Q.Match the compounds given in Column I with the effects given in Column II.
Column I:

Chloramphenicol works by binding to the 50S subunit of the bacterial ribosome, inhibiting protein synthesis. This action stops bacterial growth but does not directly kill the bacteria — that is the hallmark of a bacteriostatic agent. Bactericidal antibiotics (like penicillin) actively kill bacteria, often by disrupting cell walls or DNA replication. The key distinction: bacteriostatic drugs rely on the host immune system to clear the inhibited bacteria, while bactericidal drugs do the killing themselves.

Now, let’s examine each option:

1. Option (A): "It is a broad spectrum antibiotic"

   Chloramphenicol is effective against both Gram-positive and Gram-negative bacteria, as well as some anaerobes and rickettsiae. This is correct — it is indeed broad spectrum.

2. Option (B): "It is a bacteriostatic antibiotic"

   At therapeutic concentrations, chloramphenicol reversibly inhibits protein synthesis, halting bacterial multiplication. This is the correct description — it is bacteriostatic.

3. Option (C): "It is a bactericidal antibiotic" …

Concept & Intuition

Antihistamines are drugs that counteract the effects of histamine, a chemical released during allergic reactions. They work by blocking histamine receptors (mainly H₁ receptors) in the body, reducing symptoms like sneezing, itching, and runny nose. Common over-the-counter antihistamines include diphenhydramine (Benadryl), loratadine (Claritin), and cetirizine (Zyrtec). In the options, we need to identify which pair consists solely of drugs that act as antihistamines.

Step-by-step reasoning

1. Examine option (A): Dimetapp and Seldane

   • Dimetapp is a brand name for a combination of brompheniramine (an antihistamine) and a decongestant.
   • Seldane (terfenadine) was a widely used non-sedating antihistamine (now withdrawn in many countries due to cardiac risks).
   • Both are antihistamines. This pair fits.

2. Examine option (B): Iproniazid and Nardil

   • Iproniazid and Nardil (phenelzine) are monoamine oxidase inhibitors (MAOIs), used as antidepressants.
   • They have no antihistamine action. This pair is incorrect.

3. Examine option (C): Veronal and Valium

   • Veronal (barbital) is a barbiturate sedative-hypnotic.
   • Valium (diazepam) is a benzodiazepine anxiolytic.
   • Neither is an antihistamine. This pair is incorrect. …

This is a straightforward classification question from medicinal chemistry. The key is to know the therapeutic class of each drug: antihistamines, analgesics, tranquilizers, and antibiotics. Depression and hypertension are not treated by the same drug unless it’s a tranquilizer that also lowers blood pressure — that’s exactly what Equanil does.

1. Identify the drug classes

   • Ranitidine is an H₂-receptor antagonist (antihistamine) used for gastric ulcers and acid reflux — not for depression or hypertension.
   • Paracetamol (acetaminophen) is an analgesic and antipyretic (pain reliever and fever reducer) — no effect on mood or blood pressure.
   • Equanil (generic name: meprobamate) is a tranquilizer — it reduces anxiety, tension, and can lower blood pressure by calming the central nervous system.
   • Chloramphenicol is a broad-spectrum antibiotic — used for bacterial infections, not mental health or hypertension.

2. Match the description

   The question says “controlling depression and hypertension.” While Equanil is primarily an anti-anxiety drug (not a first-line antidepressant), it is historically used for mild anxiety and tension that can accompany depression, and it has a mild hypotensive effect. Among the options, it is the only one that fits both conditions.

3. Eliminate the others …

The key concept here is nomenclature of organic dihalides — specifically, how the positions of two halogen atoms on a carbon chain are described. The prefixes "vicinal" and "geminal" come from Latin: vicinus meaning "neighbor" and geminus meaning "twin." This immediately tells you the spatial relationship.

1. Understand the definitions

   • A vicinal dihalide has the two halogen atoms on adjacent carbon atoms (e.g., 1,2-dibromoethane).
   • A geminal dihalide has both halogen atoms on the same carbon atom (e.g., dichloromethane, CH₂Cl₂).
   • Terms like $\alpha,\beta$- or $\alpha,\gamma$-dihalide refer to positions relative to a functional group (often a carbonyl), not to the general case of two halogens on the same carbon.

2. Apply to the given condition

   The problem states: "When two halogen atoms are attached to the same carbon atom." This matches the definition of geminal (from Latin gemini = twins). No other option fits:

   • (A) Vicinal → adjacent carbons. …

Let’s go through each option carefully.

1. Option (A): Distillation of calcium acetate with calcium formate When a calcium salt of a carboxylic acid is dry distilled, it typically gives a ketone. For example, calcium acetate alone yields acetone:

If calcium formate is mixed with calcium acetate, the reaction produces a mixture of aldehydes and ketones. Specifically, calcium formate gives formaldehyde, and the mixed distillation yields acetaldehyde and acetone — not acetic acid. Acetic acid is not obtained this way. So this statement is false.

2. Option (B): Use in curing meat and fish

   Acetic acid (as vinegar) is indeed used as a preservative in pickling and curing meat and fish. Its acidic environment inhibits bacterial growth. This statement is correct.

3. Option (C): Glacial acetic acid

   Pure (anhydrous) acetic acid freezes at $16.6\,^\circ\mathrm{C}$, forming ice-like crystals. Hence the name "glacial". This is a standard fact. Correct. …