The correct option is 2 only.
Explanation
Metals are generally characterized by high tensile strength and hardness. However, these physical properties are not absolute and depend on the strength of the metallic bonding within the crystal lattice structure of the specific element.
Statement-wise Analysis
- Statement 1 is Incorrect. Metals do not possess uniform hardness. The physical property of hardness is not constant across the periodic table; it depends on factors such as atomic size and the number of valence electrons contributing to the metallic bond.
- Statement 2 is Correct. The hardness of metals varies significantly. For example, transition metals like iron and copper are very hard, whereas mercury is a liquid at room temperature, and alkali metals are soft solids.
- Statement 3 is Incorrect. Alkali metals (such as Lithium, Sodium, and Potassium) are exceptions to the general rule of hardness. They have large atomic radii and weak metallic bonding, resulting in low density and softness. Consequently, they can be easily cut with a knife.
Key Takeaway
Key Takeaway: While metals are generally hard solids, alkali metals (Group 1 elements like Sodium and Potassium) are distinct exceptions, being soft enough to be cut with a knife.