Multiple Choice QuestionsWhich one of the following is an amine hormone?
Thyroxine
Oxypurin
Insulin
Progesterone
Which one of the following statements is not true?
In vulcanization, the formation of sulphur bridges between different chains make rubber harder and stronger
Natural rubber has the trans-configuration at every double bond
Buna-S is a copolymer of butadiene and styrene
Natural rubber is a 1,4 polymer of isoprene
In DNA. the complimentary bases are
Adenine and thymine; guanine and cytosine
Adenine and thymine; guanine and uracil
Adenine and guanine, thymine: Guanine and uracil
Uracil and adenine; cytosine and guanine
Acetophenone when reacted with a base, C2H5ONa, yields a stable compound which has the structure
The relative reactivities of acyl compounds towards of nucleophilic substitution are in the order of
Acyl chloride> Acid anhydride> Ester> Amide
Ester > Acyl chloride> Amide > Acid anhydride
Acid anhydride > Amide > Ester> Acyl chloride
Acyl chloride > Ester > Acid anhydride > Amide
A.
Acyl chloride> Acid anhydride> Ester> Amide
The ease of nucleophilic substitution is depended upon the nature of leaving the group. When the leaving tendency of a group in a compound is high, then the compound is more reactive towards nucleophilic substitution.
The nucleophilic acyl substitution is completed in two-step as shown below.
The reactivity of the compound may be explained on the basicity of the leaving group. A weaker base is a better leaving group. The basicity order is as:
Cl- < RCOO- < RO- < NH-2
Hence, the order of leaving tendency is
In an SN2 substitution reaction of the type which 
one of the followings has the highest relative rate?
CH3-CH2-CH2Br
CH3-CH(CH2)-CH2Br
CH3C(CH3)2CH2Br
CH3CH2Br
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