Properties Of D Block Elements

Step 1: Concept
Potassium dichromate ( ) is a powerful oxidising agent in acidic media.
Step 2: Analysis
It accepts electrons: . It oxidises to .
Step 3: Conclusion
Its primary chemical use listed is as an oxidising agent.
Final Answer: (C)

Step 1: Relation
The de-Broglie wavelength is related to kinetic energy by: . This implies .
Step 2: Substitution
If the new kinetic energy , then the new wavelength .
Step 3: Ratio
.
Final Answer: (c)

Step 1: Identifying the behavior of low oxidation states in transition metals.
Transition metals with low oxidation states, such as or , tend to act as oxidizing agents. This is because they have the ability to easily donate electrons and thus oxidize other substances.

Step 2: Explanation of the options.
- (1) An oxidising agent: This is the correct answer. Low oxidation states in transition metals often serve as oxidizing agents.
- (2) A base: Transition metals with low oxidation states are less likely to act as bases.
- (3) An acid: Transition metals with low oxidation states are more commonly seen as oxidizing agents rather than acids.
- (4) None of these: This is incorrect because low oxidation states of transition metals indeed act as oxidizing agents.

Step 3: Conclusion.
The correct answer is (1) An oxidising agent.

Step 1: Identifying colored chlorides.
Among the given elements, cobalt forms a colored chloride due to the presence of unpaired electrons in its orbitals, which can absorb certain wavelengths of light.

Step 2: Explanation of the options.
- (1) Hg: Mercury chloride is not typically colored.
- (2) Ag: Silver chloride is a white solid, not colored.
- (3) Co: Cobalt chloride forms a blue color in its hydrated form, and a pink color in anhydrous form, due to the presence of unpaired electrons in the orbitals.
- (4) Zn: Zinc chloride is colorless and does not exhibit any color.

Step 3: Conclusion.
The correct answer is (3) Co.

Step 1: Formula / Definition}

Step 2: Calculation / Simplification}
The directly on the ring is to the ring ketone.
Heating eliminates this specific carboxyl group as .
The side chain remains intact.
Step 3: Final Answer

Step 1: Formula / Definition}

Step 2: Calculation / Simplification}
Acetyl = , N-propyl =
Structure:
Step 3: Final Answer

Concept: Some metals form metal-metal bonds resulting in dimeric ions.

Step 1: Mercury behavior
Mercury forms Hg ion (dimeric ion).

Step 2: Structure
Two Hg atoms are bonded together: Conclusion:
Thus, mercury forms dimeric ions.

Concept: Hydrogen peroxide forms peroxo complexes with transition metals.

Step 1: Reaction.
Dichromate reacts with H O in acidic medium.

Step 2: Product formed.
Blue coloured compound is peroxo complex CrO .

Step 3: Conclusion.
Correct answer is (B)

Concept: Magnetic moment ( ) depends on the number of unpaired electrons ( ): Higher the number of unpaired electrons, higher the magnetic moment.

Step 1: Determine electronic configurations and unpaired electrons.
• Zn : Atomic number 30. Zn: . Zn loses two 4s electrons → . Unpaired electrons = 0.
• Ti : Atomic number 22. Ti: . Ti loses two 4s electrons and one 3d electron → . Unpaired electrons = 1.
• Sc : Atomic number 21. Sc: . Sc loses two 4s electrons and one 3d electron → . Unpaired electrons = 0.
• Mn : Atomic number 25. Mn: . Mn loses two 4s electrons → . Unpaired electrons = 5 (half-filled d-subshell, highly stable).

Step 2: Compare magnetic moments. Mn has 5 unpaired electrons → highest magnetic moment.

Concept: Coinage metals (Cu, Ag, Au) belong to Group 11.

Step 1: Electronic configurations.

Step 2: General configuration.

Step 3: Reason. Filled subshell provides extra stability; one -electron available for bonding.

Concept: Structure of dichromate ion : - Each Cr atom is surrounded by 4 oxygen atoms in a tetrahedral arrangement - One oxygen atom acts as a bridge between the two Cr atoms - The other three oxygen atoms are terminal

Step 1: Analyze structure.
Each Cr is bonded to: - 3 terminal oxygen atoms (double bonded) - 1 bridging oxygen atom (single bonded)

Step 2: Count for one chromium.


Step 3: Conclusion.
Each Cr atom is directly attached to 4 oxygen atoms.

Concept: Colour in transition metal ions arises due to transitions, which occur only when the -orbital is partially filled (not or ).

Step 1: Electronic configurations:

Step 2: Number of coloured ions =