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MCQEasyJEE 2025Modern Periodic Table

JEE Chemistry 2025 Question with Solution

CHEMISTRY SECTION-A

The element that does not belong to the same period of the remaining elements (modern periodic table) is:

  • A

    Palladium

  • B

    Iridium

  • C

    Osmium

  • D

    Platinum

Answer

Correct answer:A

Step-by-step solution

Standard Method

Given: The elements are Palladium, Iridium, Osmium, and Platinum.

Find: The element that does not belong to the same period as the remaining elements in the modern periodic table.

The question asks to identify the element that does not belong to the same period as the others in the modern periodic table.

  • Palladium (Pd): Palladium is in the 5th period and Group 10.
  • Iridium (Ir): Iridium belongs to the 6th period and Group 9.
  • Osmium (Os): Osmium is located in the 6th period and belongs to Group 8.
  • Platinum (Pt): Platinum is also in the 6th period and is found in Group 10.

From this analysis, Iridium, Osmium, and Platinum all belong to the 6th period, whereas Palladium belongs to the 5th period.

Therefore, the element that does not belong to the same period as the remaining elements is Palladium. The correct option is A.

Using Atomic Numbers

Given: The elements are Palladium (Pd), Iridium (Ir), Osmium (Os), and Platinum (Pt).

Find: Which element is not in the same period as the other three.

In the modern periodic table, elements are arranged in periods based on their atomic numbers.

  • Palladium (Pd): atomic number 4646, located in period 5.
  • Iridium (Ir): atomic number 7777, located in period 6.
  • Osmium (Os): atomic number 7676, located in period 6.
  • Platinum (Pt): atomic number 7878, located in period 6.

Thus, Iridium, Osmium, and Platinum are all in period 6, while Palladium is in period 5.

Therefore, the element that does not belong to the same period as the others is Palladium. The correct option is A.

Common mistakes

  • Confusing group with period. The question asks about the horizontal row, not the vertical column. Always check the period number of each element before comparing them.

  • Judging only by similarity of transition-metal names or positions near one another. Nearby placement does not guarantee the same period. Verify the actual period of Pd, Ir, Os, and Pt from the modern periodic table.

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