Match List-I with List-II and select the correct answer from the codes given below the lists:
List-I (Metal)
A. Sodium
B. Mercury
C. Silver
D. Lead
List-II (Property)
1. Good conductor of electricity

Question

Match List-I with List-II and select the correct answer from the codes given below the lists:
List-I (Metal)
A. Sodium
B. Mercury
C. Silver
D. Lead
List-II (Property)
1. Good conductor of electricity
2. Liquid at room temperature
3. Poor conductor of heat
4. Can be easily cut with knife

UnlockIAS · Accepted Answer

Correct — C, A-4, B-2, C-1, D-3. Sodium (A) is a soft alkali metal that can be cut with a knife → 4. Mercury (B) is the only metal that is liquid at ordinary room temperature (melting point about −39 °C) → 2. Silver (C) has the highest electrical conductivity of all metals, so it is the good conductor of electricity → 1. Lead (D) has a comparatively low thermal conductivity, making it a poor conductor of heat → 3. That gives A-4, B-2, C-1, D-3 = option (c).

Why the other options are wrong — (a) Makes sodium the liquid and mercury a poor heat conductor; in fact mercury is the liquid metal and sodium is the knife-soft one, so A and B are both misassigned.  (b) Calls sodium the best electrical conductor and lead a liquid; silver is the top conductor and only mercury is liquid, so every pair here is off.  (d) Right for sodium (4) and lead (3), but swaps mercury and silver — mercury is the liquid (2) and silver the conductor (1), so B and C are reversed.

Concept: The item tests each metal's most distinctive physical property. Alkali metals such as sodium are so soft they can be cut with a knife; mercury is unique among metals in being liquid at room temperature; silver leads all metals in electrical conductivity; and lead has a relatively low thermal conductivity, so among these four it is the poor conductor of heat.

State PCS 2020 Q107 — Science & Technology PYQ with Answer

State PCS 2020 Q107 — Science & Technology PYQ with Answer