In the lime kiln, the reaction CaCO₃(s) → CaO(s) + CO₂ (g) goes to completion because:

• of high temperature

• CaO is more stable than CaCO₃

• CO₂ escapes simultaneously

• CO₂ is a gaseous product

The rate of a reaction is doubled for every 10° rise in temperature. The increase in reaction rate as a result of temperature rise from 10° to 100° is :

• 112

• 512

• 400

• 614

When a beam of light is passed through a colloidal solution it :

• is reflected

• is scattered

• transmitted

• absorbed

The electron affinity values for the halogens show the following trend :

• F < Cl > Br >I

• F < Cl< Br< I

• F > Cl > Br > I 

• F < Cl > Br < I

When H₂S gas is passed through nitric acid, the product is:

• prismatic S (colloidal)

• amorphous S

• monoclinic S

• plastic S

Atoms in a P₄ molecule of white phosphorus are arranged regularly in space in which of the following way ?

• At the comers of tetrahedron

• At the comers of a cube

• At the comers of a four membered ring

• At the centre and comers of a equivalent triangle

The catalytic activity of the transition metals and their compounds is described to :

• their chemical reactivity 

• their magnetic behaviour

• their unfilled d-orbitals

• their ability to adopt multiple oxidation states and their complexing ability

28.

The compound ZnFe₂O₄ is:

• a normal spinel compound

• a inverse spinel compound

• interstitial compound

• covalent compound

High purity Si and Ge for semiconductor properties can be obtained by :

• calcination

• roasting

• zone refining

• thermic process

Name of the alloy of aluminium which is used in aeroplane is :

• duralumin

• bell metal

• aluminium bronze

• alumina