Question

Which of the following element had a controversial placement in modern periodic table?

• A. Helium
• B. Silicon
• C. Hydrogen
• D. Carbon

Answer 1

The correct option is C Hydrogen

Hydrogen can gain one electron and can become ${\text{H}}^{-}$ ion just like halogens (group 17) form ${\text{X}}^{-}$ ion. Also, it can lose an electron and can become ${\text{H}}^{+}$ ion just like alkali metals (group 1) form ${\text{M}}^{+}$ ion. Hence, the position of hydrogen was controversial in the modern periodic table although it is considered as a non-metal.