Step first:
Since, 78.0 percent 
by volume is present in the air which implies there are 78 moles of present in 100 moles of air.
Now,
Mole fraction of = 
Mole fraction =
= 0.78
Partial pressure is equal to the multiplication of total pressure and mole fraction.
Partial pressure = 
(as 1 atm is atmospheric pressure)
= 0.78 atm.
Step second:
Henry's law constant is calculated by:
where,
is solubility of gas
is partial pressure of gas
is henry's law constant
Substitute the value of solubility and partial pressure to find the value of Henry's law constant in above formula:
k = 
= 
Thus, Henry's Law constant is 
.
<span>First, divide the mass of N2O by it's molar mass of 46 g/mol to determine the number of moles of N2O, then multiply that number by two since there are two moles of N in each mole of the compound N2O. This results in a final answer of 9.78X10^-3 moles of N in 0.225g of N2O.</span>
Answer is: near equivalence point indicator should change color, so we must pick indicator who changes color near pH of equivalence point.
Equivalence point is
the point which there is stoichiometrically equivalent amounts of acid and
base. <span>
<span>Chemist can draw pH curve (graph
showing the change in pH of a solution, which is being titrated) for
titration and determine equivalence point.</span></span>
Well physical would be if you have Clay and you molded into a new shape or if you put butter on your toes and it melts or water evaporating from the surface of the ocean chemical changes would be milk going sour jewellery tarnishing which means turning into a different color or rust bread putting it in the oven and turning it into toes or rust forming on the nail that is left outside
