PUC Science 2nd PUC Class 12 - Karnataka Board PUC Question Bank Solutions for Chemistry

Why does NH₃ form hydrogen bond but PH₃ does not?

The HNH angle value is higher than HPH, HAsH and HSbH angles. Why? [Hint: Can be explained on the basis of sp³ hybridisation in NH₃ and only s−p bonding between hydrogen and other elements of the group].

Justify the placement of O, S, Se, Te and Po in the same group of the periodic table in terms of electronic configuration, oxidation state and hydride formation.

Knowing the electron gain enthalpy values for \[\ce{O -> O-}\] and \[\ce{O -> O^{2-}}\] as −141 and 702 kJ mol⁻¹ respectively, how can you account for the formation of a large number of oxides having O²⁻ species and not O⁻?

(Hint: Consider lattice energy factor in the formation of compounds).

Why are halogens strong oxidising agents?

Explain why inspite of nearly the same electronegativity, oxygen forms hydrogen bonding while chlorine does not.

Give reasons:

The dipole moment of chlorobenzene is lower than that of cyclohexyl chloride.

Arrange the following in the order of property indicated for the given set:

F₂, Cl₂, Br₂, I₂ - increasing bond dissociation enthalpy.

State second law of electrolysis

Suggest the most important type of intermolecular attractive interaction in the following pair.

n-hexane and n-octane

Suggest the most important type of intermolecular attractive interaction in the following pair:

I₂ and CCl₄

Suggest the most important type of intermolecular attractive interaction in the following pair.

NaClO₄ and water

Suggest the most important type of intermolecular attractive interaction in the following pair.

Methanol and acetone

Silver crystallises in FCC structure. If density of silver is 10.51 gcm^-3, calculate the volume of unit cell. [Atomic mass of slive (Ag) = 108 gm^-1]

Name the method used for the refining of Nickel metal.

Explain the mechanism of the following reaction:

Give one example each for fibrous protein and globular protein.

For the complex [Fe(H₂O)₆]+3, write the hybridisation, magnetic character and spin of the complex. (At, number : Fe = 26)

Give reasons for the following:

Aniline does not undergo Friedel- Crafts reaction.

An element with density 10 g cm⁻³ forms a cubic unit cell with edge length of 3 × 10⁻⁸ cm. What is the nature of the cubic unit cell if the atomic mass of the element is 81 g mol⁻¹?