JEE Advanced (Single Correct MCQs): The Solid State & Surface Chemistry - JEE MCQ

For bcc structure, atomic radius, 

Since, r = half the distance between two nearest
neighbouring atoms.
∴ Shortest inter ionic distance = 2 × 1.86 = 3.72

In a hcp structure atoms are located at the corners and at centres of two hexagons placed parallel to each other ; three more atoms are placed in a parallel plane midway between these two planes. Here each atom is surrounded by 12 others and is said to have
co-ordination number of 12.

(d) Effective number of ‘A’ atoms = 

Effective number of ‘B’ atoms = 

∴ Formula of the solid = A₃B₄.

Effective number of atoms at corners, 

Effective number of atoms at centre,

Thus, the composition will be AB₃

Rate of physiorsption increases with decrease of temperature

 = amt of gas adsorbed per unit
mass of adsorbent

t = temperature

When a gas is adsorbed on the surface, the freedom of movement of its molecules becomes restricted. This causes decrease in the entropy of the gas after adsorbtion, i.e. ΔS becomes negative

In ZnS structure, sulphide ions occupy all FCC lattice points while Zn²⁺ ions are present in alternate tetrahedral voids.

Lyophilic sols are self stabilizing because these sols are reversible and are highly hydrated in the solution.

We know that surface acting agents (i.e. surfactants) such as soaps and detergents belong to the class of micelles. A miceller system when dissolved in water, dissociates to give ions. The anion consists of two parts. The polar groups such as ion
is water loving (i.e. hydrophilic) in nature. It is called head of the species. The hydrocarbon chain which is quite big in size is water repelling (i.e. hydrophobic) in nature. It is called tail of the species. The hydrocarbon
chain aggregates into the micelle above the critical concentration.
NOTE : It may also be noted that the critical
concentration for micelle formation decreases with increase in the molecular weight of the hydrocarbon chain of surfactant.
Here the two anions that are formed are in case of "B"

The molecular weight of hydrocarbon chain is more in case of "B" so it has lower value of critical concentration for micelle formation in aqueous solution.
Hence the correct answer is option (b).

As Sb₂S₃ is a negative sol, so Al₂(SO₄)₃ will be the most effective coagulant due to higher positive charge on Al (Al³⁺) – Hardy-Schulze rule.

No. of M atoms = 

No. of X atoms = 

So, formula = M₂X₄ = MX₂

The arrangement given shows octahedral void
arrangement-limiting radius ratio for octahedral void is

The adsorption of methylene blue on activated charcoal is an example of physiosorption which is exothermic, multilayer and does not have energy barrier.