The presence of an air bubble in the eudiometer would lead to an inaccurate measurement of the radius 'r' and affect the pressure reading, which could result in an incorrect calculation of the ideal gas constant 'R'.
If an air bubble is trapped in the eudiometer before starting the experiment, the resulting value of r, which represents the radius of the bubble, would be affected. According to the principles of gas behavior in bubbles, the pressure inside a bubble is greatest when the bubble is the smallest. Therefore, if a hole were made in the bubble or if it were not accounted for correctly, the air would be forced out, causing the bubble to decrease in radius, which would in turn affect the measured pressure.
In the context of the experiment, this means that any measurements taken would not be accurate representations of the intended conditions, as the presence of the bubble introduces an error. The pressure readings may be skewed, and as a result, when substituted into the ideal gas equation to solve for the ideal gas constant R, the value obtained may not be accurate. This is because R is dependent on the precise measurements of pressure, volume, and temperature, and any discrepancies can lead to an incorrect calculation of R.