give 2 reason why all mineral cannot be absorbed passively ?

The minerals are mainly absorbed by the roots in the direct contact with the soil solution. Solute absorption categorized into passive absorption (Passive Transport) and Active absorption (Active Transport). All mineral cannot be absorbed passively and they grouped under Active absorption. 

Some of the reasons are 

• Some metabolic processes are energy derived. But passive absorption is physical in origin.
• Some ions and molecules are not spontaneous and do not proceed towards equilibrium.
• Molecule movement from its lower chemical potential to higher potential.