Question

Which element would float in water?

1) Sodium

2) Magnesium

3) Cesium

4) Radium

Answer 1

It is Sodium because Lithium is not lighter than oxygen. It is, however, about half as dense as water. So it would float on water if it were not too busy reacting with it, like (but not as violently as) the related elements sodium and potassium.