Identification of Common Gases Practice Questions

The gas was bubbled through limewater.

Limewater is an aqueous solution of one of the substances below.

Choose the correct substance.

• calcium carbonate
• calcium chloride
• calcium hydroxide
• calcium oxide

Give the result of the test if carbon dioxide is present.

The student tested a second sample of the gas with a glowing splint. The splint went out.

Explain what this tells the student about the gas.

Describe the test for chlorine gas.

Give the result of the test.

Test ...........................................................................

Result ...........................................................................

Suggest why the test on a sample of the gas is carried out in a fume cupboard.

A student placed a piece of magnesium ribbon in a test tube of dilute hydrochloric acid. A gas was collected in the top of the test tube.

The student predicted that the gas was hydrogen.

Describe the test the student could use to show that the gas is hydrogen.

Give the result of the test.

Test ...........................................................................

Result ...........................................................................

Which test is used to identify oxygen gas?

Tick one box.

• A burning splint is held at the open end of the test tube.
• A glowing splint is inserted into the test tube.
• Damp litmus paper is held in the gas.
• The gas is bubbled through limewater.

Give the result of this test if oxygen is present.

The student held a piece of damp blue litmus paper in the gas.

State what the student would observe.

Identify the unknown gas.

Explain how the first test shows that the gas is not hydrogen.

Explain how the second test shows that the gas is not chlorine.

The student's teacher said that only one of the three tests is needed to identify the gas.

Give this test and explain your answer.

A student passed chlorine gas over a piece of dry blue litmus paper. The paper did not change colour.

The student concluded that the gas was not chlorine.

Explain why this conclusion is not correct.

Another student has two test tubes of gas. One contains hydrogen and the other contains oxygen. The test tubes are not labelled.

Describe how the student could use a lit splint to find out which test tube contains hydrogen.