Radiation Safety Practice Exam

Which element is represented by the symbol 'He'?

1. Helium

2. Hydrogen

3. Hafnium

4. Holmium

The correct answer is: Helium

The symbol 'He' corresponds to the element helium, which is a colorless, odorless, and inert gas. Helium is the second lightest and second most abundant element in the observable universe, primarily produced by stellar nuclear fusion processes. This noble gas has unique properties, such as being non-reactive due to its full outer electron shell, making it less likely to form compounds with other elements. Helium is commonly used in various applications, including filling balloons, as a cryogenic coolant in certain types of nuclear reactors, and in medical applications such as MRI machines. Its low boiling point and low density also make it valuable in scientific research and as a lifting gas. Understanding the periodic table symbols and the elements they represent is fundamental in chemistry and physics, as it allows for clear and concise communication about the different substances and their properties.