Science (English Medium) इयत्ता १२ - CBSE Important Questions

What causes actinoid contraction?

What is the oxidation state of chromium in chromate ion and dichromate ion?

Write the ionic equation for reaction of KI with acidified KMnO₄.

Write the dispersed phase and dispersion medium of the following colloidal systems: 

(i) Smoke

(ii) Milk

What are lyophilic and lyophobic colloids ? Which of these sols can be easily coagulated on the addition of small amounts of electrolytes?

What are lyophilic and lyophobic colloids ? Which of these sols can be easily coagulated on the addition of small amounts of electrolytes?

Write the differences between physisorption and chemisorption with respect to the following: 

(i) Specificity

(ii) Temperature dependence

(iii) Reversibility and

(iv) Enthalpy change

The complex ion `[Co(H_2O)_5 (ONO)]^(2+) `

(A) linkage isomer

(B) ionisation isomer

(C) co-ordination isomer

(D) geometrical isomer

For the complex [Fe(H₂O)₆]+3, write the hybridisation, magnetic character and spin of the complex. (At, number : Fe = 26)

Draw one of the geometrical isomers of the complex [Pt (en)₂Cl₂] ⁺² which is optically inactive

Define the following terms: Lyophilic colloid

Define the following terms: Lyophilic colloid

Define the following terms: Associated colloids

Write a method by which lyophobic colloids can be coagulated.

Write a method by which lyophobic colloids can be coagulated.

Give reasons for the following observations:

Physisorption decreases with increase in temperature.

Give reasons for the following observations: Addition of alum purifies the water

Give reasons for the following observations:

Brownian movement provides stability to the colloidal solution.

On the basis of crystal field theory, write the electronic configuration for d⁴ ion if Δ₀ > P.

What is the effect of temperature on chemisorption ?