GENERAL KNOWLEDGE

Detailed explanation-1: -The elements which tend to have the tendency to lose electrons to form a positively charged element are known as metals. Lithium( ) is the lightest metal and solid present in the periodic table. Since the atomic number of Lithium is 3 it is also the third lightest element found on the earth.

Detailed explanation-2: -So from all above, the lightest metal is Lithium with atomic weight as 6.941 u, therefore option C is correct. Additional information:-Mercury is commonly known as quicksilver and was formerly known as hydrargyrum.

Detailed explanation-3: -Lithium is the lightest metal because it is placed in the first group of periodic tables (in alkali metal group) and it has the lowest atomic weight. We can also solve this problem by the concept of atomic number.