Its atomic number is 2
It is lighter than air
It is one of the constitutents of water
It is a noble gas
Answer is Right!
Answer is Wrong!
The correct answer is: B. It is lighter than air.
Helium is a gas that is lighter than air. This means that it will float in air. Balloons are filled with helium so that they will float.
The other options are incorrect.
- Option A is incorrect because the atomic number of helium is 2. This is not the reason why helium is used in balloons.
- Option C is incorrect because helium is not one of the constituents of water. Water is made up of hydrogen and oxygen.
- Option D is incorrect because helium is a noble gas. Noble gases are gases that are not very reactive. This is not the reason why helium is used in balloons.