Match List-I with List-II and select the correct answer from the codes given below the lists:
List-I (Substance)
A. Blue Vitriol
B. Eosin
C. Silver iodide
D. Zinc phosphide
List-II (Use)
1. Artificial

Question

Match List-I with List-II and select the correct answer from the codes given below the lists:
List-I (Substance)
A. Blue Vitriol
B. Eosin
C. Silver iodide
D. Zinc phosphide
List-II (Use)
1. Artificial rain
2. Fungicide
3. Red ink
4. Rodenticide

UnlockIAS · Accepted Answer

Correct — C, A-2, B-3, C-1, D-4. Blue Vitriol (copper sulphate pentahydrate, CuSO4·5H2O) is a fungicide — it is the copper source in Bordeaux mixture sprayed on crops and vines (A-2). Eosin is a bright red synthetic dye used to make red ink (and as a biological stain), so it maps to red ink (B-3). Silver iodide is seeded into clouds to trigger artificial rain: its crystal lattice resembles that of ice, so it nucleates ice crystals that grow into raindrops (C-1). Zinc phosphide is a rodenticide (rat poison) — in the rodent's acidic stomach it releases toxic phosphine gas (D-4). Only option (c) maps all four correctly.

Why the other options are wrong — (a) It swaps C and D — silver iodide is used for artificial rain (not as a rodenticide), and zinc phosphide is a rodenticide (not for artificial rain). Only its A-2 and B-3 are right.  (b) It wrongly makes Eosin the artificial-rain agent and Silver iodide the red ink. In fact Eosin is the red dye (red ink) and Silver iodide is the cloud-seeding agent (artificial rain).  (d) It wrongly makes Eosin a rodenticide and Zinc phosphide the red ink. Eosin is the red dye, while Zinc phosphide is the rodenticide (rat poison).

Concept: Several chemicals are known better by common/trade names than by their formulae, and each has a signature use. 'Blue Vitriol' is copper sulphate pentahydrate (CuSO4·5H2O), a fungicide (the copper in Bordeaux mixture). Eosin is a red dye used in red ink and in histological staining. Silver iodide (AgI) is the classic cloud-seeding agent for artificial rain because its crystal structure mimics ice. Zinc phosphide (Zn3P2) is a rodenticide that liberates poisonous phosphine gas in the stomach.

State PCS 2020 Q111 — Science & Technology PYQ with Answer

State PCS 2020 Q111 — Science & Technology PYQ with Answer