The addition of a catalyst during a chemical reaction alters which of the following quantities ?

• Internal energy

• Enthalpy

• Activation energy

• Activation energy

Predict the correct order among the following.

• long pair-lone pair> bond pair-bond pair> lone pair>bond pair

• bond pair-bond pair> lone pair-bond pair > lone pair -lone pair

• lone pair -bond pair > bond pair- bond pair> lone pair -lone pair

• lone pair -bond pair > bond pair- bond pair> lone pair -lone pair

Two electrons occupying the same orbital are distinguished by

• Magnetic quantum number

• Azimuthal quantum number

• Spin quantum number

• Spin quantum number

The electronic configuration of Eu (Atomic no.63), Gd (Atomic no. 64) and Tb (Atomic no. 65) are

• [Xe]4f⁶ 5d¹ 6s², [Xe] 4f⁷ 5d¹ 6s² and [Xe] 4f⁹  6s² 

• [Xe] 4f⁶ 5d¹ 6s² , [Xe] 4f⁷ 5d¹ 6s² and [Xe] 4f⁸ 5d¹ 6s² 

• [Xe] 4f⁷  6s², [Xe] 4f⁷ 5d¹ 6s² and [Xe] 4f⁹ 6s² 

• [Xe] 4f⁷  6s², [Xe] 4f⁷ 5d¹ 6s² and [Xe] 4f⁹ 6s² 

Which one of the following characteristics is associated with adsorption?

• ΔG, ΔH and  ΔS all are negative

• ΔG and  ΔH are negative but  ΔS is positive

• ΔG and  ΔS are negative but  ΔH is positive

• ΔG and  ΔS are negative but  ΔH is positive

The pair of an electron in the given carbanion, is present in which orbital? 

• sp³

• sp²

• sp

• sp

Consider the molecules CH₄, NH₃ and H₂O. Which of the given statement is false?

• The H-O-H bond angle in H₂O  is larger than the H-C-H bond angle in CH₄.

• The H-O-H bond angle in H₂O is smaller than the H-N-H bond angle in NH₃.

• The H-C-H bond angle in CH₄ is larger than the H-N-H bond angle in NH₃

• The H-C-H bond angle in CH₄ is larger than the H-N-H bond angle in NH₃

The correct thermodynamic conditions for  the spontaneous reaction at all temperatures is

• ΔH> 0 and Δ S< 0
• ΔH< 0 and ΔS > 0
• ΔH ΔS >0
• ΔH ΔS >0

In which of the following options the order of arrangement does not agree with the variation of the property indicated against it?

• B<C<N<O (increasing first ionisation enthalpy)

• I<Br<Cl<F(increasing electron gain enthalpy)

• Li<Na<K<Rb (increasing metallic radius)

• Li<Na<K<Rb (increasing metallic radius)

Equal moles of hydrogen and oxygen gases are placed in a container with a pin-hole through which both can escape. What fraction of the oxygen escapes in the time required for one-half of the hydrogen to escape?

• 1/4

• 3/8

• 1/2

• 1/2