Brain Teasers

I have made up some science and maths brain teasers and put them into four catagories. If you know the answer to one of them then put it in my PRIVATE guestbook along with the subject, difficulty and question number. When someone gets the correct answer I will put the answer on here and I'll give the person a little mention, plus, I'll put another puzzle into one of the other sections. there will only be a maximum of ten puzzles at any given time.

BIOLOGY
No physics puzzles have been created. Please wait for one to be created.

CHEMISTRY
1. (EASY) Can you work out the names/chemical symbols for all five of these? The first one is done for you. You may need the periodic table for this one!
Zn = Zinc
Au = (a)
(b) = Iron
(c) = Oxygen
H = (d)
(e) = Helium

2. (MEDIUM) This is a bit like the first one but it's compounds instead of elements. Again, the first one is did for you. There are only three this time.
H2O = Water
(a) = Carbon Dioxide
CH4 = (b)
(c) = Sodium Hypochlorite (Bleach)

3. (HARD) Number 1 and number 2 were the easy ones. Lets see if you can crack the next two! For NaOCl you have to find out it's real chemical name (c) and it's common name (d). CLUE: It has already been used in 1 or 2.
H2O (water) = 2 atoms of H (hydrogen) + O (oxygen)
(a) = C (carbon) + (b) atoms of O (oxygen)
NaOCl (c (d)) = Na (e) + O (oxygen) + Cl (f)

4. (IMPOSSIBLE) This one is a lot harder than any of the others on here. Whoever gets the correct answer should get a medal (but I'm out of medals).There will be no help, whatsoever, for this question.
Water's chemical formula is (a). It is made of (b) atoms of hydrogen and one atom of (c).
(d)'s chemical symbol is Au. It is a precious (e) often used in jewlery.
Carbon Dioxide is a compound. It's chemical (f) is CO2, meaning it has (g) carbon atom and two (h) atoms.
Sodium Hypochlorite, also known as (i), is a (j) with the chemical formula (k). This means it has one Sodium (l), one oxygen atom and one Chlorine atom.

Well done, you have finished the CHEMISTRY section. A new puzzle will be added every time an old one is completed. It may be added to any section (biology, chemistry, physics or maths.)

PHYSICS
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MATHS
1. (MEDIUM) In this puzzle you'll see there are six different questions. Each question comprises of only a number. The challenge is to find the square root of that number. The first one is done for you.
(a) 144 (square root = 12)
(b) 100
(c) 64
(d) 4
(e) 25
(f) 900

Thanks for reading my brain teasers. I hope this keeps you all satisfied until I make new ones. I have a few drafts for biology and physics but they may be a little too hard so I'll try them out on my mum and dad. If they're too hard I'll make some new ones.