Answer:
Increases
Step-by-step explanation:
Alkali metal react vigorously with water (For eg sodium in water). In this process, H2 gas is given off and the metal hydroxide is produced.
The speed and the observed violence of the reaction increases as you go down the group or in other words, The Group 1 metals become more reactive towards water as you go down the Group.
This trend is observed because it takes less energy for reaction to occur with water as you move down the group. Lower activation energies = faster reactions