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Haloalkanes and Haloarenes — Chemistry STD 12 Science — Question

Rajasthan BoardEnglish MediumSTD 12 ScienceChemistryHaloalkanes and Haloarenes4 Marks
Question
Read the passage given below and answer the following questions:
Consider the given sequence of reactions:

The following questions are multiple choice questions. Choose the most appropriate answer:
  1. Identify $W.$
  1. Compound $Y$ is:
  1. When $X$ reacts with $CH_3COCl$ in presence of anhy. $AlCl_3$, the reaction is known as:
  1. Benzene.
  2. Phenol.
  3. P-chlorophenol.
  4. Triphenyl.
  5. When $X$ is treated $Ni-Al/ \text{NaOH}$ the product obtained is:
  6. Fittig reaction.
  7. Ullmann reaction.
  8. Wurtz$-$Fittig reaction.
  9. Friedel$-$Crafts acylation reaction.
  1. Compound $Z$ is:
  1. Phenol.
  2. $P-$chlorophenol.
  3. $P-$nitrophenol.
  4. Nitrobenzene.
✓

Answer

  1. $(c)$

  1. $(c)$

  1. $(d)$ Friedel$-$Crafts acylation reaction.
  2. $(a)$ Benzene.
  1. $(c)\ P-$nitrophenol.

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  2. $\ce{CH_3CH=CHCOCH_3}$
  3. $\ce{(CH_3)_2C=CHCHO}$
  4. $\ce{(CH_3)_2C=CHCOCH_3}$
  1. Which combination of carbonyl compounds gives phenyl vinyl ketone by an aldol condensation?
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Arrange in order of increasing acid strengths. 
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  2. at $\ce{pH 7}$
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  1. A tripeptide $(X)$ on partial hydrolysis gave two dipeptides $\ce{Cys-Gly}$ and $\ce{Glu-Cys.}$ Identify the tripeptide.
  1. $\ce{Glu-Cys-Gly}$
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Read the passage given below and answer the following questions:
Pentose and hexose undergo intramolecular hemiacetal or hemiketal formation due to combination of the $–\ce{OH}$ group with the carbonyl group. The actual structure is either of five or six membered ring containing an oxygen atom. In the free state all pentoses and hexoses exist in pyranose form $($resembling pyran$).$ However,inthe combined state some of them exist as five membered cyclic structures, called furanose $($resembling furan$).$

The cyclic structure of glucose is represented by Haworth structure:

$\alpha$ and $\beta D-$glucose have different configuration at anomeric $(C-1)$ carbon atom, hence are called anomers and the $C-1$ carbon atom is called anomeric carbon $($glycosidic carbon$).$
The six membered cyclic structure of glucose is called pyranose structure.
The following questionsare multiple choice questions. Choose the most appropriate answer:
  1. $\alpha D(+)-$glucose and $\beta D(+)$ glucose are:
  1. Enantiomers.
  2. Conformers.
  3. Epimers.
  4. Anomers.
  1. The following carbohydrate is:
 
  1. A ketohexose.
  2. An aldohexose.
  3. An $n-$furanose.
  4. An $\alpha-$pyranose.
  1. In the following structure, anomeric carbon is:
  1. $C-1$
  2. $C-2$
  3. $C-3$
  4. $C-4$
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  2. A mixture of $(D)-$glucose and $(L)-$glucose.
  3. Enantiomers of glucose.
  4. Isomers of glucose that differ in configuration at carbon one $(C-1).$
  1. What percentage of $\beta-D-(+)$ glucopyranose is found at equilibrium in the aqueous solution?
  1. $50\%$
  2. $\approx100%$
  3. $36\%$
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Amines are basic in nature. The $pK_b$ value is a measure of the basic strength of an amine. Lower the value of $pK_b$ more basic is the amine. The effect of substituent on the basic strength of amines in aqueous solution was determined using titrations. The substituent $''X\ ''$ replaced $''-CH_2\ ''$ group in piperidine $($ compound $1)$ and propylamine $\ce{CH_3CH_2CH_2NH_2}, ($compound $2).$
Compound $1:$ Image
Compound $2: \ce{HXCH_2CH_2NH_2}$
Image
$($source: Hall $\text{Jr, H. K.} (1956).$ Field and inductive effects on the base strengths of amines. Journal of the American Chemical Society, $78(11), 2570-2572.)$
Study the above data and answer the following questions:
$a.$ Plot a graph between the electronegativity of the substituent vs $pK_b$ value of the corresponding substituted propyl amine $($given that $pK_a + pK_b =14).$ Is there any relation between the electronegativity of the substituent and its basic strength?
$b.$ The electronegativity of the substituent $''C_6H_5CON\ ''$ is $3.7,$ what is the expected $pKa$ value of compound $\ce{C_6H_5CONHCH_2CH_2NH_2}$?
$(i)\ 9.9\ (ii)\ 9.5\ (iii)\ 9.3\ (iv)\ 9.1$
$c.$ The pKa value of the substituted piperidine formed with substituent $''X\ ''$ is found to be $8.28.$ What is the expected electronegativity of $''X\ ''$
$(i)\ 3.5\ (ii)\ 3.4\ (iii)\ 3.8\ (iv)\ 3.1$
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Read the passage given below and answer the following questions: Fehling's reagent: Fehling's reagent is a mixture of two solutions. Fehllng's solution $A$ is aqueous copper sulphate solution. Fehling's solution Bis alkaline sodium potassium tartarate $($Rochelle salt$). \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \text{CH(OH)COONa}\\\text{CuSo}_{4\text{(aq)}}+|\\\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \text{CH(OH)COOK}$ It is a mild oxidising agent. It is weaker than Tollens' reagent. It oxidises only aliphatic aldehydes to carboxylate ions and itself gets reduced to reddish brown precipitate of cuprous oxide. Aromatic aldehydes do not respond to Fehling's test. This reaction is used for the test of aliphatic aldehydes known as Fehling's reagent test. In these questions $(Q$. No. $l-iv),$ a statement of assertion followed by a statement ofreason is given. Choose the correct answer out of the following choices.
  1. Assertion and reason both are correct statements and reason is correct explanation for assertion.
  2. Assertion and reason both are correct statements but reason is not correct explanation for assertion.
  3. Assertion is correct statement but reason is wrong statement.
  4. Assertion is wrong statement but reason is correct statement.
  1. Assertion : Fehling's solution can be used to distinguish between acetaldehyde and acetone.
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  1. Assertion : $\ce{CH_3CHO}$ and $\ce{C_6H_5CH_2CHO}$ cannot be distinguished chemically by Fehling's solution.
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  1. Assertion : Formaldehyde, when heated with Fehling's reagent produces a reddish brown ppt, of $\ce{Cu}$.
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