Q55 / 180 · KCET 2022 · Chemistry

Elements $X, Y$ and $Z$ have atomic numbers 19,37 and 55 respectively. Which of the following statements is true about them ?

  • Correct answer
    A
    $Y$ would have an ionisation potential between those of $X$ and $Z$.
  • B
    $Z$ would have the highest ionisation potential.
  • C
    $Y$ would have the highest ionisation potential.
  • D
    Their ionisation potential would increase with increasing atomic number.

Solution

Elements $X, Y$ and $Z$ with atomic number 19 , 37 and 55 respectively $\mathrm{K}, \mathrm{Pb}$ and $\mathrm{Cs}$. These elements are belongs to group-I of periodic table. On moving down the period in group-l ionisation potential will decrease down the group. Thus, the order is $X>Y>Z$. Therefore, statement $(a)$ is correct.

Hence, the correct answer is option: 'A'.

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