Which type of paper best protects a divided hygroscopic powder?

Correct Answer: A

Rationale: Waxed paper (A) best protects hygroscopic powders (e.g., sodium chloride), its water-resistant coating preventing moisture absorption. Glassine (B) is grease-resistant, less moisture-proof. White bond (C) and blue bond (D) are absorbent, unsuitable. Vegetable parchment (original E) offers some resistance but less than wax. This barrier property maintains powder stability, critical in dispensing hygroscopic drugs, preventing clumping or degradation, ensuring accurate dosing and shelf life in humid conditions.

Correct Answer: D

Rationale: The Noyes-Whitney equation (D), dC/dt = kA(Cs - C), describes the rate of drug dissolution from a tablet, factoring surface area (A), solubility (Cs), and concentration (C), key in bioavailability (e.g., aspirin tablets). Fick's law (A) governs diffusion across membranes. Henderson-Hasselbalch (B) calculates pH-ionization. Law of mass action (C) is chemical equilibrium. Michaelis-Menten (original E) is enzyme kinetics. This equation guides formulation (e.g., particle size reduction), ensuring rapid dissolution for absorption, critical in solid dosage design.

Correct Answer: D

Rationale: The loading dose (D_L) is based on the apparent volume of distribution (V_D) and desired plasma concentration (D), calculated as D_L = V_D × C_p, ensuring rapid therapeutic levels (e.g., digoxin). Clearance (A) affects maintenance, not loading. Protein binding (B) and urinary excretion (C) influence free drug but aren't primary. AUC (original E) is outcome-based. V_D reflects tissue distribution, critical for initial dosing in drugs with large V_D, balancing speed and safety.

Correct Answer: A

Rationale: For a zero-order reaction, dA/dt = -k (A) is true, indicating a constant rate of drug elimination (e.g., ethanol above Km), independent of concentration. Option B (t₁₂=0.693/k) is first-order. Option C (A=A₀e⁻ᵏ) is first-order decay. No options D or original E exist, but C is incorrect here. Zero-order kinetics, rare in drugs, means half-life increases with dose, complicating dosing (e.g., phenytoin overdose), contrasting with first-order's constant half-life, key in pharmacokinetics.

Correct Answer: A

Rationale: Hydrolases (A) uncouple peptide linkages, cleaving bonds with water (e.g., pepsin in digestion), breaking proteins into amino acids. Ligases (B) form bonds. Oxidoreductases (C) handle redox. Transferases (D) move groups. Isomerases (original E) rearrange. Hydrolases' role in proteolysis impacts drug metabolism (e.g., prodrugs like enalapril) and digestion, central to biochemistry and pharmacology, affecting bioavailability and clearance.