Question

The lightest element in the periodic table is _________________.
A.Lithium
B.Fluorine
C.Hydrogen
D.Helium

Answer 1

Hint: The elements placed early in the periodic table are generally the lightest while those placed last are the one with high atomic weights. Atomic mass increases along with atomic number.

Complete Stepwise Solution:
The Mendeleev’s periodic law placed the elements in the periodic table based on their increasing atomic weights. As per that classification, the lightest element of the periodic table is hydrogen.
Hydrogen is not only the lightest element in the periodic table, it is the lightest element of the entire universe.

Hence, the correct answer is option C.

Notes: With atomic number 1 and atomic weight 1, hydrogen being the lightest element in the periodic table and not only that due to its light weight and small size, it can take part in a number of reactions due to which this element is found in almost all the components and compounds in this universe.
Due to the light-weight nature hydrogen gas was used to fill the air balloons and also the hot –air balloons. But the use has been discontinued due to their highly combustible nature.
Hydrogen is also used for different other applications such as the follows:
- Used in different industrial sectors for the manufacture of different chemicals such as ammonia by the Haber-Bosch process.
- It is also used to carry out different processes in the metallurgical industry, the textile industry, glass making, and electronics.
- It is used in fuel cells and also as fuel for rocket launching.