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

How do you convert Chlorobenzene to biphenyl?

What is the role of cryolite in the extraction of aluminium?

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

Nitrogen does not form pentahalide.

For the first order thermal decomposition reaction, the following data were obtained:

Time / sec               Totalpressure / atm

0                              0.30

300                          0.50

Calculate the rate constant

(Given: log 2 = 0.301, log3 = 0.4771, log 4 = 0.6021)

Due to hectic and busy schedule, Mr Angad made his life full of tensions and anxiety. He started taking sleeping pills to overcome the depression without consulting the doctor. Mr Deepak, a close friend of Mr. Angad advised him to stop taking sleeping pills and suggested to change his life lifestyle by doing yoga, meditation and some physical exercise. Mr. Angad followed his friend’s advice and after few days he started feeling better.

After reading the above passage, answer the following

(i) What are the values (at least two) displayed by Mr. Deepak?

(ii) Why is it not advisable to take sleeping pills without consulting doctor?

(iii) What are tranquilisers? Give two examples.

What is the role of CO in the extraction of Iron?

Write two factors that affect the rate of reaction.

For a reaction A + B ⟶ P, the rate is given by

Rate = k [A] [B]²

How is the rate of reaction affected if the concentration of B is doubled?

For a reaction A + B ⟶ P, the rate is given by

Rate = k [A] [B]²

What is the overall order of reaction if A is present in large excess?

Account for the following:

N₂ is less reactive at room temperature.

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?