An ion with mass number 56 contains 3 units of positive charge and 30.4% more neutrons than electrons. Assign the symbol to this ion.

Explanation

Suppose number of electrons in the ion, `M^(3+)=x`
`:.` Number of neutrons `=x+30.4/100x=1.304x`
Number of electrons in the neutral atom `=x+3`
`:.` Number of protons `=x+3`
Mass number=Number of protons+Number of neutrons
`56=x+3+1.304x`
or `2.304x=53` or `x=23`
`:.` Number of protons=Atomic no. `=x+3=23+3=26`
Hence, the symbol of the ion will be `._(26)^(56)Fe^(3+)`.