A diagram shows calcium floating on water. a) What physical property of calcium metal is demonstrated? b) What would be observed if water was replaced with dilute H2SO4?

Here are the answers to your questions:

1. a) What physical property of calcium metal is demonstrated in the diagram above? The physical property demonstrated is that calcium metal is less dense than water, as it floats on the surface of the water.

   b) What would be observed if water was replaced with dilute Sulphuric (VI) acid?

   • Effervescence (production of hydrogen gas) would be observed initially.
   • A white precipitate of calcium sulfate ($CaSO_4$) would form on the surface of the calcium metal.
   • The reaction would slow down and eventually stop as the insoluble calcium sulfate layer prevents further contact between the calcium and the acid.