JEE Main: Acidic Oxides + Primary Valency Trick | Inorganic Combo Question 💥
❓ Question ‘ X ’ is the number of acidic oxides among: VO₂, V₂O₃, CrO₃, V₂O₅, Mn₂O₇ . The primary valency of cobalt in the complex [ C o ( H 2 N C H 2 C H 2 N H 2 ) 3 ] 2 ( S O 4 ) 3 [ \mathrm{Co}(\mathrm{H_2NCH_2CH_2NH_2})_3 ]_2(\mathrm{SO_4})_3 (i.e. [ C o ( en ) 3 ] 2 ( S O 4 ) 3 [Co(\text{en})_3]_2(SO_4)_3 ) is ‘ Y ’. Find the value of X + Y . 🖼️ Question Image ✍️ Short Solution We solve in two parts — first count acidic oxides (X), then find the primary valency (Y). 🔹 Part A — Identify acidic oxides (find X) For each oxide determine the oxidation state of the metal and typical acid/base character: VO₂ — V oxidation state: +4. Oxides of transition metals at intermediate oxidation states (like +2, +3, +4) are typically basic or amphoteric , not strongly acidic. VO₂ is amphoteric/neutral → not counted as acidic. V₂O₃ — V oxidation state: +3. Lower oxidation oxides are generally basic (or amphoteric) → not acidic . CrO₃ — Cr oxidation state: +...