , -94.3 and- 68.3 kcalmol-1 respectively. The amount of C12H22O11 to supply 2700 kcal of energy is :

  • 382.70 g

  • 832.74 g

  • 463.9 g

  • 684.0 g


4.

Spontaneous adsorption of gas on solid surface is an exothermic process because :

  • ΔH increases for system

  • ΔS increases for gas

  • ΔS decreases for gas

  • ΔG increases for gas


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5.

0.1 M solution of CH3COOH should be diluted to how many times so that pH is doubled ?

  • 4.0 times

  • 5.55 x 104 times

  • 5.55 x 106 times

  • 10-2 times


B.

5.55 x 104 times

pH = 12[pKa - log1] = pKa2

pH' (twice of pH) = pKa

pKa12[pKa - logC]

logC = pKa = -logKa

C = Ka = 1.8 x 10-5 M

 Dilution = 1C = 11.8 × 5 = 5.55 x 104 times.


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6.

If the equilibrium constant of the reaction of weak acid HA with strong base is 109 then pH of 0.l M NaA is :

  • 5

  • 9

  • 7

  • 8


7.

For the process ,

X (g) + e-  X- (g) ; ΔH = x

and X- (g)  X (g) + e-ΔH = y

select correct alternate

  • Ionisation energy of x- (g) is y

  • Electron affinity of X (g) is x

  • Electron affinity of X (g) is - y

  • All of the above


8.

Mass of one atom is 6.66 x 10-23 g. Its percentage in an hydride is 95.24. Thus , hydride is :

  • MH

  • MH2

  • MH3

  • MH4


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9.

A 1 L flask contains 32 g O2 gas at 27C. What mass of Omust be released to reduce the pressure in the flask to 12.315 atm?

  • 8 g

  • 16 g

  • 24 g

  • 32 g


10.

1 mol of O2 and x mol of Ne in a 10 L flask at constant temperature exert a pressure of 10 atm. If partial pressure of O2 is 2 atm , moles of Ne in the mixture is :

  • 1

  • 2

  • 4

  • 3


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