Answer: W = 6.4x10⁻²¹J
Explanation: <u>Work</u> is the energy transferred to or from an object due to the application of a force along a displacement.
The ion Na is gaining energy to move from a lower potential to a higher one.
For this to happen, the work done is calculated as

in which
W is work in Joules (J)
q is charge in Coulomb (C)
is potential difference in Volts (V)
The ion Na has one positive charge. In coulombs, the charge is
q = 1.6x10⁻¹⁹C
The potential difference in Volts is
= 40x10⁻³ or 4x10⁻²V
Calculating

W = 1.6x10⁻¹⁹. 4x10⁻²
W = 6.4 x 10⁻²¹ J
The work done to move an ion of sodium from the exterior to the interior is 6.4 x 10⁻²¹ J.
The theory that is demonstrated by this experiment is natural selection.
Basically, only the strongest bacteria survived, and nature decided which of those bacteria were fit enough to get to live and reproduce in the future. Those bacteria that were "willing" and able to fight their way through a huge number of bacteria were the ones who ultimately won.
Answer:
the gas bladder in fishes as it can help them to maintain their buoyancy in water