List of top Chemistry Questions asked in JEE Main

Given
(i) C (graphite) + \(\mathrm{O_2(g)} \to \mathrm{CO_2(g)}\); \(\Delta_rH^{\ominus} = x\ \mathrm{kJ\ mol^{-1}}\)
(ii) C (graphite) + \(\frac{1}{2}\mathrm{O_2(g)} \to \mathrm{CO(g)}\); \(\Delta_rH^{\ominus} = y\ \mathrm{kJ\ mol^{-1}}\)
(iii) CO(g) + \(\frac{1}{2}\mathrm{O_2(g)} \to \mathrm{CO_2(g)}\); \(\Delta_rH^{\ominus} = z\ \mathrm{kJ\ mol^{-1}}\)
Based on the above thermochemical equations, find out which one of the following algebraic relationships is correct?

The major product of the following reaction is –

(cyclopent-3-en-1-one treated with \(\mathrm{NaBH_4}\) in EtOH)

The aldehydes which will not form Grignard product with one equivalent Grignard reagents are -

(A) benzaldehyde; (B) 4-HO₂C-C₆H₄-CHO; (C) 4-H₃CO-C₆H₄-CHO; (D) 4-HOH₂C-C₆H₄-CHO

The major product in the following conversion is –

(4-methoxyphenyl)-CH=CH-CH₃ treated with HBr (excess), heat, gives ?

If the de Broglie wavelength of the electron in \(n^{th}\) Bohr orbit in a hydrogenic atom is equal to \(1.5\pi a_0\) (\(a_0\) is Bohr radius), then the value of \(n/z\) is -

The element that does NOT show catenation is :

The molecule that has minimum /no role in the formation of photochemical smog, is :

Water samples with BOD values of 4 ppm and 18 ppm, respectively are :

A metal on combustion in excess air forms X. X upon hydrolysis with water yields \(\mathrm{H_2O_2}\) and \(\mathrm{O_2}\) along with another product. The metal is :

The volume of gas A is twice than that of gas B. The compressibility factor of gas A is thrice than that of gas B at same temperature. The pressures of the gases for equal number of moles are -

The correct order for acid strength of compounds :
\(\mathrm{CH\equiv CH}\), \(\mathrm{CH_3{-}C\equiv CH}\) and \(\mathrm{CH_2{=}CH_2}\) is as follows

The major product of the following reaction is

The standard electrode potential \(E^\circ\) and its temperature coefficient \(\left(\frac{dE^\circ}{dT}\right)\) for a cell are 2 V and \(-5\times10^{-4}\ \mathrm{VK^{-1}}\) at 300 K respectively. The cell reaction is
\(\mathrm{Zn(s) + Cu^{2+}(aq) \rightarrow Zn^{2+}(aq) + Cu(s)}\)
The standard reaction enthalpy \((\Delta_rH^\circ)\) at 300 K in \(\mathrm{kJ\ mol^{-1}}\) is, [Use \(R = 8\ \mathrm{JK^{-1}mol^{-1}}\) and \(F = 96{,}000\ \mathrm{C\ mol^{-1}}\)]

The major product of the following reaction is \(-\)

Among the following four aromatic compounds, which one will have the lowest melting point ?

The pair of metal ions that can give a spin only magnetic moment of 3.9 BM for the complex \(\mathrm{[M(H_2O)_6]Cl_2}\), is \(-\)

The element with Z = 120 (not yet discovered) will be an/a \(-\)

can not be prepared by \(-\)
(The structure shown is \(\mathrm{CH_3CH_2C(OH)(Ph)CH_3}\), i.e. 2-phenylbutan-2-ol.)

What is the work function of the metal if the light of wavelength \(4000\ \mathrm{\AA}\) generates photoelectrons of velocity \(6\times 10^{5}\ \mathrm{ms^{-1}}\) from it ?
(Mass of electron = \(9\times 10^{-31}\) kg;
Velocity of light = \(3\times 10^{8}\ \mathrm{ms^{-1}}\)
Plank's constant = \(6.626\times 10^{-34}\) Js;
Charge of electron = \(1.6\times 10^{-19}\ \mathrm{JeV^{-1}}\))

The increasing order of reactivity of the following compounds towards reaction with alkyl halides directly is

(The figure shows four structures labelled (A) benzamide, (B) phthalimide, (C) 2-aminobenzonitrile, (D) aniline.)

In the following reaction, products A and B are \(-\)

In the following reaction :
\(\text{Aldehyde} + \text{Alcohol} \xrightarrow{\ \mathrm{HCl}\ } \text{Acetal}\)

Aldehyde	Alcohol
HCHO	tBuOH
\(\mathrm{CH_3CHO}\)	MeOH

The best combination is

Decomposition of X exhibits a rate constant of \(0.05\ \mu\mathrm{g/year}\). How many year are required for the decomposition of \(5\ \mu\mathrm{g}\) of X into \(2.5\ \mu\mathrm{g}\)?

The higher concentration of which gas in air can cause stiffness of flower buds?

The hydride that is NOT electron deficient :