JEE MainChemistryClassification of Elements and Periodicity in Properties
Four hypothetical elements P, Q, R, and S belong to groups g and g+1 , and periods p and p+1 of the p-block (excluding anomalous groups like 15/16 or 17/18). The order of their atomic radii is P The order of their first ionization enthalpies is S Which of the following correctly represents their positions in the periodic table?
Options
- APeriod p : P (Group g ), Q (Group g+1 ) Period p+1 : R (Group g ), S (Group g+1 )
- BPeriod p : S (Group g ), R (Group g+1 ) Period p+1 : Q (Group g ), P (Group g+1 )
- CPeriod p : Q (Group g ), P (Group g+1 ) Period p+1 : S (Group g ), R (Group g+1 )
- DPeriod p : R (Group g ), P (Group g+1 ) Period p+1 : S (Group g ), Q (Group g+1 )
Correct answer
C. Period p : Q (Group g ), P (Group g+1 ) Period p+1 : S (Group g ), R (Group g+1 )
Step-by-step solution
Atomic radius generally decreases across a period from left to right and increases down a group. First ionization enthalpy generally increases across a period and decreases down a group. Given the order of atomic radii is P Between the top-left element and the bottom-right element, the increase in size down a group is more significant than the decrease across a period. Therefore, the top-left element is smaller than the bottom-right element. This means Q is at the top-left and R is at the bottom-right. Thus, the po