Class 12 Chemistry - Chapter Surface Chemistry NCERT Solutions | What modification can you suggest in the

Explain what is observed

(i) When a beam of light is passed through a colloidal sol.

(ii) An electrolyte, NaCl is added to hydrated ferric oxide sol.

(iii) Electric current is passed through a colloidal sol?

Why is adsorption always exothermic?

What do you mean by activity and selectivity of catalysts?

Explain the following terms:

(i) Electrophoresis

(ii) Coagulation

(iii) Dialysis

(iv) Tyndall effect.

What is an adsorption isotherm? Describe Freundlich adsorption isotherm.

Explain the terms with suitable examples:

(i) Alcosol

(ii) Aerosol

(iii) Hydrosol

How are colloids classified on the basis of

(i) Physical states of components

(ii) Nature of dispersion medium and

(iii) Interaction between dispersed phase and dispersion medium?

Discuss the effect of pressure and temperature on the adsorption of gases on solids.

Why does physisorption decrease with the increase of temperature

What are the factors which influence the adsorption of a gas on a solid?

For the reaction R → P, the concentration of a reactant changes from 0.03 M to 0.02 M in 25 minutes. Calculate the average rate of reaction using units of time both in minutes and seconds.

Write the formulas for the following coordination compounds:

(i) Tetraamminediaquacobalt (III) chloride

(ii) Potassium tetracyanonickelate(II)

(iii) Tris(ethane-1,2-diamine) chromium(III) chloride

(iv) Amminebromidochloridonitrito-N-platinate(II)

(v) Dichloridobis(ethane-1,2-diamine)platinum(IV) nitrate

(vi) Iron(III) hexacyanoferrate(II)

(i) Write structures of different isomeric amines corresponding to the molecular formula, C4H11N

(ii) Write IUPAC names of all the isomers.

(iii) What type of isomerism is exhibited by different pairs of amines?

Why are solids rigid?

Write the structures of the following compounds.

(i) α-Methoxypropionaldehyde

(ii) 3-Hydroxybutanal

(iii) 2-Hydroxycyclopentane carbaldehyde

(iv) 4-Oxopentanal

(v) Di-sec-butyl ketone

(vi) 4-Fluoroacetophenone

Which of the ores mentioned in Table 6.1 can be concentrated by magnetic separation method?

Why are pentahalides more covalent than trihalides?

Silver atom has completely filled d orbitals (4d10) in its ground state. How can you say that it is a transition element?

Glucose or sucrose are soluble in water but cyclohexane or benzene (simple six membered ring compounds) are insoluble in water. Explain.

Write structures of the following compounds:

(i) 2-Chloro-3-methylpentane

(ii) 1-Chloro-4-ethylcyclohexane

(iii) 4-tert. Butyl-3-iodoheptane

(iv) 1,4-Dibromobut-2-ene

(v) 1-Bromo-4-sec. butyl-2-methylbenzene

Explain why Cu⁺ ion is not stable in aqueous solutions?

Describe the preparation of potassium permanganate. How does the acidifiedpermanganate solution react with

(i) iron

(II) ions 

(ii) SO₂ and

(iii) oxalic acid?

Write the ionic equations for the reactions.

Gold (atomic radius = 0.144 nm) crystallises in a face-centred unit cell. What is the length of a side of the cell?

Amongst the following ions which one has the highest magnetic moment value?

(i) [Cr(H₂O)₆]³⁺

(ii) [Fe(H₂O)₆]²⁺

(iii) [Zn(H₂O)₆]²⁺

Calculate the 'spin only' magnetic moment of M²⁺_(aq) ion (Z = 27).

The time required for 10% completion of a first order reaction at 298 K is equal to that required for its 25% completion at 308 K. If the value of A is 4 x 10¹⁰ s^-1. Calculate k at 318 K and E_a.

Why are pentahalides more covalent than trihalides?

100 g of liquid A (molar mass 140 g mol^-1) was dissolved in 1000 g of liquid B (molar mass 180 g mol^-1). The vapour pressure of pure liquid B was found to be 500 torr. Calculate the vapour pressure of pure liquid A and its vapour pressure in the solution if the total vapour pressure of the solution is 475 Torr.

How is SO₂ an air pollutant?

Give reason for the higher boiling point of ethanol in comparison to methoxymethane.