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Chemistry · 2026 · 3 marks
CBSE 2026 · Region 2 · Set 1 · Q28
(A) Define the following term: 2+1 (a) Reducing sugar (b) Differentiate between the following: (i) Fibrous proteins and globular proteins (ii)…
(A)
Define the following term : $\displaystyle 2+1$
(a)
Reducing sugar
(b)
Differentiate between the following :
(i)
Fibrous proteins and globular proteins
(ii)
Nucleotide and nucleoside
OR
(B)
Write the reaction of glucose with the following :
(a)
$\displaystyle \mathrm{H}_{2} \mathrm{~N}-\mathrm{OH}$
(b)
$\displaystyle \left(\mathrm{CH}_{3} \mathrm{CO}\right)_{2} \mathrm{O}$
(c)
$$ conc⋅ $\displaystyle \mathrm{HNO}_{3}$
Marking-scheme solution
.
(a) The Carbohydrates which reduce Fehling’s solution or Tollens’ reagent are
referred to as reducing sugars.
(b)(i)
Fibrous proteins : When the polypeptide chains run parallel and are held
together by hydrogen & disulphide bonds then fibre– like structure is
formed.
Globular proteins : This structure results when the chains of polypeptides
coil around to give a spherical shape.
(ii)
Nucleoside
-A
unit
formed
by
the
attachment of a base to sugar is
known as Nucleoside
-Nucleoside= Base +Sugar
Nucleotide
-When nucleoside is linked to
phosphoric acid, it is called
Nucleotide
-Nucleotide= Sugar + Base +
Phosphate
.
(a)
(b)
(c)
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CBSE Class 12 Chemistry past-paper question from the 2026 board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.