Correct Answer - Option 4 : Carbon
Sodium, Potassium and Lithium are very soft metal can be very easily cut with a knife, just like wax.
- These metals have large size and only 1 electron in their valence shell, due to this the atomic bonding is quite weak.
- Also, these metals have body centred cubic structure that has a lot of empty space and this makes metallic bond weak.
- Hence, these can be easily cut using a knife.
- Carbon is hard non-metal it cannot be cut easily with a knife as they have stronger covalent bonds.