How to test for the presence of CO2 if the only apparatus you have are plain test tubes?

that’s just the thing =/ This came in an exam and now I am worried that what if it comes again in my exam (I have my Cambridge practical exam this Tuesday)

Carbon dioxide (lime water test)

To test for the presence of carbon dioxide gas, collect a sample of the gas in a small container such as a test tube. Add a small amount (2 to 3 ml) of lime water to the test tube and shake the test tube to mix the gas and the lime water.

If the lime water solution turns a milky white, the gas is carbon dioxide.

This test works because lime water and carbon dioxide gas react to form a white precipitate.

A second test is to light a wooden splint. Place the burning splint into the mouth of the test tube.

If the flame is extinguished, the gas may be carbon dioxide.

Since carbon dioxide is neither explosive nor does it support combustion, placing a burning splint into the mouth of the test tube containing carbon dioxide extinguishes the flame. This second test is not a positive test for carbon dioxide however since other gases may also extinguish a flame since they too do not support burning. Therefore, the first test is better!

wow, I cant believe I never thought of adding the lime water to the test tube. Feel very silly now!

Thankyou =)