[amp_mcq option1=”1 Pa” option2=”91 Pa” option3=”981 Pa” option4=”9810 Pa” correct=”option3″]
The correct answer is C. 981 Pa.
The pressure at a depth of 1 m below the free surface of a body of water is equal to the weight of the water column above it. The density of water is 1000 kg/m3, and the acceleration due to gravity is 9.8 m/s2. Therefore, the pressure is:
$P = \rho g h = 1000 \frac{kg}{m^3} \times 9.8 \frac{m}{s^2} \times 1 m = 981 Pa$
Option A is incorrect because it is the pressure at a depth of 1 cm below the free surface of water. Option B is incorrect because it is the pressure at a depth of 10 cm below the free surface of water. Option D is incorrect because it is the pressure at a depth of 100 cm below the free surface of water.