JEE Advanced · Chemistry · 26. Aldehydes & Ketones

Paragraph I: An organic compound $\mathbf{P}$ with molecular formula $\mathrm{C}_9 \mathrm{H}_{18} \mathrm{O}_2$ decolorizes bromine water and also shows positive iodoform test. $\mathbf{P}$ on ozonolysis followed by treatment with $\mathrm{H}_2 \mathrm{O}_2$ gives $\mathbf{Q}$ and $\mathbf{R}$. While compound $\mathbf{Q}$ shows positive iodoform test, compound $\mathbf{R}$ does not give positive iodoform test. $\mathbf{Q}$ and $\mathbf{R}$ on oxidation with pyridinium chlorochromate (PCC) followed by heating give $\mathbf{S}$ and $\mathbf{T}$, respectively. Both $\mathbf{S}$ and $\mathbf{T}$ show positive iodoform test.
Complete copolymerization of 500 moles of $\mathbf{Q}$ and 500 moles of $\mathbf{R}$ gives one mole of a single acyclic copolymer $\mathbf{U}$.
[Given, atomic mass: $\mathrm{H}=1, \mathrm{C}=12, \mathrm{O}=16$]
Question: Sum of number of oxygen atoms in $\mathbf{S}$ and $\mathbf{T}$ is

A 2
B 6
C 8
D 10

Verified Solution

Answer & Solution

Correct Answer

(A) 2

Step-by-step Solution

Detailed explanation

$\mathrm{S} \& \mathrm{~T}$ shows + ve idoform test.
Total oxygen atoms present in $\mathrm{S}, \mathrm{T}$ are $=1+1=2$
Ans. $\Rightarrow 2$

Apply the relevant identity from the chapter and substitute the values established in the previous step, keeping the original constraint in view.

Use the simplified expression to isolate the unknown, then plug the result back into the question setup to confirm the working is internally consistent.

Cross-check against a boundary or limiting case. Both the dimensional balance and the qualitative behaviour at the extreme should agree with the candidate answer.

Combine the steps above to identify the correct option. The remaining choices each fail at least one of the consistency, dimensional, or boundary checks.

Same subject

For a reaction, $A ⇌ P$ , the plots of $[A] a n d [P]$ with time at temperatures $T_{1} a n d T_{2}$ are given below.

If $T_{2} > T_{1}$ , the correct statement(s) is (are)
(Assume $∆ H^{⊝} a n d ∆ S^{⊝}$ are independent of temperature and ratio of $\ln K a t T_{1} t o \ln K a t T_{2}$ is greater than $T_{2} / T_{1}$ . Here H, S , G and K are enthalpy, entropy, Gibbs energy and equilibrium constant, respectively.)

JEE Advanced 2018 Hard

The wave function, $\psi_{ n , 1, m_{ l }}$ is a mathematical function whose value depends upon spherical polar coordinates $( r , \theta, \phi)$ of the electron and characterized by the quantum numbers $n , 1$ and $m _{ l }$. Here $r$ is the distance from the nucleus, $\theta$ is colatitude and $\phi$ is azimuth. In the mathematical functions given in the Table, Z is the atomic number and $a_0$ is Bohr radius

Column 1	Column 2	Column 3
(I) 1s orbital	$\text {(i) } \psi_{ n , 1, m_1}$ $\propto\left(\frac{ Z }{ a _{ o }}\right)^{\frac{3}{2}} e ^{-\left(\frac{ Zr }{ e _{ o }}\right)}$	(P)
(II) 2s orbital	(ii) One radial node	(Q) Probability density at the nucleus $\propto \frac{1}{ a _{ o }^3}$.
(III) $2 p _{ z }$ orbital	$\text {(iii) } \psi_{ n }, 1, m_{ l }$ $\propto\left(\frac{ Z }{ a _{ o }}\right)^{\frac{5}{2}} re ^{-\left(\frac{ Zr }{2 a _{ o }}\right)} \cos \theta$	(R) Probability density is maximum at the nucleus.
(IV) $3 d_{ z }^2$ orbital	(iv) $x y$-plane is a nodal plane	(S) Energy needed to excite an electron from $n =2$ state to $n =4$ state is $\frac{27}{32}$ times the energy needed to excite are electron from $n =2$ state to $n =6$ state.

For $\text{He} ^{+}$ion, the only incorrect combination

JEE Advanced 2017 Hard

Match the reactions (in the given stoichiometry of the reactants) in List-I with one of their products given in List-II and choose the correct option.

List - I	List - II
(P) $P _2 O _3$ $+~3 H _2 O \rightarrow$	(1) $P ( O )\left( OCH _3\right)$ $Cl _2$
(Q) $P _4+3 NaOH$ $+~3 H _2 O \rightarrow$	(2) $H _3 PO _3$
(R) $PCl _5+ CH _3$ $COOH \rightarrow$	(3) $PH _3$
(S) $H _3 PO _2$ $+~2 H _2 O ~+$ $4 AgNO _3 \rightarrow$	(4) $POCL _3$
	(5) $H _3 PO _4$

JEE Advanced 2023 Medium

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List - I	List - II
(P) \(P _2 O _3\) \(+~3 H _2 O \rightarrow\)	(1) \(P ( O )\left( OCH _3\right)\) \(Cl _2\)
(Q) \(P _4+3 NaOH\) \(+~3 H _2 O \rightarrow\)	(2) \(H _3 PO _3\)
(R) \(PCl _5+ CH _3\) \(COOH \rightarrow\)	(3) \(PH _3\)
(S) \(H _3 PO _2\) \(+~2 H _2 O ~+\) \(4 AgNO _3 \rightarrow\)	(4) \(POCL _3\)
	(5) \(H _3 PO _4\)