An element is soft and can be cut with a knife. It is very reactive and cannot be kept open in the air. It reacts vigorously with water. The element is most likely to be:
Sodium is a highly reactive metal and catches fire easily when exposed to water and can be cut with a knife easily.
2Na+2H2O → 2NaOH+H2+ Heat
An element is soft can be cut easily with a knife.It is very reactive and cannot be kept open in the air.It reacts vigorously with water.This element is most likely to be: