The industrial synthesis of nitric acid involves nitrogen dioxide with water to form nitric acid and nitrogen monoxide. Write and balance the equation. How many moles of nitric acid can be prepared by using 450 L of NO2 at a pressure of 5.00 atm and 295 K

Q1)
When the diver descends 34 feet;
total pressure on the diver - air pressure+ pressure from 34 feet of water 
air pressure - 1 atm
water pressure - 1 atm
therefore total pressure at 34 feet deep - 2 atm
Since water pressure increases with depth, according to the following equation;
P = hpg
h - height of water column above the point of pressure 
p - density of water
g - gravitational acceleration
P - pressure
as p and g are constant P is proportional to height, therefore when the height increases, pressure too increases proportionally
new height is 102 feet
that's 34*3 = 102 feet
so for every 34 feet, pressure increases by 1 atm
therefore at 102 feet - 1 atm times 3 = 3 atm
therefore total pressure at the new point = 1 atm (air pressure) + 3 atm (water pressure)  
total pressure = 4 atm

Q2)the reason why a person on land is not affected by the pressure exerted on him by the atmosphere around him is as the persons body too exerts an almost equal amount of pressure from inside. Therefore the pressure acting on him and pressure exerted by him is equalised so he wont feel the effect of atmospheric pressure.
Similarly when the person dives into water since the body also contains water inside, the pressure exerted on him by water is equal to the internal pressure coming from him. Therefore he won't feel a huge effect by the water pressure.
However the air spaces inside the person will have the pressure it had at the surface of water, but when the person has dived inside the water pressure is much higher therefore there's a pressure difference between that of the water pressure and pressure inside the air spaces. This may cause a squeeze where the air spaces tend to compress. To avoid this condition, the air spaces should be equalised.