Solve the following crossword with the help of the given clues :

Clues :
ACROSS
4. A list of metals arranged in order of their decreasing order.
5. Liquid hydrogen used as a _____ in rockets.
6. A chemical reaction involving removal of hydrogen or addition of oxygen.
10. High temperature flame produced by burning hydrogen in oxygen. Used for cutting and welding metals.
13. An isotope of hydrogen whose nucleus has one proton and one neutron. Also called heavy hydrogen.
14. A radioactive isotope of hydrogen whose nucleus has one proton and two neutrons.
16. The most abundant isotope of hydrogen. Its nucleus consists of a single proton. It does not have any neutron and its atomic mass is 1.
DOWN
1. Discoverer of hydrogen gas.
2. Water formed of oxygen and deuterium. It is like ordinary water but has higher freezing and boiling points.
3. A substance which can remove oxygen from a compound.
7. Scientist who gave hydrogen its present name.
8. A colourless, odourless and tasteless gaseous element that is the lightest and most abundant element in the universe.
9. Solidification of liquid vegetable oils by combining them chemically with hydrogen gas.
11. Reactions in which oxidation and reduction always occur simultaneously.
12. Gas produced by the action of hydrogen with nitrogen gas in the presence of iron as a catalyst.
15. A chemical reaction involving removal of oxygen or addition of hydrogen.

Explanation