Top d and f Block Questions for NEET

The d and f block elements chapter is one of the most conceptual and moderately scoring sections in NEET Chemistry. Questions from this chapter are generally based on electronic configuration, oxidation states, color, magnetic properties, and lanthanide contraction. If you prepare the Top 5 d and f Block Questions, you can easily tackle most PYQs asked in NEET.

In this article, we will cover the Top 5 d and f Block Questions that are frequently asked or expected in NEET, along with clear explanations and exam-oriented tricks. Since most questions are NCERT-based, understanding these concepts properly will help you score efficiently.

Question 1: Electronic Configuration of Transition Elements

What is the electronic configuration of chromium (Cr) and copper (Cu), and why are they exceptional?

Detailed Explanation

According to the Aufbau principle, the expected configurations should be:

• Cr: $[Ar] \, 3d^4 4s^2$[Ar]3d44s2
• Cu: $[Ar] \, 3d^9 4s^2$[Ar]3d94s2

However, the actual configurations are:

• Cr: $[Ar] \, 3d^5 4s^1$[Ar]3d54s1
• Cu: $[Ar] \, 3d^{10} 4s^1$[Ar]3d104s1

This happens because half-filled and fully filled d-orbitals provide extra stability due to:

• Symmetrical distribution of electrons
• Minimum electron repulsion

Final Answer:

Cr = $[Ar] \, 3d^5 4s^1$[Ar]3d54s1, Cu = $[Ar] \, 3d^{10} 4s^1$[Ar]3d104s1

This is one of the most repeated concepts in the Top 5 d and f Block Questions.

Question 2: Variable Oxidation States

Why do transition elements show variable oxidation states?

Detailed Explanation

Transition elements have partially filled d-orbitals. The energy difference between ns and (n−1)d orbitals is very small.

Because of this:

• Both ns and d electrons can participate in bonding
• Different numbers of electrons can be lost

This leads to variable oxidation states.

For example:

• Iron (Fe): +2, +3
• Manganese (Mn): +2 to +7

Final Answer:

Transition elements show variable oxidation states due to involvement of both ns and (n−1)d electrons in bonding.

This is a very common theory-based question in the Top 5 d and f Block Questions.

Question 3: Color of Transition Metal Compounds

Why are most transition metal compounds colored?

Detailed Explanation

The color of transition metal compounds is due to d–d electronic transitions.

When light falls on a transition metal ion:

• Electrons absorb specific wavelengths
• They jump between d-orbitals
• The remaining light is observed as color

For example:

• $Cu^{2+}$Cu2+ appears blue
• $Fe^{3+}$Fe3+ appears yellow/brown

Final Answer:

Transition metal compounds are colored due to d–d transitions of electrons.

This concept is frequently tested in the Top 5 d and f Block Questions.

Question 4: Lanthanide Contraction

What is lanthanide contraction and its consequences?

Detailed Explanation

Lanthanide contraction refers to the gradual decrease in atomic and ionic radii of lanthanides from La to Lu.

Reason:

• Poor shielding effect of 4f electrons
• Increased effective nuclear charge

Consequences:

• Similar sizes of 4d and 5d elements
• Difficulty in separation of lanthanides
• Variation in basic strength of hydroxides

Final Answer:

Lanthanide contraction is the gradual decrease in size across the lanthanide series due to poor shielding by 4f electrons.

This is a very important concept in the Top 5 d and f Block Questions.

Question 5: Magnetic Properties

Calculate the number of unpaired electrons in $Fe^{3+}$Fe3+.

Detailed Explanation

Electronic configuration of Fe:$$[Ar] \, 3d^6 4s^2$$[Ar]3d64s2

For $Fe^{3+}$Fe3+:

• Remove 2 electrons from 4s and 1 from 3d

$$Fe^{3+} = [Ar] \, 3d^5$$Fe3+=[Ar]3d5

Number of unpaired electrons = 5

Final Answer:

5 unpaired electrons

This type of question is very common in the Top 5 d and f Block Questions.

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Why These Top 5 d and f Block Questions Are Important

The Top 5 d and f Block Questions cover the most expected areas in NEET. Questions are usually:

• Concept-based rather than lengthy
• Focused on electronic configuration and properties
• Derived directly from NCERT

By mastering these Top 5 d and f Block Questions, you can confidently solve most questions from this chapter.

Smart Preparation Strategy

To effectively prepare the Top 5 d and f Block Questions, follow these strategies:

Focus on electronic configurations and exceptions like Cr and Cu. Understand trends in oxidation states. Learn the reasons behind color and magnetic properties. Revise lanthanide contraction thoroughly.

Regular revision of these Top 5 d and f Block Questions will improve both speed and accuracy.

Common Mistakes to Avoid

While preparing the Top 5 d and f Block Questions, students often make mistakes like:

Ignoring exceptions in electronic configuration. Memorizing without understanding concepts. Confusing oxidation states and magnetic properties.

Avoiding these mistakes will help you score better in NEET.

FAQs on Top 5 d and f Block Questions

Is d and f block important for NEET?

Yes, it contributes 1–2 questions and is relatively easy if concepts are clear.

Are numerical questions asked from this chapter?

Mostly conceptual, but some numerical questions on magnetic moment are asked.

How to remember electronic configurations?

Practice regularly and focus on exceptions.

Is lanthanide contraction important?

Yes, it is one of the most frequently asked topics in the Top 5 d and f Block Questions.

Conclusion

The Top 5 d and f Block Questions discussed here cover the most important and expected concepts for NEET. From electronic configuration to magnetic properties, these topics are consistently tested.

By practicing these Top 5 d and f Block Questions, you can strengthen your understanding and score efficiently in NEET Chemistry.