Answer:

We do not have
- the amount of substance.

The molecular weight (
) of Bromine is 80.


Let (CH2O)n be molecular formula,
(12+1+1+16)n=90.08
30n=90.08
n=3
molecular formula: (CH2O) 3= C3H6O3
Answer : The initial mass of the sample is, 31.9 mg
Explanation :
Half-life = 4 days
First we have to calculate the rate constant, we use the formula :



Now we have to calculate the initial mass of sample.
Expression for rate law for first order kinetics is given by:

where,
k = rate constant = 
t = time passed by the sample = 12 days
a = initial amount of the reactant = ?
a - x = amount left after decay process = 4 mg
Now put all the given values in above equation, we get


Therefore, the initial mass of the sample is, 31.9 mg
Answer:
0.0660 moles
Explanation:
Change torr to atm and change celcius to kelvin.
(1.35L)(.987 atm)/(0.08206 L atm /mol k)(290k)
= 0.0660 mol