In an experiment, a test-tube full of chlorine water was inverted in chlorine water as shown in the diagram below and the set up left in sunlight for one day.
![ChemF2midt1q8](https://www.easyelimu.com/images/form_2_past_papers/mid_term_2021/chemf2mid/ChemF2midt1q8.PNG)
After one day, a gas was found to have collected in the test-tube
- Identify the gas
- How can the above gas be tested?