The graph shows the variation of pressure p with temperature θ for a fixed mass of an ideal gas at constant volume - AQA - A-Level Physics - Question 8 - 2018 - Paper 2

To find the gradient of the graph, we can select two clear points on the line. For example, let's take the points (0 °C, 0 Pa) and (20 °C, 100 Pa).

The formula for calculating the gradient (m) is:

$m = \frac{\Delta y}{\Delta x}$

Where:

• (\Delta y = 100 \text{ Pa} - 0 \text{ Pa} = 100 \text{ Pa})
• (\Delta x = 20 °C - 0 °C = 20 °C)

So, substituting the values in, we get:

$m = \frac{100 \text{ Pa}}{20 °C} = 5 \text{ Pa/°C}$

Thus, the gradient of the graph is 5.00.