An atom is the smallest you can get to identify the element.
The pressure at the bottom : 19600 N/m²
<h3>Further explanation</h3>
Given
A ground water tank has its height 2m
Required
The pressure at its bottom
Solution
Hydrostatic pressure is the pressure caused by the weight of a liquid.
The weight of a liquid is affected by the force of gravity.
The hydrostatic pressure of a liquid can be formulated:

Ph = hydrostatic pressure (N / m², Pa)
ρ = density of liquid (kg / m³)
g = acceleration due to gravity (m / s²)
h = height / depth of liquid surface (m)
ρ = density of water (kg / m³) = 1000
g = acceleration due to gravity = 9.8 m/ sec²
The pressure

This problem is providing information about the initial mass of mercury (II) oxide (10.00 g) which is able to produce liquid mercury (8.00 g) and gaseous oxygen and asks for the resulting mass of the latter, which turns out to be 0.65 g after doing the corresponding calculations.
Initially, it is given a mass of 10.00 g of the oxide and 1.35 g are left which means that the following mass is consumed:

Now, since 8.00 grams of liquid mercury are collected, it is possible to calculate the grams of oxygen that were produced, by considering the law of conservation of mass, which states that the mass of the products equal that of the reactants as it is nor destroyed nor created. In such a way, the mass of oxygen turns out to be:

Learn more:
The paper clips will magnetically connect to the nail. With the copper wire wrapped around then nail, it makes a magnetic field that, when powered will cause metal objects to come toward it, hence why it is called an "electromagnet".
Hope this helps!!!