What are the elements obtained from sea water source?

What are the products obtained from the following reaction?

Heavy water is obtained by

Name the element present in sea-weeds.

An electric kettle has two heating elements. When one element is connected to an a.c. source the water boils in 10 min. When the other element is used the water boils in 40 min. If both elements are connected in parallel, the time taken by same quantity of water to boil is