Q.Give the similarities and differences in elements of 3d, 4d and 5d series.

Step 1. Similarities (Section 8.8). Elements of the 3d, 4d and 5d series broadly share the same physical properties -- lustrous, hard, high density, high melting/boiling points, good electrical/thermal conductors, high tensile strength, malleable, able to form alloys, often paramagnetic, and generally efficient catalysts -- and the same chemical properties -- electropositive, variable valency with coloured salts/complexes, good reducing agents, insoluble oxides/hydroxides, and several being biologically important (e.g. iron, cobalt, copper, molybdenum, zinc).

Step 2. The key documented difference. Although most of these properties are shared, the first (3d) row genuinely differs from the second (4d) and third (5d) rows specifically in how well it stabilises HIGH oxidation states. Molybdenum(V) and tungsten(VI) compounds are considerably more stable than the corresponding first-row chromium(VI) and manganese(VII) compounds. …

Direct recall of Section 8.8's shared property lists and its explicit statement of the one documented row-to-row …

• Listing only similarities or only the difference, when the question explicitly asks for both.
• Inventing additional 'differences' not actually stated in the chapter (e.g. guessing at colour or reactivit …