Biomolecules

Step 1: Recall the relation between van’t Hoff factor ( ) and degree of dissociation ( ) for an electrolyte: where = number of ions produced per formula unit.
Step 2: Barium nitrate ( ) dissociates as: So, .
Step 3: Substitute the given into the formula:
Step 4: Solve for :
Step 5: Convert to percentage:

Step 1: Recall that haemoglobin is the oxygen-carrying protein present in red blood cells.
Step 2: Carbon monoxide (CO) has a very high affinity for haemoglobin—about 200–250 times greater than oxygen.
Step 3: When CO binds with haemoglobin, it forms a stable compound called carboxyhaemoglobin.
Step 4: This prevents haemoglobin from carrying oxygen, leading to oxygen deficiency in tissues.
Step 5: Therefore, haemoglobin forms carboxyhaemoglobin with carbon monoxide (CO).

Step 1: Analyse Statement–I. In aqueous solution, glucose predominantly exists in the pyranose (six-membered ring) form. In free glucose, the anomeric carbon (C-1) contains a free hydroxyl ( ) group, which is responsible for its reducing nature.
Step 2: Analyse Statement–II. Sucrose is a disaccharide formed by: Thus:
Glucose unit is in pyranose form
Fructose unit is in furanose form
Step 3: Conclude. Since both statements are correct:

Step 1: Acid initially = 20 mL of 0.1 M
Step 2: Back-titrated by 15 mL NaOH
Step 3: Acid reacted with NH
Step 4: In Kjeldahl 1 mole N → 1 mole NH neutralizes 1 mole HCl. Therefore
Step 5: Mass of N
Step 6: Sample mass 29.5 mg = 0.0295 g. Hence → (C).

Step 1: Understand the process of rusting. Rusting is a chemical reaction in which iron reacts with oxygen and moisture to form hydrated iron(III) oxide. Step 2: Consider the effect on mass. During rusting:

Oxygen from the air combines with iron.
Additional mass is added to the iron nail.
Step 3: Analyze the options.

(A) Incorrect — weight does not decrease
(B) Correct — weight increases due to addition of oxygen ✔
(C) Incorrect — weight does change
(D) Incorrect — iron is oxidised, not reduced
Step 4: Final conclusion. The rusting of an iron nail increases its weight.