Question

Why some group l metals can be cut with a knife? Give examples .

Answer 1

some metals can be cut with a knife because :::::::::
===Due to the presence of weak metallic bonding alkali metals are soft and can be cut with a knife.
===Alkali metals have large atomic size with only one valence electron. Therefore, they have weak metallic bonding between the atoms. Due to the presence of weak metallic bonding alkali metals are soft and can be cut with a knife.
===Reactivity of metals depends on ionization energy or ionization enthalpy. Ionization enthalpy of an element depends on its atomic radius
some examples are lithium, sodium, potassium, rubidium, cesium, and francium. 

Answer 2

as they are alkali metals and they are soft . thus they can be cut with the help of knife.for eg sodium