3 protons should be your answer
The combustion of fossil fuels is releasing more co2 into the atmosphere then what would occur naturally
#1
As we know that

now plug in all data into this


now from the formula of strain




#2
As we know that
pressure * area = Force
here we know that


now force is given as

#3
As we know that density of water will vary with the height as given below

here we know that


now density is given as


#4
as we know that pressure changes with depth as per following equation

here we know that

now we will have



here we will have

so it is 20.1 m below the surface
#5
Here net buoyancy force due to water and oil will balance the weight of the block
so here we will have




so it is 3.48 cm below the interface
To solve this problem we will apply the concepts related to volume, as a function of length and area, as of mass and density. Later we will take the same concept of resistance and resistivity, equal to the length per unit area. Once obtained from the known constants it will be possible to obtain the area by matching the two equations:
Mass of copper wire
Density
Resistively of copper 
Resistance (R) = 0.390\Omega
Volume is defined as,

(1)
We know that,


(2)
Multiplying equation we have




Therefore the length of the wire is 1.68m