I really need help with these chemistry questions that involve math ( thank you so much!) :)?

Question

******When the equation
__C8H16 + __O2 → __CO2 + __H2O
is correctly balanced using the smallest whole number coefficient, the coefficient of O2 is

a) 1
b) 8
c) 12
d) 16

******Given the balanced equation:

4Al(s) + 3O2(g) 2Al2O3(s)

What is the total number of moles of O2(g) that must react completely with 8.0 moles of Al(s) in order to form Al2O3(s)?

********A gas occupies a volume of 444 mL at 273 K and 79.0 kPa. What is the final kelvin temperature when the volume of the gas is changed to 1880 mL and the pressure is changed to 38.7 kPa?

a) 31.5 K
b) 292 K
c) 566 K
d) 2360 K

Answer 1

Guess you found the bad news about chemistry.
1. If you take one mole of the cyclooctane or whatever it is. It has enough carbon to create 8 moles of CO2 and 8 moles of H2O. The oxygen gas has to supply the O, 16 for CO2 and 8 for H2O. Since the 24 O comes from a dimeric gas, the coefficient is 12.

2. Moles react with moles. So for every 4 moles of Al, 3 moles of O2 are needed. For your problem, you form the simple proportion of
3/4 = x/8 . Real tough, eh?

3. Ideal gas time. PV= nRT. or PV/T= constant
So P1V1/T1= P2V2/T2. You know P1,V1 and T1 and P2 and V2. So do the rest.

Answer 2

C for the first question

6 for the 2nd qn

use the formula for the last one

did this with a minute...
you really should try them yourself, they aint that difficult

Answer 3

both of the question are c