The passage represents a qualitative analysis flow diagram: (I) [Yellow ppt.] (A) [Gives blue colour — p Block Elements Chemistry Question
Question
The passage represents a qualitative analysis flow diagram: (I) [Yellow ppt.] $\xleftarrow{\text{K}_2\text{CrO}_4}$ (A) [Gives blue colour to the flame] $\xrightarrow{\Delta}$ (B) [Brown Gas] $\xrightarrow{\text{Gas (H), Very low temp.}}$ (C) [Blue colour liquid] $\xrightarrow{\text{H}_2\text{O}}$ (D) (A) $\xrightarrow{\text{H}_2\text{S}}$ (F) [Black ppt.] $\xrightarrow{\text{dil. HNO}_3}$ (G) [Vapour] + (H) [Gas] (H) $\xrightarrow{\text{FeSO}_4 + \text{H}_2\text{SO}_4}$ (E) [Complex compound]
💡 Solution & Explanation
Step 1: Borax is sodium tetraborate decahydrate (Na2B4O7.10H2O). Step 2: Adding a mineral acid (such as HCl or H2SO4) to an aqueous solution of borax results in an acid-base neutralization reaction: Na2B4O7 + 2HCl + 5H2O -> 2NaCl + 4H3BO3. Step 3: The product H3BO3 is orthoboric acid (also simply called boric acid), which precipitates out of the solution, matching option (b).