List of top Chemistry Questions asked in JEE Main

It is observed that characteristic $X$-ray spectra of elements show regularity When frequency to the power " $n$ " ie $v^n$ of $X$-rays emitted is plotted against atomic number " $Z$ ", following graph is obtained

The increasing order of metallic character

The wave function $(\Psi)$ of $2 s$ is given by $\Psi_{2 n }=\frac{1}{2 \sqrt{2 \pi}}\left(\frac{1}{a_0}\right)^{1 / 2}\left(2-\frac{r}{a_0}\right) e^{-\frac{r}{2 a_0}}$ At $r=r_0$, radial node is formed Thus, $r_0$ in terms of $a_0$

Given below are two statements: one is labeled as Assertion (A) and the other is labeled as Reason (R).
Statement-1: According to Bohr’s Model, angular momentum is Quantized for stationary orbits.
Statement-2: Bohr’s Model doesn’t follow Heisenberg’s Uncertainty Principle.
In the light of the above statements, write the detailed answer:

Number of compounds giving (i) red colouration with ceric ammonium nitrate and also (ii) positive iodoform test from the following is_____

The correct order of melting points of dichlorobenzenes is

$20 \,mL$ of $01 \,M \,NH _4 OH$ is mixed with $40\, mL$ of $005\, M \,HCl$ The $pH$ of the mixture is nearest to: (Given: $K _{ b }\left( NH _4 OH \right)=1 \times 10^{-5}, \log 2=030$, $\log 3=048, \log 5=069, \log 7=084$, $\log 11=104$ )

During the reaction of permanganate with thiosulphate, the change in oxidation of manganese occurs by value of 3. Identify which of the below medium will favour the reaction

Which one amongst the following are good oxidizing agents?
(A) $ \text{Sm}^{\text{2+}}$
(B) $\text{Ce}^{\text{2+}}$
(C)$ \text{Ce}^{\text{4+}}$
(D) $\text{Tb}^{\text{4+}}$
Choose the most appropriate answer from the options given below:

1 L, 0.02 M solution of [Co(NH₃)₅SO₄]Br is mixed with 1 L, 0.02 M solution of [Co(NH₃)₅Br]SO₄. The resulting solution is divided into two equal parts (X) and treated with excess of AgNO₃ solution and BaCl₂ solution respectively as shown below:
1 L Solution (X) + AgNO₃ solution (excess) → Y
1 L Solution (X) + BaCl₂ solution (excess) → Z
The number of moles of Y and Z respectively are

Some amount of dichloromethane $\left( CH _2 Cl _2\right)$ is added to $671.141 \,mL$ of chloroform $\left( CHCl _3\right)$ to prepare $2.6 \times 10^{-3} M$ solution of $CH _2 Cl _2$ (DCM) The concentration of DCM is ______$ppm$ (by mass) Given: atomic mass : $C =12$ $H =1$ $Cl =35.5$ density of $CHCl _3=1.49\, g \,cm ^{-3}$

The separation of two coloured substances was done by paper chromatography The distances travelled by solvent front, substance $A$ and substance $B$ from the base line are $3.25\, cm. 2.08 \, cm$ and $1.05\, cm$ respectively. The ratio of $R_f$ values of $A$ to $B$ is _______

Given below are two statements : one is labelled as Assertion A and the other is labelled as Reason $R$ :

Assertion (A) : Acetal / Ketal is stable in basic medium.

Reason (R) : The high leaving tendency of alkoxide ion gives the stability to acetal ketal in basic medium

In the light of the above statements, choose the correct answer from the options given below

How many bromo products are formed when ethane is reacted with excess of Br₂ on heating?

How many moles of Ba₃(PO₄)₂ will be formed by the reaction of 5 moles of BaCl₂ and 3 moles of Na₃(PO₄).

Which of the following statements is correct about freons?

Match List I with List II

Choose the correct answer from the options given below:

The dissociation constant of acetic acid is $x \times 10^{-5}$ When $25 \,mL$ of $0.2 \,M \,CH _3 COONa$ solution is mixed with $25 \,mL$ of $0.02\, M \,CH _3 COOH$ solution, the $pH$ of the resultant solution is found to be equal to 5. The value of $x$ is ___

The solubility product of BaSO₄ is $1 \times 10^{-10}$ at 298 K. The solubility of BaSO₄ in 0.1 M K₂SO₄(aq) is $x \times 10^{-9}$ g L⁻¹. Calculate the value of $x$.

For which of the following aqueous ion, spin only magnetic moment is 3.87 BM?

During the qualitative analysis of $SO _3^2$ using dilute $H _2 SO _4, SO _2$ gas is evolved which turns $K _2 Cr _2 O _7$ solution (acidified with dilute $H _2 SO _4$ ) :

Element not present in Nessler’s reagent is

The density of a monobasic strong acid (Molar mass $242 \,g$ mol) is $121 \,kg \,L$ The volume of its solution required for the complete neutralization of $25 \,mL$ of $024\, M\, NaOH$ is ___$\times 10^{-2} mL$ (Nearest integer)

The ratio of silica to alumina in cement is:

The geometry around boron in the product 'B' formed from the following reaction is $ BF _3+ NaH \xrightarrow{450 K } A + NaF$ $ A + NMe _3 \rightarrow B$

List I		List II
A		I	Fittig reaction
B		II	Wurtz Fittig reaction
C		III	Finkelstein reaction
D	\(C_{2}H_{5}CI + NaI \rightarrow C_{2}H_{5}I + NaCl\)	IV	Sandmeyer reaction