Abhinav a class 9 student arranged the given setup to study the reactivity of some metals with water .he summerised his observations as follows:
1.In test tube p,there was no reaction in cold water but when th etest tube was heated for a while bubles of gas was seen.
2.In test tube Q,bubbles of gas were formed only after boiling the water .
3.In test tube R,no gas was produced even on boiling the water.
4.In test ube S,reaction occured vigirously.
The metals present in P,Q,R,S could be respectively