Class 12th

This is a Multiple Answer Type Questions as classified in NCERT Exemplar

The Correct option is a.

Proteins contain one or more polypeptide chains. When each polypeptide of a protein's amino acids is joined in a precise order, a proteins' main structure is referred to as its primary structure. This one is the linear structure with no bonds other than the ones between adjacent amino acids. The sequence of amino acids in the primary structure is pre-determined by the genetic code of an individual and thus is a specific sequence.

This is a Multiple Choice Questions as classified in NCERT Exemplar

Ans:  (B) 

Diazonium salts react with copper powder and halogen acid to form aryl halide.

Gattermann reaction is a Sandmeyer reaction variant in which Cu powder replaces CuCl.

This substitution produces aryl halide more easily and under milder conditions than the Sandmeyer reaction.

This is a Multiple Choice Questions as classified in NCERT Exemplar

Ans: (A) 

On Reaction of acid anhydrides with primary amines, amides are formed as the primary product along with carboxylic acid. 

(RCO)₂O + RNH₂? RCONH₂ + RCOOH

This is a Multiple Choice Questions as classified in NCERT Exemplar

Ans:  (B) 

Greater will be the basic character, greater will be its reactivity towards dilute hydrochloric acid. As, (B), secondary amine, it will be the most basic among all and hence the most reactive amine towards acid. 

This is a multiple choice answer as classified in NCERT Exemplar

(b, d) Table salt and cane sugar are used, as food preservatives while sodium hydrogen carbonate and benzoic acid are not used as food preservatives.

This is a Multiple Choice Questions as classified in NCERT Exemplar

Ans: (C) 

Using active metals like iron in acidic conditions can be efficiently used for the reduction of nitro compounds. 

Under the acidic conditions, the intermediate compounds that may form are readily reduced to primary amine and pure product of primary amine is obtained. 

This is a multiple choice answer as classified in NCERT Exemplar

(b, d) Receptor proteins are embedded in the cell membrane and their active sites project outside region of the cell membrane. Shape of the receptor changes during the attachment of messenger.

This is a multiple choice answer as classified in NCERT Exemplar

(b) Artificial sweeteners are non-caloric substitutes for sugar. They are often intensely more sweet than sugar but do not enhance nutritional value of food. Vitamins and minerals are essential nutrients because they perform hundreds of roles in the body.

Amino acids will also enhance the nutritional value of food.

This is a Multiple Choice Questions as classified in NCERT Exemplar

Ans: (C)

In the process of nitration of benzene, firstly H₂SO₄ dissociates into H⁺ and HSO₄−. The proton produced further reacts with HNO₃ to give a positively charged complex that is unstable and dissociates into nitronium ions and water as products. The nitronium ion is an electron-deficient species i.e. electrophile that attacks the electron cloud of the benzene ring.

H₂SO₄  (conc.) ? H⁺+HSO₄⁻

H⁺+HNO₃? H₂NO₃⁺

H₂NO₃⁺? NO₂⁺ + H2O

This is a Multiple Choice Questions as classified in NCERT Exemplar

Ans: (B) 

Primary aliphatic amines react with nitrous acid to form aliphatic diazonium salts, which are unstable and release nitrogen gas and alcohol quantitatively.