Question

Glucose on prolonged heating with HI gives
A. n-Hexane
B. 1 hexane
C. Hexanoic acid
D. 6 iodohexane

Answer 1

Hint: Glucose is the energy source for the food synthesizing organisms. It is a monosaccharide sugar which undergoes glycolysis to provide energy. It is also called dextrose. It has ${C_6}{H_{12}}{O_6}$ as its molecular formula. Many other heterosaccharides are broken down to form glucose.

Complete answer:
 Glucose being a 6 carbon molecule can react with various other molecules.
HI – it is hydroiodic acid. It is liquid hydrogen iodide. It is a strong chemical reagent. It can readily ionize in water. It has a greater reducing ability. It is used to make acetic acid generally.

Option A: n-Hexane: Glucose in the presence of red phosphorus is when heated with HI – hydroiodic acid, it gives n-hexane. This shows that glucose has a straight six-carbon chain.

Option B: 1 hexane: It is crude oil. It is made from petroleum

Option C: Hexanoic acid: It is caproic acid. It is colourless and oily in texture. It is derived from hexane chains by addition of carboxylic acid groups making it an acid.

Option D: 6 iodohexane: It is formed by reduction of 1 chloro 6 iodohexane in the presence of nickel.

So the answer is option A: n-Hexane.

Note:
 Hexane is dangerous to human health if it comes in direct contact. It is generally used commercially to obtain other edible oils from vegetables. It is insoluble in water. Hexane can also be used in making glues for shoes and roofing. It is also useful in the textile industry. It is a colourless liquid with an odour like petroleum.