Give reasons for the following:(i) Phenol is more acidic than et

Subject

Chemistry

Class

CBSE Class 12

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 Multiple Choice QuestionsShort Answer Type

21.

How do you convert the following:

(i) C6H5CONH2 to C6H5NH2

(ii) Aniline to phenol

(iii) Ethanenitrile to ethanamine

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22.

Write the chemical equations involved when aniline is treated with the following reagents:

(i) Br2 water
(ii) CHCI3 + KOH
(iii) HCl

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23.

Write the names and structures of the monomers of the following polymers:
(i) Buna-S
(ii) Glyptal
(iii) Polyvinyl chloride

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24.

(i) Write the product obtained when D-glucose reacts with H2N - OH.
(ii) Amino acids show amphoteric behaviour. Why?
(iii) Why cannot vitamin C be stored in our body?

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25. Write the structure of the major product in each of the following reactions:



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26.

Give reasons for the following:
(i) Phenol is more acidic than ethanol.
(ii) The boiling point of ethanol is higher in comparison to methoxymethane.
(iii) (CH3)3C - O - CH3 on reaction with HI gives CH3OH and (CH3)3C -I as the main products and not (CH3)3C -OH and CH3I.


An acidic substance is something that can produce hydrogen (H+) in water.

(i) Both ethanol and phenol are weak acids the ethanol is less acid then phenols because when phenol is dissolved in water it produce phenoxide ion by losing of proton and the phenoxide ion is stabilised by resonance.

 Ethoxide ion, however, is not stabilised by resonance. On the other hand, it is further destabilised by the positive inductive effect of the alkyl group.


     

(ii) Ethanol forms intermolecular hydrogen bonds due to the presence of hydrogen attached to the electronegative oxygen atom. As a result, ethanol exists as associated molecules while methoxymethane does not. Hence, the boiling point of ethanol is higher than that of methoxymethane.
      

(iii) Usually, iodide, being a big nucleophile, attacks on the group with low steric hindrance and the reaction proceeds by the SN2 mechanism.
However, in this case, methanol, on leaving generates a tertiary carbocation, which is more stable. Hence, this reaction proceeds by SN1 mechanism and therefore, we get (CH3)3C-I and CH3-OH as the major products.

      

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27.

Seeing the growing cases of diabetes and depression among young children, Mr Lugani, the principal of on reputed school organised a seminar in which he invited parents and principals. They all resolved this issue by strictly banning junk food in schools and introducing healthy snacks and drinks like soup, lassi, milk, etc. in school canteens. They also decided to make compulsory half an hour of daily physical activities for the students in the morning assembly. After six months, Mr Lugani conducted the health survey is most of the schools and discovered a tremendous improvement in the health of the students.
After reading the above passage, answer the following questions:

(i) What are the values (at least two) displayed by Mr Lugani?
(ii) As a student, how can you spread awareness about this issue?
(iii) What are antidepressant drugs? Give an example.
(iv) Name the sweetening agent used in the preparation of sweets for a diabetic patient.

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 Multiple Choice QuestionsLong Answer Type

28.

(a) Account for the following:

(i) Zr and Hf have almost similar atomic radii.

(ii) Transition metals show variable oxidation states. 

(iii) Cu+ ion is unstable in aqueous solution.

(b) Complete the following equations:

(i) 2 MnO2 + 4 KOH + O2--->

(ii) 2 Na2CrO4 + 2 H + -->

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29.

 bold E subscript bold M to the power of bold 2 bold plus end exponent bold divided by bold M end subscript superscript bold 0

Cr

Mn

Fe

Co

Ni

Cu

-0.91

-1.18

-0.44

-0.28

-0.25

-0.34


From the given data of E0 values answer the following Question:

(i) Which is strongest why is  value exceptionally positive?

(ii) Why is value highly negative as compared to other elements?

(iii) Reducing agent  Cr2+ or Fe2+? Give reason

 

(b) Why do actinoids show wide range f oxidation states? Write on the similarity between the chemistry of lanthanoids and actinoids.

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30.

 A compound 'A' of molecular formula C2H3OCl undergoes a series of reactions as shown below. Write the structures of A, B, C and D in the following reactions:

 

 

(b) Distinguish between the following:

(i) C6H5-COCH3 and C6H5 - CHO

(ii) Benzoic acid and methyl benzoate

(c) Write the structure of 2- methylbutanal.

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