In qualitative test for identification of presence of phosphorous, the compound is heated with an oxidising agent. Which is further treated with nitric acid and ammonium molybdate respectively. The yellow coloured precipitate obtained is :
- Na$_3$PO$_4$.12MoO$_3$
- (NH$_4$)$_3$PO$_4$.12(NH$_4$)$_2$MoO$_4$
- (NH$_4$)$_3$PO$_4$.12MoO$_3$
- MoPO$_4$.21NH$_4$NO$_3$
The Correct Option is C
Solution and Explanation
In the qualitative analysis of phosphorus, the following reaction occurs:
\[ \text{PO}_4^{3-} \text{ or } \text{HPO}_4^{2-} + (\text{NH}_4)_2\text{MoO}_4 \xrightarrow{\text{H}^+} (\text{NH}_4)_3\text{PO}_4 \cdot 12\text{MoO}_3 \downarrow \]
The product, $(\text{NH}_4)_3\text{PO}_4 \cdot 12\text{MoO}_3$, is a canary yellow precipitate known as ammonium phosphomolybdate.
Top Questions on Qualitative Analysis
Match List I with List II:
Choose the correct answer from the options given below:- NEET (UG) - 2025
- Chemistry
- Qualitative Analysis
Among the following cations, the number of cations which will give characteristic precipitate in their identification tests with
\(K_4\)[Fe(CN)\(_6\)] is : \[ {Cu}^{2+}, \, {Fe}^{3+}, \, {Ba}^{2+}, \, {Ca}^{2+}, \, {NH}_4^+, \, {Mg}^{2+}, \, {Zn}^{2+} \]- JEE Main - 2025
- Chemistry
- Qualitative Analysis
- Given below are two statements:
Statement I: In Lassaigne's test, the covalent organic molecules are transformed into ionic compounds.
Statement II: The sodium fusion extract of an organic compound having N and S gives prussian blue colour with FeSO4 and Na4[Fe(CN)6].
In the light of the above statements, choose the correct answer from the options given below.- JEE Main - 2025
- Chemistry
- Qualitative Analysis
- 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]
- JEE Advanced - 2024
- Chemistry
- Qualitative Analysis
- 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; \(\log_e2 = 0.693\)]} \]
- JEE Advanced - 2024
- Chemistry
- Qualitative Analysis
Questions Asked in JEE Main exam
If the system of equations \[ x + 2y - 3z = 2, \quad 2x + \lambda y + 5z = 5, \quad 14x + 3y + \mu z = 33 \] has infinitely many solutions, then \( \lambda + \mu \) is equal to:}
- JEE Main - 2025
- Calculus
- An electric dipole of mass \( m \), charge \( q \), and length \( l \) is placed in a uniform electric field \( E = E_0 \hat{i} \). When the dipole is rotated slightly from its equilibrium position and released, the time period of its oscillations will be:
- JEE Main - 2025
- Electric Dipole
The equilibrium constant for decomposition of $ H_2O $ (g) $ H_2O(g) \rightleftharpoons H_2(g) + \frac{1}{2} O_2(g) \quad (\Delta G^\circ = 92.34 \, \text{kJ mol}^{-1}) $ is $ 8.0 \times 10^{-3} $ at 2300 K and total pressure at equilibrium is 1 bar. Under this condition, the degree of dissociation ($ \alpha $) of water is _____ $\times 10^{-2}$ (nearest integer value). [Assume $ \alpha $ is negligible with respect to 1]
- JEE Main - 2025
- Law Of Chemical Equilibrium And Equilibrium Constant
- The distance of the point \( P(1, 2, 3) \) from the plane \( 3x - 4y + 12z - 7 = 0 \) is:
- JEE Main - 2025
- Geometry and Vectors
- Two iron solid discs of negligible thickness have radii \( R_1 \) and \( R_2 \) and moment of inertia \( I_1 \) and \( I_2 \), respectively. For \( R_2 = 2R_1 \), the ratio of \( I_1 \) and \( I_2 \) would be \( \frac{1}{x} \), where \( x \) is:
- JEE Main - 2025
- System of Particles & Rotational Motion