Question

Atmospheric pressure recorded by a simple barometer is 75 cm of mercury. The atmospheric pressure in pascal is: (g = 9.8m/s²)

• A. 99900 Pa
• B. 99990 Pa
• C. 99960 Pa
• D. 99999 Pa

Answer 1

The correct option is C

99960 Pa

Explanation for the correct option

Step 1. Given data

Height of mercury, $h=75cm=75/100m=0.75m$

Acceleration due to gravity, $g=9.8m/s^2$

Step 2. Formula used

Pressure, $P=\rho gh$……….(a)

Step 3. Calculation of pressure

We know the density of mercury, $\rho =13600kg/m^3$

Substituting the given values and density of mercury in equation (a), we get

$$\begin{gathered} P=13600\times 9.8\times 0.75 \\ P=99960N/m^2 \\ P=99960Pa \end{gathered}$$

Hence, option (c) will be correct.