Which of the following statements is not true about glucose?
Which of the following statements is not true about glucose?
Show Hint
- It is an aldose.
- On heating with HI it forms n-hexane.
- It exists in furanose form.
It does not give Schiff's test.
The Correct Option is A
Approach Solution - 1
The question asks which statement about glucose is not true. Let's evaluate each option:
- Glucose is an aldose: Glucose is indeed an aldose, as it contains an aldehyde group at the first carbon. Hence, this statement is true.
- On heating with HI, glucose forms n-hexane: This is a characteristic reaction where the entire glucose molecule reduces to n-hexane when treated with hydrogen iodide. Thus, this statement is also true.
- It exists in furanose form: Glucose typically forms a pyranose ring when cyclized, not a furanose form. Therefore, this statement is not true about glucose.
- It does not give Schiff's test: Glucose does not give a positive Schiff's test because while it contains an aldehyde group, it forms a stable cyclic hemiacetal form that typically doesn't react with Schiff's reagent. Hence, this statement is true.
Considering the analysis above, the statement that is not true about glucose is: It exists in furanose form.
Approach Solution -2
Step 1: Understanding glucose's properties. Glucose is an aldose (option A) and forms n-hexane on heating with HI (option B). It can exist in the furanose form (option C) as well.
Step 2: Schiff's test. Glucose, being an aldehyde, will give a positive Schiff's test, which detects aldehydes.
Step 3: Conclusion. Thus, the statement that glucose does not give Schiff's test is incorrect, corresponding to option (D).
Top CBSE CLASS XII Chemistry Questions
- ${AgNO_3}$ does not decompose where :
- Azeotropic mixture of water and HCl boils at 381.5 K. By distilling the mixture it is possible to obtain
Write IUPAC names of the following compounds and classify them into primary, secondary and tertiary amines.
(i) (CH3 )2CHNH2 (ii) CH3 (CH2 )2NH2 (iii) CH3NHCH(CH3 )2
(iv) (CH3 )3CNH2 (v) C6H5NHCH3 (vi) (CH3CH2 )2NCH3 (vii) m–BrC6H4NH2
Give one chemical test to distinguish between the following pairs of compounds.
(i) Methylamine and dimethylamine
(ii) Secondary and tertiary amines
(iii) Ethylamine and aniline
(iv) Aniline and benzylamine
(v) Aniline and N-methylanilineAccount for the following:
(i) pKb of aniline is more than that of methylamine.
(ii) Ethylamine is soluble in water whereas aniline is not.
(iii) Methylamine in water reacts with ferric chloride to precipitate hydrated ferric oxide.
(iv) Although amino group is o– and p– directing in aromatic electrophilic substitution reactions, aniline on nitration gives a substantial amount of m-nitroaniline.
(v) Aniline does not undergo Friedel-Crafts reaction.
(vi) Diazonium salts of aromatic amines are more stable than those of aliphatic amines. (vii) Gabriel phthalimide synthesis is preferred for synthesising primary amines.
Top CBSE CLASS XII Carbohydrates Questions
- Carbohydrates are essential for life in both plants and animals. Carbohydrates are used as storage molecules as starch in plants and glycogen in animals. Chemically, they are polyhydroxy aldehydes or ketones. On the basis of their behavior on hydrolysis, carbohydrates are classified as monosaccharides, oligosaccharides, and polysaccharides.
All monosaccharides are reducing sugars, i.e., they are oxidized by Tollens' reagent and Fehling’s solution. A monosaccharide like glucose is an aldose, and its molecular formula was found to be C6H12O6. After reacting with different reagents like HI, H2N–OH, Bromine water, (CH3)2O, etc., its structure was found to contain one aldehyde group, one primary alcoholic group (–CH2OH), and four secondary alcoholic groups (>CHOH).
Despite having the aldehyde group, glucose does not give some of the reactions of aldehyde groups like Schiff’s test or NaHSO3 addition. This explains the existence of glucose in two cyclic hemiacetal forms, which differ only in the configuration of the hydroxyl group at C–1. - What happens when D-glucose is treated with the following reagents?
(a) Br$_2$ water
(b) HCN - The suitable Grignard reagent used for the synthesis of
with methanal is: Write the reaction of glucose with:
(a) HI
(b) Br₂ water- Furanose ring of fructose is formed due to reaction between :
Top CBSE CLASS XII Questions
- 2, b, c are in A.P. and the range of determinant $\begin{vmatrix}1&1&1\\ 2&b&c\\ 4&b^{2}&c^{2}\end{vmatrix}$ is [2, 16]. Then find range of c is
- A boy of mass 50 kg is standing at one end of a, boat of length 9 m and mass 400 kg. He runs to the other, end. The distance through which the centre of mass of the boat boy system moves is
- A capillary tube of radius r is dipped inside a large vessel of water. The mass of water raised above water level is M. If the radius of capillary is doubled, the mass of water inside capillary will be
- A circular disc is rotating about its own axis. An external opposing torque 0.02 Nm is applied on the disc by which it comes rest in 5 seconds. The initial angular momentum of disc is
- A circular disc is rotating about its own axis at uniform angular velocity \(\omega.\) The disc is subjected to uniform angular retardation by which its angular velocity is decreased to \(\frac {\omega}{2}\) during 120 rotations. The number of rotations further made by it before coming to rest is