Science (English Medium) Class 12 - CBSE Question Bank Solutions for Chemistry

In physisorption adsorbent does not show specificity for any particular gas because ______.

In which of the following reactions heterogenous catalysis is involved?

(a) \[\ce{2SO2 (g) + O2 (g) ->[NO(g)] 2SO3 (g)}\]

(b) \[\ce{2SO2 (g) ->[Pt(s)] 2SO3 (g)}\]

(c) \[\ce{N2 (g) + 3H2 (g) ->[Fe(s)] 2NH3 (g)}\]

(d) \[\ce{CH3COOCH3 (l) + H2O (l) ->[HCI(l)] CH3COOH (aq) + CH3OH (aq)}\]

Why is it important to have clean surface in surface studies?

Why is chemisorption referred to as activated adsorption?

Why do physisorption and chemisorption behave differently with rise in temperature?

What is the role of activated charcoal in gas mask used in coal mines?

Give an example where physisorption changes to chemisorption with rise in temperature. Explain the reason for change.

What is the role of diffusion in heterogenous catalysis?

Assertion: Detergents with low CMC are more economical to use.

Reason: Cleansing action of detergents involves the formation of micelles. These are formed when the concentration of detergents becomes equal to CMC.

What is the role of adsorption in heterogenous catalysis?

Which of the following elements can be involved in pπ – dπ bonding?

On heating lead nitrate forms oxides of nitrogen and lead. The oxides formed are ______.

Name three oxoacids of nitrogen. Write the disproportionation reaction of that oxoacid of nitrogen in which nitrogen is in +3 oxidation state.

Assertion: \[\ce{HNO3}\] makes iron passive.

Reason: \[\ce{HNO3}\] forms a protective layer of ferric nitrate on the surface of iron.

On heating lead (II) nitrate gives a brown gas “A”. The gas “A” on cooling changes to colourless solid “B”. Solid “B” on heating with NO changes to a blue solid ‘C’. Identify ‘A’, ‘B’ and ‘C’ and also write reactions involved and draw the structures of ‘B’ and ‘C’.

Electronic configuration of a transition element X in +3 oxidation state is [Ar]3d⁵. What is its atomic number?

Metallic radii of some transition elements are given below. Which of these elements will have highest density?

Generally transition elements form coloured salts due to the presence of unpaired electrons. Which of the following compounds will be coloured in solid-state?

The magnetic nature of elements depends on the presence of unpaired electrons. Identify the configuration of transition element, which shows highest magnetic moment.

When \[\ce{KMnO4}\] solution is added to oxalic acid solution, the decolourisation is slow in the beginning but becomes instantaneous after some time because ______.