Question
Elements $$X, Y$$ and $$Z$$ have atomic numbers 19, 37 and 55 respectively. Which of the following statements is true about them?
A.
Their ionization potential would increase with increasing atomic number.
B.
$$Y$$ would have an ionization potential between those of $$X$$ and $$Z.$$
C.
$$Z$$ would have the highest ionization potential.
D.
$$Y$$ would have the highest ionization potential.
Answer :
$$Y$$ would have an ionization potential between those of $$X$$ and $$Z.$$
Solution :
Elements $$X, Y$$ and $$Z$$ with atomic numbers 19, 37, 55 lie in group 1 ( alkali metals ). Within a group, $$IE$$ decreases from top to bottom. Therefore, $$IE$$ of $$Y$$ could be between those of $$X$$ and $$Z.$$