The wood turns into ash and smoke so mass is nor destroyed or created.
The pressure of diver = atmospheric pressure + water pressure
atmospheric pressure = 750 mmHg (as given) = 750 / 760 atm = 0.987 atm
Water pressure is
P = hρg
where
h = height of water = 38 ft
1 ft = 0.3048
38 ft = 11.58 m
ρ = density = 1000 Kg / m³
g = gravitational constant = 9.81 m/s2
P = 11.58 X 1000 X 9.81 = 113599.8 Kg / m s^2 Or N /m^2
1 N / m^2 = 1 pa = 9.869 X 10^-6 atm
P = 113599.8 Pa = 1.12 atm
Total pressure = 1.12 + 0.987 atm = 2.107 atm = 2.1 atm (two significant figures)
I am pretty sure it is Vitamin A... but I could be wrong. Sorry if it is wrong.
