Question

Elements ${}^{\prime }{X}^{\prime }{,}^{\prime }{Y}^{\prime }$ and ${}^{\prime }{Z}^{\prime }$ have atomic numbers $19,37$ and $55$ respectively. Which of the following statements is false about them?

• A. Their ionization potential would increase with increasing atomic number
• B. ${}^{\prime }{Y}^{\prime }$ would have an ionization potential between those of ${}^{\prime }{X}^{\prime }$ and ${}^{\prime }{Z}^{\prime }$
• C. ${}^{\prime }{Z}^{\prime }$ would have the highest ionization potential
• D. ${}^{\prime }{Y}^{\prime }$ would have the highest ionization potential

Answer 1

The correct option is D ${}^{\prime }{Y}^{\prime }$ would have the highest ionization potential

As the atomic numbers are $193755$ we can see the elements are at a gap of $18$ elements $(\therefore K,Rb,Cs)$. Which means they are from three consecutive periods of same group. Thus, on moving down as ionic radii increases ionisation potential increases. So, from $X⟶Z$ ionisation potential will decrease. Thus the false statements are $A$,$B$ and $C$.