What is the pressure exerted by a weight of 20 N, whose surface area in contact with the floor is 2 m?

Pressure ($P$) is defined as Force ($F$) per unit Area ($A$).

$$P = \frac{F}{A}$$

Given Force (Weight) $F = 20\ \text{N}$
Given Area $A = 2\ \text{m}^2$

$$P = \frac{20\ \text{N}}{2\ \text{m}^2}$$

$$P = 10\ \text{N/m}^2$$

The unit N/m² is also known as Pascal (Pa).

$$P = 10\ \text{Pa}$$

The final answer is $10\ \text{Pa}$.