List of top Questions asked in JEE Main

On heating a mixture of common salt and $ K_2Cr_2O_7 $ in equal amount along with concentrated $ H_2SO_4 $ in a test tube, a gas is evolved. Formula of the gas evolved and oxidation state of the central metal atom in the gas respectively are :

Given below are two statements :
Statement I : The correct order in terms of atomic/ionic radii is $ Al>Mg>Mg^{2+}>Al^{3+} $.
Statement II : The correct order in terms of the magnitude of electron gain enthalpy is $ Cl>Br>S>O $.
In the light of the above statements, choose the correct answer from the options given below :

Consider the following spectral lines for atomic hydrogen :
A. First line of Paschen series
B. Second line of Balmer series
C. Third line of Paschen series
D. Fourth line of Bracket series
The correct arrangement of the above lines in ascending order of energy is :

Match List - I with List - II.

Choose the correct answer from the options given below :

Given below are two statements :
Statement I : The correct order in terms of bond dissociation enthalpy is $ Cl_2>Br_2>F_2>I_2 $.
Statement II : The correct trend in the covalent character of the metal halides is $ SnCl_2>SnCl_4 $, $ PbCl_2>PbCl_4 $ and $ UF_4>UF_6 $.
In the light of the above statements, choose the correct answer from the options given below :

Match List - I with List - II.

Choose the correct answer from the options given below :

Aqueous HCl reacts with $ MnO_2(s) $ to form $ MnCl_2(aq) $, $ Cl_2(g) $ and $ H_2O(l) $. What is the weight (in g) of $ Cl_2 $ liberated when 8.7 g of $ MnO_2(s) $ is reacted with excess aqueous HCl solution ?
(Given Molar mass in g mol$^{-1}$ : Mn = 55, Cl = 35.5, O = 16, H = 1)

The correct increasing order of C-H(A), C-O(B), C=O(C) and C$\equiv$N(D) bonds in terms of covalent bond length is :

The first and second ionization constants of $H_{2X}$ are $2.5 \times 10^{-8}$ and $1.0 \times 10^{-13}$ respectively. The concentration of $X^{2-}$ in $0.1$ M $H_{2}X$ solution is ____________$ \times 10^{-13}$ M. (Nearest Integer)

By usual analysis, 1.00 g of compound (X) gave 1.79 g of magnesium pyrophosphate. The percentage of phosphorus in compound (X) is : _________ (nearest integer)
(Given, molar mass in g mol$^{-1}$ ; O = 16, Mg = 24, P = 31)}

The osmotic pressure of a living cell is 12 atm at 300 K. The strength of sodium chloride solution that is isotonic with the living cell at this temperature is ____________ g L$^{-1}$. (Nearest integer)
Given: R = 0.08 L atm K$^{-1}$ mol$^{-1}$
Assume complete dissociation of NaCl
(Given : Molar mass of Na and Cl are 23 and 35.5 g mol$^{-1}$ respectively.)

The correct statements are :
A. Activation energy for enzyme catalysed hydrolysis of sucrose is lower than that of acid catalysed hydrolysis.
B. During denaturation, secondary and tertiary structures of a protein are destroyed but primary structure remains intact.
C. Nucleotides are joined together by glycosidic linkage between $ C_1 $ and $ C_4 $ carbons of the pentose sugar.
D. Quaternary structure of proteins represents overall folding of the polypeptide chain.
Choose the correct answer from the options given below :

Identify the metal ions among $Co^{2+}, Ni^{2+}, Fe^{2+}, V^{3+}$ and $Ti^{2+}$ having a spin-only magnetic moment value more than 3.0 BM. The sum of unpaired electrons present in the high spin octahedral complexes formed by those metal ions is ____________.

Given below are two statements :
Statement I : Crystal Field Stabilization Energy (CFSE) of $ [Cr(H_2O)_6]^{2}+ $ is greater than that of $ [Mn(H_2O)_6]^{2+} $.
Statement II : Potassium ferricyanide has a greater spin-only magnetic moment than sodium ferrocyanide.
In the light of the above statements, choose the correct answer from the options given below :}

A substance 'X' (1.5 g) dissolved in 150 g of a solvent 'Y' (molar mass = 300 g mol$^{-1}$) led to an elevation of the boiling point by 0.5 K. The relative lowering in the vapour pressure of the solvent 'Y' is $____________ $\times 10^{-2}$. (nearest integer)
[Given : $K_{b}$ of the solvent = 5.0 K kg mol$^{-1}$]
Assume the solution to be dilute and no association or dissociation of X takes place in solution.

MX is a sparingly soluble salt that follows the given solubility equilibrium at 298 K.
MX(s) $\rightleftharpoons M^{+(aq) }+ X^{-}(aq)$; $K_{sp} = 10^{-10}$
If the standard reduction potential for $M^{+}(aq) + e^{-} \rightarrow M(s)$ is $(E^{\circ}_{M^{+}/M}) = 0.79$ V, then the value of the standard reduction potential for the metal/metal insoluble salt electrode $E^{\circ}_{X^{-}/MX(s)/M}$ is ____________ mV. (nearest integer)
[Given : $\frac{2.303 RT}{F} = 0.059$ V]

Given below are four compounds :
(a) n-propyl chloride
(b) iso-propyl chloride
(c) sec-butyl chloride
(d) neo-pentyl chloride
Percentage of carbon in the one which exhibits optical isomerism is :

The sum of all the roots of the equation $(x-1)^2 - 5|x-1| + 6 = 0$, is:

Let the foci of a hyperbola coincide with the foci of the ellipse $\frac{x^2}{36} + \frac{y^2}{16} = 1$. If the eccentricity of the hyperbola is 5, then the length of its latus rectum is:

Let $(\alpha, \beta, \gamma)$ be the co-ordinates of the foot of the perpendicular drawn from the point (5, 4, 2) on the line $\vec{r}=(-\hat{i}+3\hat{j}+\hat{k})+\lambda(2\hat{i}+3\hat{j}-\hat{k})$. Then the length of the projection of the vector $\alpha\hat{i}+\beta\hat{j}+\gamma\hat{k}$ on the vector $6\hat{i}+2\hat{j}+3\hat{k}$ is:

The area of the region, inside the ellipse $x^2+4y^2=4$ and outside the region bounded by the curves $y=x-1$ and $y=1-x$, is:

Let PQ and MN be two straight lines touching the circle $x^2+y^2-4x-6y-3=0$ at the points A and B respectively. Let O be the centre of the circle and $\angle AOB = \pi/3$. Then the locus of the point of intersection of the lines PQ and MN is:

The value of $\text{cosec}10^\circ - \sqrt{3} \sec10^\circ$ is equal to:

Let $\vec{a} = -\hat{i} + 2\hat{j} + 2\hat{k}$, $\vec{b} = 8\hat{i} + 7\hat{j} - 3\hat{k}$ and $\vec{c}$ be a vector such that $\vec{a} \times \vec{c} = \vec{b}$. If $\vec{c} \cdot (\hat{i}+\hat{j}+\hat{k}) = 4$, then $|\vec{a}+\vec{c}|^2$ is equal to:

If the domain of the function $f(x) = \cos^{-1}\left(\frac{2x-5}{11-3x}\right) + \sin^{-1}(2x^2-3x+1)$ is the interval $[\alpha, \beta]$, then $\alpha + 2\beta$ is equal to:}