21.

Which of the following does not result in an increase in entropy?

• Crystallisation of sucrose form a solution

• Rusting of iron

• Conversion of ice ofwater

• Vaporisation of camphor

For which of the following species, Bohr theory does not apply?

• H

• He⁺

• H⁺

• Li²⁺

In the modern periodic table the place of the element with atomic number 31 is in

• s- block

• d-block

• p- block

• f- block

Which of the following does not exhibit the periodicity in properties of the elements?

• Ionisation energy

• n/p ratio

• Electronegativity

• Atomic radius

The correct sequence of decrease in size of the following species is

• I> I⁺> I^-

• I> I^-> I⁺

• I⁺> I^-> I

• I^-> I> I⁺

The decreasing order of the ionisation potential in the following elements is

• Ne> Cl>P> S>Al>Mg

• Ne> Cl> P> S> Mg> Al

• Ne> Cl> S>P> Mg> Al

• Ne> Cl> S>P> Al> Mg

Which of the following represents the electronic configuration of the most electropositive element?

• [He]2s¹

• [He]2s²

• [Xe]6s¹

• [Xe]2s²

Which of the following reactions is a redox reaction?

• 2AgNO₃ + BaCl₂ → 2AgCl + Ba(NO₃)₂

• BaO₂ + H₂SO₄  → BaSO₄ + H₂O₂

• P₂O₅ + 2H₂O  → H₄P₂O₇

• Cu + 2AgNO₃  → 2Ag + Cu(NO₃)₂

In the reaction 2Fe³⁺(aq) + Sn²⁺(aq) → 2Fe²⁺(aq) + A

A belongs to

• Sn⁴⁺(aq)

• Sn²⁺(aq)

• Sn³⁺(aq)

• Sn⁰

Which one of the following is an s-block element?

• Aluminium

• Chromium

• Niobium

• Potassium