Science (English Medium) कक्षा १२ - CBSE Question Bank Solutions for Chemistry

Account for the following: Reducing character increases from NH₃ to BiH₃.

For a reaction : 

(i) Write the order and molecularity of this reaction.

(ii) Write the unit of k.

In the extraction of Al, impure Al₂O₃ is dissolved in conc. NaOH to form sodium aluminate and leaving impurities behind. What is the name of this process?

What is the role of coke in the extraction of iron from its oxides?

Arrange the following in the increasing order of property mentioned :

H₃PO₃, H₃PO₄, H₃PO₂ (Reducing character)

How can you distinguish between propanal and propanone?

Indicate the principle behind the method used for the refining of zinc.

What is the role of silica in the extraction of copper?

Which form of the iron is the purest form of commercial iron?

For the hydrolysis of methyl acetate in aqueous solution, the following results were obtained :

(i) Show that it follows pseudo first order reaction, as the concentration of water remains constant.

(ii) Calculate the average rate of reaction between the time interval 30 to 60 seconds.

(Given log 2 = 0.3010, log 4 = 0.6021)

For a chemical reaction R → P, the variation in the concentration (R) vs. time (t) plot is given as:

(i) Predict the order of the reaction.

(ii) What is the slope of the curve ?

(iii) Write the unit of rate constant for this reaction.

The following data were obtained during the first order thermal decomposition of SO₂Cl₂ at a constant volume :

SO₂Cl₂ (g) → SO₂ (g) + Cl₂ (g)

Calculate the rate constant.

(Given : log 4 = 0.6021, log 2 = 0.3010)

Give reasons for the following : (CH₃)₃ P = O exists but (CH₃)₃ N = O does not.

Describe the roles of the following: SiO₂ in the extraction of copper from copper matte

Name the method used for refining of copper metal.

Classify the following solids in different categories based on the nature of intermolecular forces operating in them:

Potassium sulphate, tin, benzene, urea, ammonia, water, zinc sulphide, graphite, rubidium, argon, silicon carbide.

Classify each of the following solids as ionic, metallic, molecular, network (covalent) or amorphous.

(i) Tetra phosphorus decoxide (P₄O₁₀) 

(ii) Ammonium phosphate (NH₄)₃PO₄ 

(iii) SiC 

(iv) I₂ 

(v) P₄ 

(vii) Graphite

(viii) Brass

(ix) Rb

(x) LiBr

(xi) Si

Define the term solution.

For a reaction, \[\ce{A + B -> Product}\]; the rate law is given by, `r = k[A]^(1/2)[B]^2`. What is the order of the reaction?

The conversion of molecules X to Y follows second order kinetics. If concentration of X is increased to three times how will it affect the rate of formation of Y?