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Multiple choice carbohydrates - definition and classification introduction to carbohydrates biomolecules chemistry

The products formed when a pinch of sugar is strongly heated for fifteen minutes in a test tube are:

  1. carbon and water vapour

  2. carbon, hydrogen and oxygen

  3. carbon dioxide and water vapour

  4. carbon dioxide and hydrogen
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Any carbohydrate will give water and $CO _2$ after combustion.

Example: Combustion of Glucose,
$C _6H _{12}O _6 + 6O _2 \xrightarrow{heat} 6CO _2 +6 H _2O$

Multiple choice carbohydrates - definition and classification introduction to carbohydrates biomolecules chemistry

When sugar is treated with sulphuric acid, we get a very pure form of:

  1. carbon

  2. oxygen

  3. water

  4. hydrogen
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

(A) carbon

Concentrated sulphuric acid is a strong dehydrating agent. Sulphuric acid removes water from organic compounds; it is evident by its charring action on carbohydrates.
${C} _{12}{H} _{22}{O} _{11} \xrightarrow{\text{ conc. } {H} _{2}S{O} _{4}} 12C + 11{H} _{2}O$

Multiple choice carbohydrates - definition and classification introduction to carbohydrates biomolecules chemistry

The light coming from the sun is stored as energy in plants by the process of photosynthesis. This happens by converting carbon dioxide and water into:

  1. green leaves

  2. carbohydrates

  3. fats

  4. plants hormones
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Photosynthesis is the process by which plants utilize the energy from the sunlight in order to convert carbon dioxide and water into carbohydrates.

Multiple choice carbohydrates - definition and classification introduction to carbohydrates biomolecules chemistry

Formula of glucose is :

  1. $C _{5}H _{12}O _{6}$
  2. $C _{6}H _{12}O _{16}$
  3. $C _{6}H _{12}O _{7}$
  4. $C _{6}H _{12}O _{6}$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Formula of glucose is $C _6H _{12}O _6$ it is derived from the reaction of photosynthesis that is :


$6CO _2 + 6H _2O \overset{Sunlight}\longrightarrow C _6H _{12}O _6 + 6O _2$

Hence, the correct option is D.

Multiple choice carbohydrates - definition and classification introduction to carbohydrates biomolecules chemistry

Which of the following compounds will not undergo decomposition on passing electricity through aqueous solution?

  1. Sugar

  2. Sodium chloride

  3. Sodium bromide

  4. Sodium acetate
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Sodium chloride, sodium bromide, and sodium acetate are all ionic compounds and hence, they dissociate into their respective ions in an aqueous solution. On the contrary, sugar is a covalent compound and hence does not dissociate into ions

Multiple choice carbohydrates - definition and classification introduction to carbohydrates biomolecules chemistry

The two functional groups present in a typical carbohydrate are :

  1. $-CHO$ and $-COOH$
  2. $-CO$ and $-OH$
  3. $-OH$ and $-CHO$
  4. $-OH$ and $-COOH$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Carbohydrates are polyhydroxy aldehydes or polyhydroxy ketones OR compounds which give aldehydic as well as ketonic groups on hydrolysis. Therefore the major functional groups are (carbonyl) Aldehyde, Ketone, and hydroxy groups. 

Multiple choice carbohydrates - definition and classification introduction to carbohydrates biomolecules chemistry

Out of $1$M glucose and $2$M glucose. 2M glucose has  a higher boiling point.

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

2 M glucose has a higher boiling point than 1 M of glucose.

Since on increasing the no of moles the molality also increases which is directly proportional to an elevation in boiling point.
Thus, the boiling point of the 2M of glucose will be greater than 1M glucose.