How do you prepare hypophosphorous acid in the laboratory?

Hypophosphorous acid is

How would you prepare carbon dioxide in the laboratory? Describe its acidic nature and the action on lime water. What is photosynthesis ?

How would you prepare heavy hydrogen in the laboratory ?

How would you prepare very pure dihydrogen in the laboratory?

For the preparation of hydrochloric acid in the laboratory : Why is direct absorption of hydrogen chloride gas in water not feasible ?

How would you prepare dihydrogen from acids? Describe its laboratory preparation.

Taking hydrogen perioxide , how would you prepare oxygen in the laboratory ?

How would you prepare orthoboric acid from borax?

How is pure acetone prepared in the laboratory?

Give a reason why - For the preparation of nitric acid in the laboratory ,the complete apparatus is made up of glass.