Koun Banega Karodpati question

Recently when I was watching Koun Banega Karodpati program, I came across this question.

Question 

What is at gaseous state in room temperature ?

1.  Oxygen 

2. Mercury 

3. Iron

4. Chlorine 

Now let us try to answer this question. 

At room temperature, mercury is always in liquid state.

Iron is always at solid state. 

We all know that oxygen is always in gaseous state. 

Wait...... Wait..... 

What about chlorine ?

Since my  school days , I have always thought that

Chlorine is present in the gaseous state at room temperature...... 

According to that, both Chlorine and Oxygen will be the answer to the question.

But contestant replied oxygen. 

Amitabh Bacchan said it is the correct answer........ 

My doubt remained as it is ........