Question

Which of the following sets contain atomic numbers of only representative elements? \[ \begin{aligned} \text{I.} \quad & 3,\;33,\;53,\;87 \\ \text{II.} \quad & 2,\;10,\;22,\;36 \\ \text{III.} \quad & 9,\;35,\;51,\;88 \\ \text{IV.} \quad & 17,\;25,\;37,\;48 \end{aligned} \] The correct answer is

• A. I \& II only
• B. II \& III only
• C. I \& III only
• D. II \& IV only \bigskip

Hint:

Representative elements include only: \begin{itemize} \item \(s\)-block (Groups 1 and 2) \item \(p\)-block (Groups 13--18) \end{itemize} They do \textbf{not} include transition (\(d\)-block) or inner transition (\(f\)-block) elements.

Answer 1

The Correct Option is C

Concept: Representative elements are the \(s\)-block and \(p\)-block elements of the periodic table (Groups 1, 2 and 13--18). Transition (\(d\)-block) and inner transition (\(f\)-block) elements are not representative elements.

Step 1: Examine each set.
• Set I: \(3\) (Li), \(33\) (As), \(53\) (I), \(87\) (Fr)
All are \(s\)- or \(p\)-block elements. \checkmark
• Set II: \(2\) (He), \(10\) (Ne), \(22\) (Ti), \(36\) (Kr)
Titanium (\(22\)) is a \(d\)-block element. \(\times\)
• Set III: \(9\) (F), \(35\) (Br), \(51\) (Sb), \(88\) (Ra)
All are representative (\(p\)-block and \(s\)-block) elements. \checkmark
• Set IV: \(17\) (Cl), \(25\) (Mn), \(37\) (Rb), \(48\) (Cd)
Manganese (\(25\)) and Cadmium (\(48\)) are \(d\)-block elements. \(\times\)

Step 2: Identify the correct sets. Only Sets I and III contain representative elements exclusively.

Step 3: Final conclusion. \[ \boxed{\text{I \& III only}} \] Hence, the correct option is \(\boxed{(C)}\).