Principles Related to Practical Chemistry questions
Questions are transcribed from NTA's official question paper. Diagrams are described in words; open the official PDF to see them. Every answer was solved twice independently and is shown only when both agree. Where they did not, we say so.
A salt with few drops of conc. HCl gives apple green colour in flame test. The group precipitate of the salt is dissolved in acetic acid and treated with $K_2CrO_4$ to give yellow precipitate. When the sodium carbonate extract of the salt solution is heated with conc. $HNO_3$ and ammonium molybdate, it resulted a canary yellow precipitate. The cation and anion present in the salt are respectively,
(1) $Ca^{2+}$ and $SO_4^{2-}$
(2) $Ba^{2+}$ and $PO_4^{3-}$
(3) $Mn^{2+}$ and $PO_4^{3-}$
(4) $Ba^{2+}$ and $SO_4^{2-}$
Show answer and solution
Answer: Option (2)
Key idea: Qualitative Analysis - Cation and Anion Identification through Flame Test, Group Precipitation, and Specific Anion Tests
**Flame Test Analysis:** Apple green flame with conc. HCl indicates $Ba^{2+}$ cation (characteristic color for barium)
**Confirmation of Cation:** Group precipitate + acetic acid + $K_2CrO_4$ gives yellow precipitate of $BaCrO_4$, confirming $Ba^{2+}$
**Anion Test:** Sodium carbonate extract converts the salt to soluble form for anion testing
**Phosphate Test:** Heating with conc. $HNO_3$ + ammonium molybdate gives canary yellow precipitate of $(NH_4)_3[PO_4 \cdot 12MoO_3]$
**Conclusion:** The canary yellow precipitate is specific for $PO_4^{3-}$ anion. Therefore, cation = $Ba^{2+}$ and anion = $PO_4^{3-}$
Given below are two statements:
**Statement I:** Sodium dichromate and potassium dichromate are classified as primary standards in titrimetric analysis.
**Statement II:** Phenolphthalein is a weak base, therefore it dissociates in acidic medium.
In the light of the above statements, choose the *correct* answer from the options given below
(1) Both Statement I and Statement II are true
(2) Both Statement I and Statement II are false
(3) Statement I is true but Statement II is false
(4) Statement I is false but Statement II is true
Show answer and solution
Answer: Option (2)
Key idea: Primary standards in titrimetry and acid-base indicators
**Statement I Analysis:** For primary standards, substances must be stable, non-hygroscopic, and of high purity.
Sodium dichromate ($Na_2Cr_2O_7 \cdot 2H_2O$) is hygroscopic and NOT a primary standard.
Potassium dichromate ($K_2Cr_2O_7$) is non-hygroscopic and IS a primary standard. Statement I is **false**.
**Statement II Analysis:** Phenolphthalein is a weak **acid**, not a weak base.
Phenolphthalein dissociates (ionizes) in **basic medium** (pH > 8.2), not acidic medium, giving pink color.
In acidic medium, phenolphthalein remains undissociated and colorless. Statement II is **false**.
Both statements are false, so the answer is option **(2)**.
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How many questions come from Principles Related to Practical Chemistry in JEE Main?
In the 9 shifts of JEE Main 2026 Session 2 we found 2 questions on it, about 0.2 per shift.
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On this page, with solutions. For more, use NTA Abhyas and our free mock tests.
