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 Multiple Choice QuestionsMultiple Choice Questions

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11.

The half life period of a first order chemical reaction is 6.93 minutes. The time required for the completion of 99% of the chemical reaction will be (log 2=0.301) 

  • 230.3 minutes

  • 23.03 minutes

  • 46.06 minutes

  • 46.06 minutes

226 Views

12.

Solid Ba (NO3)2 is gradually dissolved in a 1.0x 10−4 × Na2CO3 solution. At what concentration of Ba2+ will a precipitate begin to form?(Ksp for BaCO3 = 5.1 ×10−9  )

  • 4.1 x 10-5 M

  • 5.1 x 10-5 M

  • 8.1 x 10-8 M

  • 8.1 x 10-8 M

1102 Views

13.

For a reaction 1/2A →2B, rate of disappearance of ‘A’ is related to the rate of appearance of ‘B’ by the expression

  • negative fraction numerator straight d left square bracket straight A right square bracket over denominator dt end fraction space equals space 1 half fraction numerator straight d left square bracket straight B right square bracket over denominator dt end fraction
  • negative fraction numerator straight d left square bracket straight A right square bracket over denominator dt end fraction space equals space 1 fourth fraction numerator straight d left square bracket straight B right square bracket over denominator dt end fraction
  • negative fraction numerator straight d left square bracket straight A right square bracket over denominator dt end fraction space equals space fraction numerator straight d left square bracket straight B right square bracket over denominator dt end fraction
  • negative fraction numerator straight d left square bracket straight A right square bracket over denominator dt end fraction space equals space fraction numerator straight d left square bracket straight B right square bracket over denominator dt end fraction
251 Views

14.

The energies of activation for forward and reverse reactions for A2 + B2 ⇌ 2AB are 180 kJ mol–1 and 200 kJ mol–1 respectively. The presence of a catalyst lowers the activation energy of both (forward and reverse) reactions by 100 kJ mol–1. The enthalpy change of the reaction (A2 + B2 → 2AB) in the
presence of catalyst will be (in kJ mol–1) –

  • 300

  • 120

  • 280

  • 280

916 Views

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15.

Consider the reaction, 2A + B → Products. When the concentration of B alone was doubled, the half-life did not change. When the concentration of An alone was doubled, the rate increased by two times. The unit of rate constant for this reaction is –

  • L mol–1 s–1

  • no unit

  • mol L–1s–1

  • mol L–1s–1

501 Views

16.

A radioactive element gets spilled over the floor of a room. Its half-life period is 30 days. If the initial activity is ten times the permissible value, after how many days will it be safe to enter the room ?

  • 1000 days

  • 300 days

  • 50 days

  • 50 days

172 Views

17.

Which of the following nuclear reactions will generate an isotope?

  • neutron particle emission

  • positron emission

  • α-particle emission

  • α-particle emission

203 Views

18.

A reaction was found to be second order with respect to the concentration of carbon monoxide. If the concentration of carbon monoxide is doubled, with everything else kept the same, the rate of reaction will

  • remain unchanged

  • triple

  • increase by a factor of 4

  • increase by a factor of 4

133 Views

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19.

In the transformation of straight U presubscript 92 presuperscript 238 space to space straight U presubscript 92 presuperscript 234 , if one emission is an α-particle, what should be the other emission(s)?

  • Two β

  • Two β and one β+

  • One β and one γ

  • One β and one γ

113 Views

20.

In Langmuir’s model of adsorption of a gas on a solid surface

  • the rate of dissociation of adsorbed molecules from the surface does not depend on the surface covered

  • the adsorption at a single site on the surface may involve multiple molecules at the same time

  • the mass of gas striking a given area of the surface is proportional to the pressure of the gas

  • the mass of gas striking a given area of the surface is proportional to the pressure of the gas

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