What is the most efficient method to get water with zero degrees hardness?

What is the chemical formula of deuterosulphuric acid?

At high electric discharge hydrogen and oxygen combine to form _________

Reduction occurs at the anode.

What is a result of the reaction of heavy water with sodium?

Which of the following statements is true regarding the density of isotopes of the hydrogen?

The atomic number of hydrogen is 1.

What does D represent in heavy water?