Which of the following vitamins are fat soluble?

Correct — option (3), A and D.

NCERT's Class 12 Chemistry unit Biomolecules sorts vitamins by solubility. Fat soluble vitamins are those "soluble in fat and oils but insoluble in water", and NCERT names them: "vitamins A, D, E and K".

The other group is water soluble: "B group vitamins and vitamin C are soluble in water".

Option (3) is the only pair in which both vitamins come from the fat-soluble group. So the answer is A and D.

The idea to remember: fat soluble = A, D, E, K; water soluble = the B group and C.

Why the others are wrong

• (1)
  C and E — Vitamin E is fat soluble, but vitamin C is water soluble, so the pair fails.

  NCERT lists vitamin C (ascorbic acid) from citrus fruits, amla and green leafy vegetables, with scurvy (bleeding gums) as its deficiency disease. Vitamin E comes from vegetable oils such as wheat germ oil and sunflower oil.

• (2)
  A and C — Vitamin A is fat soluble, but vitamin C is water soluble, so only half of the pair is right.

  NCERT gives vitamin A's sources as fish liver oil, carrots, butter and milk, and its deficiency diseases as xerophthalmia and night blindness.

• (4)
  B₁₂ and D — Vitamin D is fat soluble, but vitamin B₁₂ belongs to the water-soluble B group.

  B₁₂ is the one water-soluble vitamin NCERT says can be stored in the body; the rest are readily excreted in urine. Being storable does not make it fat soluble. Its deficiency causes pernicious anaemia.

NCERT describes vitamins as organic compounds required in the diet in small amounts for specific biological functions. Most cannot be made in our body, though gut bacteria can produce some.

Vitamins are grouped by solubility. Fat soluble vitamins A, D, E and K dissolve in fats and oils and are stored in the liver and adipose (fat-storing) tissues.

Water soluble vitamins, the B group and C, must be supplied regularly in the diet because they are readily excreted in urine and, except B₁₂, cannot be stored.

Key facts

• NCERT: fat soluble vitamins are A, D, E and K; they are stored in the liver and adipose tissues.
• NCERT: the B group vitamins and vitamin C are water soluble.
• NCERT: water soluble vitamins are readily excreted in urine and cannot be stored, except vitamin B₁₂.
• NCERT deficiency diseases: A — xerophthalmia and night blindness; D — rickets and osteomalacia; K — increased blood clotting time.
• NCERT deficiency diseases: C — scurvy (bleeding gums); B₁₂ — pernicious anaemia.

Common traps

• One right vitamin is not enough: options (1) and (2) each pair a fat-soluble vitamin with vitamin C, which is water soluble.
• Stored does not mean fat soluble: NCERT says vitamin B₁₂ can be stored, yet it belongs to the water-soluble B group.
• Check against the set A, D, E, K: any pair containing a B vitamin or vitamin C cannot be fully fat soluble.

• practice — not a real PYQ

  According to NCERT, which water-soluble vitamin can be stored in the body?

  • (a)Vitamin C
  • (b)Vitamin B₁
  • (c)Vitamin B₁₂
  • (d)Vitamin B₆
  Answer(3) — NCERT says water-soluble vitamins are readily excreted in urine and cannot be stored in the body, except vitamin B₁₂. Options (1), (2) and (4) are water soluble and are not the exception NCERT names.
• practice — not a real PYQ

  Deficiency of which vitamin causes increased blood clotting time?

  • (a)Vitamin A
  • (b)Vitamin K
  • (c)Vitamin D
  • (d)Vitamin C
  Answer(2) — NCERT's table gives increased blood clotting time for vitamin K deficiency. Option (1) causes xerophthalmia and night blindness, option (3) rickets and osteomalacia, and option (4) scurvy.