D Block Elements

Step 1: Understand highest oxidation states.
The highest oxidation state of an element depends on the number of valence electrons available for bonding, especially with highly electronegative elements like oxygen or fluorine.

Step 2: Analyze manganese (Mn).
Manganese (Z = 25) has electronic configuration . It can show a maximum oxidation state of , as seen in compounds like .

Step 3: Analyze chlorine (Cl).
Chlorine (Z = 17) has electronic configuration . It can show a maximum oxidation state of , as seen in and .

Step 4: Check other elements.
Cr: Maximum oxidation state is .
V: Maximum oxidation state is .
S: Maximum oxidation state is .

Step 5: Conclusion.
Manganese and chlorine both exhibit the highest oxidation state of .

Step 1: Understanding the concept.
The colour of compounds formed by transition elements mainly depends on the presence of partially filled d-orbitals. If the d-orbitals are completely filled or completely empty, no d–d electronic transitions occur, resulting in colourless compounds.

Step 2: Electronic configuration analysis.
Zinc (Z = 30) has the electronic configuration . In the +2 oxidation state, zinc forms ions with configuration , which has a completely filled d-subshell.

Step 3: Analysis of options.
(A) Co (Z = 27): has partially filled d-orbitals, so its compounds are coloured.
(B) Zn (Z = 30): Correct — has a completely filled d-subshell, so its compounds are colourless.
(C) Cu (Z = 29): has an incomplete d-subshell and forms coloured compounds.
(D) Mn (Z = 25): has half-filled d-orbitals and forms coloured compounds.

Step 4: Conclusion.
Zinc forms colourless compounds in the +2 oxidation state due to the absence of d–d transitions.

Step 1: Understanding freezing point depression.
The depression in freezing point ( ) is the difference between the freezing point of the pure solvent and the freezing point of the solution. The formula for freezing point depression is: where is the freezing point of the solution, is the freezing point of the pure solvent, and is the depression in freezing point.

Step 2: Analyzing the options.
(A) T = T : This is incorrect. The relation is additive, not multiplicative.
(B) T = - T: This is incorrect. It does not correctly represent the relation between freezing point and depression.
(C) T = T - : This is incorrect. The freezing point depression is added to the pure solvent's freezing point.
(D) T = + T: Correct — This is the correct relation for freezing point depression.

Step 3: Conclusion.
The correct answer is (D) T = + T.

Step 1: Understanding the oxidation states.
Cerium (Ce) is a lanthanide element that exhibits oxidation states other than +3, including +4. The other elements listed (Gd, Lu, La) only exhibit the +3 oxidation state.
Step 2: Conclusion.
The correct answer is (A) Ce.

Concept:
Step 1: Calculate moles of solvent.
Step 2: Find moles of solute.
Step 3: Calculate molar mass.
Step 4: Conclusion. Closest answer =