Question

Hydrogen gas is lighter than air.
A. True
B. False

Answer 1

Hint: To answer the question we should note that helium is present just after the hydrogen in periodic table and helium is used to fill balloons that float in air.

Step by step answer:
To check the statement present in the question, we should first discuss helium. Helium is the element which is present just after hydrogen in the periodic table. Hydrogen and helium are present on two different corners of the periodic table. Hydrogen is present on the left corner and helium is present on the right corner. We should know that there are very few similarities between hydrogen and helium. They are both colourless gases (in ordinary conditions) with very low boiling and melting points. They are both low-weight and non-metallic. Their low weight is so low that they are both lighter than air.
We use helium to fill balloons. We should know that helium is lighter than air. If we take the same volume of air and helium and weight them on a scale, the helium will weigh less. This is because helium is less dense. Because helium is lighter than air, a helium balloon rises. And hydrogen is another gas lighter than air; it is even lighter than helium. Hydrogen is not used in balloons because it is highly inflammable. When we put a match near a hydrogen-filled balloon, a real explosion takes place. This is because hydrogen burns very easily. It combines with oxygen to make water vapour.
So, we took helium as a reference in determining hydrogen weight. We came to know that helium is lighter than air, so it is used in balloons. But hydrogen is even lighter than helium and lighter than air.
So, from the above discussion we can say that the statement represented in the question is true. It is true that hydrogen gas is lighter than air.

Note: We should know that hydrogen is used as a fuel. Hydrogen fuel is a zero-emission fuel burned with oxygen. From recent times, we are using it in fuel cells or internal combustion engines. We also use them in commercial fuel cell vehicles, such as passenger cars, and have been used in fuel cell buses for many years. It is also used as a fuel for spacecraft propulsion.