CBSE 12th Standard Chemistry Subject Alcohols , Phenols and Ethers Ncert Exemplar 2 Mark Questions With Solution 2021
By QB365 on 25 May, 2021
QB365 Provides the updated NCERT Exemplar Questions for Class 12, and also provide the detail solution for each and every NCERT Exemplar questions. NCERT Exemplar questions are latest updated question pattern from NCERT, QB365 will helps to get more marks in Exams
QB365 - Question Bank Software
CBSE 12th Standard Chemistry Subject Alcohols , Phenols and Ethers Ncert Exemplar 2 Mark Questions With Solution 2021
12th Standard CBSE
-
Reg.No. :
Chemistry
-
Name the enzmes and write the reactions involved in the preparation of ethanol from sucrose by fermentation.
(a) -
How can propan-2-one be converted into tert-butly alcohol?
(a) -
Write the structures if the isomers of alcohols with molecular formula C4H10O. Which of these exhibits optical activity?
(a) -
Explain why is OH group in phenols more strongly held as compound to OH group in alcohols.
(a) -
Explain why nucleophilic substitution reactions are not very common in phenols.
(a)
*****************************************
CBSE 12th Standard Chemistry Subject Alcohols , Phenols and Ethers Ncert Exemplar 2 Mark Questions With Solution 2021 Answer Keys
-
Invertase and zymase
\({ C }H_{ 12 }H_{ 22 }O_{ 11 }\overset { Invertase }{ \longrightarrow } \underset { Glucose }{ { C }_{ 6 }H_{ 12 }O_{ 6 } } +\underset { Fructose }{ { C }_{ 6 }H_{ 12 }O_{ 6 } } \)
\(\\ \underset { Glucose }{ { C }_{ 6 }H_{ 12 }O_{ 6 } } \overset { Invertase }{ \longrightarrow } \underset { Ethanol }{ { 2C }_{ 2 }H_{ 5 }OH } +2CO_{ 2 }\)
or Fructose -
\({ C }H_{ 3 }-\underset { \overset { \parallel }{ O } }{ C } -{ C }H_{ 3 }+{ C }H_{ 3 }MgBr\overset { Dry }{ \underset { ether }{ \longrightarrow } } \\ \quad \quad \quad \quad \quad \quad \quad \quad \quad \\ { C }H_{ 3 }-\overset { \underset { | }{ { C }H_{ 3 } } }{ \underset { \overset { | }{ { C }H_{ 3 } } }{ C } } \quad -OMgBr\overset { { H }^{ + }{ H }_{ 2 }O }{ \longrightarrow } \underset { tert-butyl\quad alcohol }{ \quad { C }H_{ 3 }-\overset { \underset { | }{ { C }H_{ 3 } } }{ \underset { \overset { | }{ { C }H_{ 3 } } }{ C } } \quad -OH } \)
-
\(\underset { (i) }{ { C }H_{ 3 }{ C }H_{ 2 }{ C }H_{ 2 }{ C }H_{ 2 }OH } \ \ \underset { (ii) }{ { C }H_{ 3 }{ C }H_{ 2 }\underset { \overset { | }{ OH } }{ C } H{ C }H_{ 3 } } ,\\ \underset { (iii) }{ { C }H_{ 2 }-\underset { \overset { | }{ OH } }{ C } H{ C }H_{ 2 }OH, } \underset { (iv) }{ \quad { C }H_{ 3 }-\overset { \underset { | }{ { C }H_{ 3 } } }{ \underset { \overset { | }{ { C }H_{ 3 } } }{ C } } \ -OH } \)
(ii) is optically active -
The OH group in phenol is more strongly held because of double bond character between C and O due to resonance.
-
OH group in phenols is a strong electron donating group. As a result, electron density on the benzene ring is quite high and hence it repeles nucleophiles. In other words nucleophiles cannot attack the benzene ring and hence phenol usually do not give nucleophiles. In other words, nucleophiles cannot attack the benzene ring and hence phenols usually do not hive nucleophilic substitution reactions.
