List of top Chemistry Questions on Qualitative Analysis asked in JEE Advanced

During sodium nitroprusside test of sulphide ion in an aqueous solution, one of the ligands coordinated to the metal ion is converted to

The monomer (X) involved in the synthesis of Nylon 6,6 gives positive carbylamine test. If 10 moles of X are analyzed using Dumas method, the amount (in grams) of nitrogen gas evolved is ____. Use: Atomic mass of N (in amu) = 14

The correct match of the group reagents in List-I for precipitating the metal ion given in List-II from solutions is:

List-IList-II
(P) Passing H2S in the presence of NH4OH(1) Cu2+
(Q) (NH4)2CO3 in the presence of NH4OH(2) Al3+
(R) NH4OH in the presence of NH4Cl(3) Mn2+
(S) Passing H2S in the presence of dilute HCl(4) Ba2+
(5) Mg2+

When potassium iodide is added to an aqueous solution of potassium ferricyanide, a reversible reaction is observed in which a complex P is formed. In a strong acidic medium, the equilibrium shifts completely towards P. Addition of zinc chloride to P in a slightly acidic medium results in a sparingly soluble complex Q.
The number of zinc ions present in the molecular formula of \( Q \) is:

Among \([Co(CN)_4]^{4-}\), \([Co(CO)_3(NO)]\), \(XeF_4\), \([PCl_4]^+\), \([PdCl_4]^{2-}\), \([ICl_4]^-\), \([Cu(CN)_4]^{3-}\), and \(P_4\), the total number of species with tetrahedral geometry is:
For a double-strand DNA, one strand is given below: The amount of energy required to split the double-strand DNA into two single strands is . kcal mol........\(^{-1}\). [Given: Average energy per H-bond for A-T base pair = 1 kcal mol\(^{-1}\), G-C base pair = 1.5 kcal mol\(^{-1}\), and A-U base pair = 1.25 kcal mol\(^{-1}\). Ignore electrostatic repulsion between the phosphate groups]
A sample initially contains only U-238 isotope of uranium. With time, some of the U-238 radioactively decays into Pb-206 while the rest remains undisintegrated. When the age of the sample is \( P \times 10^8 \) years, the ratio of the mass of Pb-206 to that of U-238 in the sample is found to be 7. The value of \( P \) is: \[ \text{[Given: Half-life of U-238 = \(4.5 \times 10^9\) years; \(\log_e2 = 0.693\)]} \]
In the following reaction sequence, the major product \(Q\) is:
To form a complete monolayer of acetic acid on 1 g of charcoal, 100 mL of 0.5 M acetic acid was used. Some of the acetic acid remained unadsorbed. To neutralize the unadsorbed acetic acid, 40 mL of 1 M NaOH solution was required. If each molecule of acetic acid occupies \(P \times 10^{-23} \, m^2\) surface area on charcoal, the value of \(P\) is \_\_\_\_\_. \text{[Use given data: Surface area of charcoal} = 1.5 \times 10^{2} \text{ m}^{2}\text{g}^{-1}; \text{Avogadro's number (N}_{\text{A}}) = 6.0 \times 10^{23} \text{mol}^{-1}]
The species formed on fluorination of phosphorus pentachloride in a polar organic solvent are:
The option(s) with the correct sequence of reagents for the conversion of P to Q is (are):
The compound(s) having peroxide linkage is (are):
A mixture of two salts is used to prepare a solution S, which gives the following results:

\(\text{White precipitate(s) only} \underset{\text{Room temperature}}{\overset{\text{Dilute NaOH(aq)}}{\longleftarrow}} \text{S (aq solution of the salts)}\underset{\text{Room temperature}}{\overset{\text{Dilute HCl(aq)}}{\longrightarrow}} \text{White precipitate(s) only}\)
The correct option(s) for the salt mixture is(are)