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:

83 An element reacts with oxygen to give a compound with a high melting point. This compound is also soluble in water. The element is likely to be: 84 Which one of the following four metals would be displaced from the solution of its salt by the other three metals? 86 Which of the following metal exists in the liquid state? 87 Which of the following non-metal is a liquid?