Antioxidants are regarded as sacrificial compounds, which themselves being more reactive towards oxygen prevent the oxidation of the preserved substance.
BHA and BHT are phenolic compounds used as antioxidants for the packaged foods as oxygen reacts preferentially with them rather than with the fat in the food.

They are more effective when used with ascorbic acid as it produces a synergic effect.

[CH₃(CH₂)₁₅N⁺(CH₃)₃]Br^-
Cetyltrimethylammonium bromide is a cationic detergent and the cleansing action is due to the cationic part of the molecule. Hence, it is called an invert soap.

The detergents having unbranched hydrocarbon side chain are preferred because they are biodegradable. This is because the unbranched side chain is more prone to attack by bacteria.

Statement 1 is correct but rest of the statements are incorrect as explained below:
Statement - 2 : Substrate molecules bind to the active sites of the enzyme through a variety of interactions like hydrogen bonding, dipole-dipole interactions, Vander Waal's forces of attraction, etc. but not a covalent bond.
Statement - 3 : In the competitive inhibition, drugs bind to the active site of the enzyme.
Statement - 4 : Non-competitive inhibitor binds to the allosteric site of the enzyme.

Hormones - secretions of endocrine glands
Neurotransmitters - communicate messages between two neurons and those between neurons and muscles
Antagonists - bind to the receptor site and inhibit its natural functioning
Agonists - mimic the natural messenger

The drug that competes with the enzyme by binding at the active site of the substrate is a competitive inhibitor.

p-Hydroxybenzoate esters are less effective on bacteria.

Orange - I is a derivative of sulphanilic acid and is acidic in nature.

Aspirin are not advised to be taken on an empty stomach because it gets hydrolysed to salicylic acid, which can cause hyper acidity and may result in ulcer in extreme cases.

Statements A and C are incorrect as explained below:

Statement A: Chemical messengers are received at the binding sites of the receptor proteins.In order to accommodate the messenger, the shape of the receptor site changes.
Statement C: Receptor proteins are embedded in the cell membrane in such a way that a small part possessing the active site projects out of the surface of the membrane and opens on the outside region of the cell membrane.