10 points for another 2 chemistry questions!!!!!!?

Question

I need some more help

how do you express 350 using scientific notation to 1 significant figures and to 4 significant figures?

how do find oxidation states in a balanced equation?

Answer 1

4 X 10^2

3.500 X 10^2

for oxidation states:

you always start with the element that is the in the right. for this element you take the charge from the periodic table. If there are three elements in a compound then do the same with the the left element. If there are only two elements, then take the total charge of the compound and subtract it from the charge of the right most element.

Examples:

BaS. S has a charge of -2. The total charge on the whole compound is 0, so the oxidation state is 0-(-2) = +2

H2SO4. O has a charge of -2 but since there are 4 of them its -8. H has a charge of 1 but since there are two of them its +2. the total charge is 0. So, its 0-(-8+2) = +6

Answer 2

I really hated chemistry...

Sorry but I can't help you with this I am better at other things =/