Measuring Atmospheric Pressure

The diagram shows a manometer containing a liquid. The manometer is used to find the difference between the pressure of a gas and atmospheric pressure. Which distance represents this pressure difference?

• A

• B

• C

• D

The diagram shows a mercury barometer. Which distance is used to calculate the pressure of the atmosphere?

• 25cm

• 75cm

• 80cm

• 100cm

The diagram shows a simple mercury barometer. The atmospheric pressure increases. Which distance increases?

• V W

• W Y

• X Y

• X Z

Water manometer is used to measure the pressure of a gas supply to a house. It gives a reading of h cm of water. Why is it better to use water rather than mercury in this manometer?

• h would be too large if mercury were used

• h would be too small if mercury were used

• The tube would need to be narrower if mercury were used

• The tube would need to be wider if mercury were used

The pressure of a gas is measured using a manometer as shown in the diagram. The mercury in the manometer is replaced with a liquid that is less dense. How does the value of h change?

• It becomes zero

• It decreases but not to zero

• It stays the same

• It increases

The diagram show two mercury barometer standing side by side. The right-hand diagram shows a tube bigger diameter, but the diagram is incomplete. There is a vacuum above the mercury in both tubes. Which labelled position on the right-hand tube could show the mercury level in that tube?

• A

• B

• C

• D

A manometer is used to measure the pressure of air in a container. Which change would give a smaller value of height h?

• using a less dense liquid

• using a more dense liquid

• using a narrower tube

• using a wider tube

The diagram shows a manometer with one side connected to a gas cylinder and the other side open to the atmosphere. Which conclusion can be made using only the information from liquid levels in the manometer?

• density of gas < density of air

• density of gas > density of air

• pressure of gas < atmospheric pressure

• pressure of gas > atmospheric pressure

Explain what would happen to the column of mercury in the barometer as shown if the atmospheric pressure fell.

• As the pressure falls, the column of mercury will drop lower.

• As the pressure falls, the column of mercury will remain unchanged.

• As the pressure falls, the column of mercury will rise higher.

• As the pressure falls, the density of the mercury will increase.

The diagram shows an apparatus set up to measure atmospheric pressure.

Calculate the pressure at point Q.

• 10 cm Hg

• 85 cm Hg

• 90 cm Hg

• 15 cm Hg