Which of the following is NOT a characteristic of metals?
A. Brittleness
B. Ductility
C. Malleability
D. High thermal conductivity
Answer: Option A
Solution (By JKSSB Mock Tests)
Brittleness is a property typical of non-metals and metalloids; metals are ductile and malleable, not brittle. Ductility: drawn into wires (gold most ductile). Malleability: beaten into sheets (gold most malleable). Metals also have luster, high thermal and electrical conductivity, and sonorous nature. Brittle substances break easily under stress without significant deformation (e.g., glass, sulfur). Some metals like cast iron are brittle but generally pure metals are not.
Explanation:
Chadwick (1932) produced highly penetrating neutral radiation by bombarding Be with α-particles, identified as neutrons. Reaction: ⁹Be + ⁴He → ¹²C + ¹n.
Explanation:
Dalton proposed that all atoms of a given element are identical in mass and properties. The discovery of isotopes (atoms of same element with different mass) contradicted this. Dalton's theory explained the three laws of chemical combination. Later models modified the theory. Subatomic particles and radioactivity also could not be explained by Dalton.
Explanation:
Flammability describes how a substance reacts with oxygen to burn, which is a chemical change. Boiling point, density, and melting point are physical properties because they can be observed without changing the chemical identity of the substance. Chemical properties are only observed during a chemical reaction.
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