identification of common gases

Question 1

how to test for hydrogen and how to know its positive

Answer 1

burning splint and ‘pop’ sound

Question 2

how to test for oxygen and how to know its positive

Answer 2

glowing splint and it relights the splint

Question 3

how to test for chlorine and how to know its positive

Answer 3

litmus paper and it bleaches the paper white

Question 4

how to test for carbon dioxide and how to know its positive

Answer 4

limewater and it goes cloudy (as a solid calcium carbonate forms)