Correct Option
The correct option is (c) 1 and 3 only.
Explanation
Elements in the periodic table are broadly classified into metals, non-metals, and metalloids based on their physical and chemical properties. Metals typically exhibit characteristics such as hardness, luster, and conductivity, whereas non-metals generally lack these traits. Metalloids occupy the border between these two groups.
Statement-wise Analysis
- Statement 1 is Correct: Mercury is the only metal that exists in a liquid state at standard room temperature. While metals like Gallium and Cesium have very low melting points (slightly above room temperature), they are solid at standard room temperature (approx. 25°C).
- Statement 2 is Incorrect: Non-metals are generally non-lustrous (dull) and brittle. They are not malleable (cannot be beaten into sheets) or ductile (cannot be drawn into wires). Luster and malleability are characteristic properties of metals. (Iodine is a rare exception among non-metals regarding luster, but the general property holds true).
- Statement 3 is Correct: Metalloids (also known as semi-metals), such as Silicon, Germanium, and Arsenic, exhibit properties that are intermediate between those of metals and non-metals. For instance, they may look like metals but behave like semi-conductors chemically and electrically.
Key Takeaway: Metals are typically solid, lustrous, malleable, and ductile, with Mercury being the notable liquid exception. Non-metals are brittle and non-lustrous, while metalloids serve as the bridge with intermediate properties.