List of top Chemistry Questions asked in JEE Main

Consider the following organic reaction sequence. Choose the final product (X) from the following (consider the major product in all intermediate reactions).

Consider the following reactions. Total number of electrons in the \(\pi\)-bonds and lone pair of electrons in the product (X) is :}

The correct order of first \((\Delta_iH_1)\) and second \((\Delta_iH_2)\) ionisation enthalpy values of Cr and Mn are:}

• [A.] \( \Delta_iH_1: Cr>Mn \)
• [B.] \( \Delta_iH_2: Cr>Mn \)
• [C.] \( \Delta_iH_1: Mn>Cr \)
• [D.] \( \Delta_iH_2: Mn>Cr \)

Choose the correct answer.

An optically active alkyl bromide \(C_4H_9Br\) reacts with ethanolic KOH to form major compound [A] which reacts with bromine to give compound [B]. Compound [B] reacts with ethanolic KOH and sodamide to give compound [C]. One molecule of water adds to compound [C] on warming with mercuric sulphate and dilute sulphuric acid at \(333\,K\) to form compound [D]. The functional group in compound D is confirmed by :

\(X\) is the product obtained by hydrolysis of prop-1-yne in the presence of mercuric sulphate under dilute acidic medium. \(Y\) is obtained by the reaction of ethanenitrile with methyl magnesium bromide in dry ether followed by hydrolysis. IUPAC name of product obtained from \(X\) and \(Y\) in presence of barium hydroxide followed by heating is :

Given below are two statements:} Statement I:} A mixture of \(C_{12}H_{22}O_{11}\) (sugar) and \(NaCl\) can be separated by dissolving sugar in alcohol, due to differential solubility. Statement II:} Rose essence from rose petals is separated by steam distillation due to its high volatility and insolubility in \(H_2O\). Choose the correct answer.

Which of the following sequences of hybridisation, geometry and magnetic nature are correct for the given coordination compounds?}

• [A.] \([NiCl_4]^{2-}\) -- \(sp^3\), tetrahedral, paramagnetic
• [B.] \([Ni(NH_3)_6]^{2+}\) -- \(sp^3d^2\), octahedral, paramagnetic
• [C.] \([Ni(CO)_4]\) -- \(sp^3\), tetrahedral, paramagnetic
• [D.] \([Ni(CN)_4]^{2-}\) -- \(dsp^2\), square planar, diamagnetic

Choose the correct answer.

Match List-I with List-II.

Choose the correct answer.

Given is a concentrated solution of a weak electrolyte \(A_xB_y\) of concentration \(c\) and dissociation constant \(K\). The degree of dissociation is given by:

Given below are two statements:} A semipermeable membrane separates two chambers:

Statement I:} \(H_2O\) molecules move from chamber 1 to chamber 2. Statement II:} The osmotic pressure of a solution prepared by dissolving \(50\,\text{mg}\) of potassium sulphate \((\text{molar mass}=174\,\text{g mol}^{-1})\) in \(2\,\text{L}\) of water (at \(27^\circ\text{C}\)) is \(0.0107\,\text{bar}\). \((R=0.083\,\text{dm}^3\text{bar K}^{-1}\text{mol}^{-1})\) Choose the correct answer.

In a period, the first ionisation enthalpy of the element at extreme left and the negative electron gain enthalpy of the extreme right element, except noble gases, are respectively.

For a general redox reaction} \[ \text{Anode: } \text{Red}_1 \rightarrow \text{Ox}_1^{n_1+} + n_1e^- \] \[ \text{Cathode: } \text{Ox}_2 + n_2e^- \rightarrow \text{Red}_2^{n_2-} \] Which of the following statement is incorrect?

Given below are two statements:} Statement I:} The number of compounds among \(SO_2, SO_3, SF_4, SF_6\) and \(H_2S\) in which sulphur does not obey the octet rule is \(3\). Statement II:} Among \(H_2O, ClF_5, SF_4, [NH_3BF_3], [BrF_5Cl], ClF_3, XeF_4\) and \([XeF_4, ClF_3(H_2O)]\), the number of sets in which the molecules have one lone pair of electrons on the central atom is \(1\). Choose the correct answer.

Which of the following contain the same number of atoms? (Given : Molar mass in g mol\(^{-1}\) of H, He, O and S are \(1,4,16\) and \(32\) respectively)}

• [A.] \(2\,\text{g}\) of \(O_2\) gas
• [B.] \(4\,\text{g}\) of \(SO_2\) gas
• [C.] \(1400\,\text{mL}\) of \(O_2\) at STP
• [D.] \(0.05\,\text{L}\) of He at STP
• [E.] \(0.0625\,\text{mol}\) of \(H_2\) gas

Choose the correct answer from the options given below:

The Bohr radius of a hydrogen like species is \(70.53\,\text{pm}\). The species and the stationary state \((n)\) are respectively. (Given: Hydrogen atom Bohr radius is \(52.9\,\text{pm}\)).

At 298 K, the molar conductivity of $x% \ (w/w)$ MX solution (aqueous) is 123.5 S cm$^2$ mol$^{-1}$. The conductance of same solution is $1.9 \times 10^{-3}$ S. The value of $x$ is ______ $\times 10^{-2}$.
(Given : cell constant $= 1.3 \text{ cm}^{-1}$; molar mass of MX is 75 g mol$^{-1}$, density of aqueous solution of MX at 298 K is 1.0 g mL$^{-1}$)}

For a reaction $A \to P$ at $T$ K, the half life ($t_{1/2}$) is plotted as a function of initial concentration $[A]_o$ of A as given below. The value of $x$ in the given figure is ______ s (Nearest integer)}

20 g hemoglobin in a 1 L aqueous solution (A) at 300 K is separated from pure water by semi permeable membrane. At equilibrium the height of solution in a tube dipped in a solution (A) is found to be 80.0 mm higher than the tube dipped in water. The molar mass of hemoglobin is ______ kg mol$^{-1}$. (Nearest integer)
(Given : $g=10 \text{ m s}^{-2}$, $R=8.3 \text{ kPa dm}^3 \text{ K}^{-1}\text{mol}^{-1}$, density of solution $= 1000 \text{ kg m}^{-3}$)}

Given below are two statements :
Statement I : Heating benzamide with bromine in an ethanolic solution of sodium hydroxide will give benzylamine.
Statement II : Nitration of aniline with $HNO_3/H_2SO_4$ at 288 K produces m-nitroaniline in higher amount than o-nitroaniline (pH adjusted).
In the light of the above statements, choose the correct answer from the options given below :

A paper dipped in a dil. $H_2SO_4$ solution of 'X' upon treatment with $SO_2$ gas turns into green. The compound 'X' is :

The total number of unpaired electrons present in the $d^3$, $d^4$ (low spin), $d^5$ (high spin), $d^6$ (high spin) and $d^7$ (low spin) octahedral complex systems is ______.

Given below are two statements :
Statement I :

$\alpha$ and $\beta$ D-(+)-glucose are two anomers of D-(+)-glucose.
Statement II : The open chain forms of D-glucose and D-fructose contain three similar chiral carbons at $C_3, C_4$ and $C_5$.
In the light of the above statements, choose the correct answer from the options given below :}

Identify the incorrect statement about tertiary structure of proteins.

RMgI when treated with ice cold water liberated a gas which occupied 1.4 dm$^3$/g at STP. The gas produced is further reacted with iodine in presence of $HIO_3$ to give compound (X). Compound (X) in presence of Na and dry ether produced compound (Y). Molar mass of compound (Y) is ______ g mol$^{-1}$. (Nearest integer)}