List of top Chemistry Questions asked in JEE Main

When borax is heated with CoO on a platinum loop, blue coloured bead formed is largely due to

White precipitate of \(AgCl\) dissolves in aqueous ammonia solution due to formation of:

Which of the following sets are correct regarding polymer?

1. Copolymer : Buna-S
2. Condensation polymer : Nylon-6,6
3. Fibres : Nylon-6,6
4. Thermosetting polymer : Terylene
5. Homopolymer : Buna-N

Choose the correct answer from given options below

Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason (R).
Assertion (A) : At 10°C, the density of a 5 M solution of KCl [atomic masses of K & Cl are 39 & 35.5 g \(mol^{–1}\) respectively], is ‘x’ g \(ml^{–1}\). The solution is cooled to –21°C. The molality of the solution will remain unchanged.
Reason (R) : The molality of a solution does not change with temperature as mass remains unaffected with temperature.
In the light of the above statements, choose the correct answer from the options given below.

Lithium nitrate and sodium nitrate, when heated separately, respectively, give :

The reaction of
 
with bromine and \(KOH\) gives \(RNH_2\) as the end product. Which one of the following is the intermediate product formed in this reaction?

Which one of the following is NOT a copolymer?

Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R.
Assertion A: Boric acid is a weak acid
Reason R: Boric acid is not able to release \(H^+\) ion on its own. It receives \(OH^–\) ion from water and releases \(H^+\) ion.
In the light of the above statements, choose the most appropriate answer from the options given below.

Stearic acid and polyethylene glycol react to form which one of the following soap/s detergents?

The number of radial and angular nodes in 4d orbital are, respectively

Number of electrophilic centres in the given compound is ____________.

In the cobalt-carbonyl complex : \(\mathrm{[Co_2(CO)_8]}\), number of Co-Co bonds is "X" and terminal CO ligands is "Y". X + Y = ____________.

The major product 'A' of the following given reaction has ____________ \(sp^2\) hybridized carbon atoms.
2,7-Dimethyl-2,6-octadiene \(\xrightarrow{H^+}\) A (Major Product)

Which one of the following elemental forms is not present in the enamel of the teeth?

Which of the following is an example of polyester?

The osmotic pressure of blood is 7.47 bar at 300 K. To inject glucose to a patient intravenously, it has to be isotonic with blood. The concentration of glucose solution in \(\mathrm{gL^{-1}}\) is ____________. (Molar mass of glucose = 180 g \(\mathrm{mol^{-1}}\), R = 0.083 L bar \(\mathrm{K^{-1}\,mol^{-1}}\)) (Nearest integer)

The rate constants for decomposition of acetaldehyde have been measured over the temperature range 700 - 1000 K. The data has been analysed by plotting ln k vs \(\dfrac{10^3}{T}\) graph. The value of activation energy for the reaction is ____________ \(\mathrm{kJ\,mol^{-1}}\). (Nearest integer)
(Given : R = 8.31 \(\mathrm{J\,K^{-1}\,mol^{-1}}\))

The cell potential for the following cell
\(\mathrm{Pt\,|\,H_2(g)\,|\,H^+(aq)\,||\,Cu^{2+}(0.01\ M)\,|\,Cu(s)}\)
is 0.576 V at 298 K. The pH of the solution is __________. (Nearest integer)
(Given : \(E^o_{\mathrm{Cu^{2+}/Cu}} = 0.34\) V and \(\dfrac{2.303\,RT}{F} = 0.06\) V)

The difference in oxidation state of chromium in chromate and dichromate salts is ____________.

Which of the following is not a broad spectrum antibiotic?

Which of the following statements are correct?
(A) Both \(\mathrm{LiCl}\) and \(\mathrm{MgCl_2}\) are soluble in ethanol.
(B) The oxides \(\mathrm{Li_2O}\) and \(\mathrm{MgO}\) combine with excess of oxygen to give superoxide.
(C) \(\mathrm{LiF}\) is less soluble in water than other alkali metal fluorides.
(D) \(\mathrm{Li_2O}\) is more soluble in water than other alkali metal oxides.
Choose the most appropriate answer from the options given below :

Identify the correct statement for \(\mathrm{B_2H_6}\) from those given below :
(A) In \(\mathrm{B_2H_6}\), all B-H bonds are equivalent.
(B) In \(\mathrm{B_2H_6}\), there are four 3-centre-2-electron bonds.
(C) \(\mathrm{B_2H_6}\) is a Lewis acid.
(D) \(\mathrm{B_2H_6}\) can be synthesized from both \(\mathrm{BF_3}\) and \(\mathrm{NaBH_4}\).
(E) \(\mathrm{B_2H_6}\) is a planar molecule.
Choose the most appropriate answer from the options given below :

During the qualitative analysis of salt with cation y²⁺, addition of a reagent (X) to alkaline solution of the salt gives a bright red precipitate. The reagent (X) and the cation (y²⁺) present respectively are :

The highest industrial consumption of molecular hydrogen is to produce compounds of element :