Answer : The time passed in years is 
Explanation :
Half-life of carbon-14 = 5730 years
First we have to calculate the rate constant, we use the formula :



Now we have to calculate the time passed.
Expression for rate law for first order kinetics is given by:

where,
k = rate constant = 
t = time passed by the sample = ?
a = initial amount of the reactant disintegrate = 15.3
a - x = amount left after decay process = 14.8
Now put all the given values in above equation, we get


Therefore, the time passed in years is 
Answer:
B and BBr3
Explanation:
1) 3HBr + B = BBr3 + H2 (double all equation because H2)
2) 6HBr + <em>2B </em>= <em>2BBr3</em> + 3H2
Its FeSO3 or iron(iii)sulfite = Fe2(SO3)3
We can solve this problem when we use the conditions of a gas at standard temperature and pressure. It has been established that at STP where the temperature is 0 degrees Celsius and the pressure is 101.325 kPa, the volume of 1 mole of gas is 22.4 L. We will use this data for the calculations.
68.5 L ( 1 mol O2 / 22.4 L O2 ) = 3.06 mol O2