Test for carbon dioxide (Sec 3)

Okay, now this question came out in the 3B class test and it was kinda disappointing cos it was done in lab and who would have thought that hands on activity would not leave an impression with the students. For those who did not know, naturally left it blank, however, some had a vague impression and this was the answer.

"...add limewater to the solution, and it will turn chalky...."

2 mistakes... Firstly, we are testing for gas, so what does the word "solution" mean? The word "solution" means mixture in liquid state ... so it is kind of a contradicting as adding limewater in a liquid is not going to test for any gas.

I guess that is why most chemistry student do badly as they just write everything vaguely. Secondary 3/4 Science is not like Primary school science. More precise words need to be used.

Secondly, the word "chalky" is outdated. It will be marked as wrong. White solids are seen and in this case the solid has a name, called "precipitate" and I must mention someone spelt it as "perticipate" -_-"

Conclusion?

Test for carbon dioxide:

Bubble gas through calcium hydroxide (limewater) and white precipitate is formed.