Question

We cannot see the oxygen that we breathe. It is freely available in the air, from which it is obtained for industrial purposes by liquefying it. Liquid oxygen:
A. Is blue in colour
B. Looks like water
C. Is invisible like oxygen in the air
D. Is opaque

Answer 1

As we all know that liquid oxygen is basically the liquid form of dioxygen. It is also a strong oxidising agent and also known as the industrial gas. It is freely available in air and obtained by liquefying. In the first liquid-fueled rocket, it used an oxidizer.

Complete step by step answer:
1. Air is a mixture of gases like oxygen and nitrogen along with a little amount of carbon dioxide, water vapours etc.
2. Liquid oxygen is one of the most common cryogenic liquid oxidisers which is used in spacecraft rockets along with the liquid hydrogen, kerosene or methane.
3. Liquid oxygen is also known as LOX in industrial and commercial areas.
4. It is pale blue in colour and possesses a strong paramagnetic property because it has an unpaired electron which helps in absorbing light in the visible region mainly blue colour.

**Therefore the correct answer is (A).

Additional information:**
1. When it touches any material, it enhances the brittle nature of that substance.
2. It can be obtained by fractional distillation of the naturally found oxygen, in a cryogenic air separation plant.
3. It is used as an oxygen supplier in hospitals and in high altitude flights.
4. Six gases were known as permanent gases as they cannot be liquefied in early 1800s and these involve oxygen, hydrogen, nitrogen, carbon monoxide, methane and nitric oxide.

Note:
If liquid oxygen is inhaled by mistake, it can lead to oxygen toxicity and nitrogen narcosis and can damage the lungs. Cleaning the liquid oxygen systems is highly risky as any contaminants or other particles can result in ignition of gas. Liquid hydrogen is highly explosive and can result in hydrogen burns.