Which one of the following removes temporary hardness of water?

In the removal of temporary hardness of a sample containing $Ca^{2+}$,what is the number of moles of $Ca(OH)_2$ used per mole of $Ca(HCO_3)_2$ removed?

The compound used as a moderator in nuclear reactors is

Lead pipes are not suitable for drinking water because

When zeolite,which is a hydrated sodium aluminium silicate,is treated with hard water,the sodium ions are exchanged with which of the following?

Which of the following is the best scientific method to test the presence of water in a liquid?