List of top Chemistry Questions

A first order reaction is 50% complete in 30 minutes at 300 K and in 10 minutes at 320 K. The activation energy of the reaction ($E_a$) is: [R = 314 J K$^{-1}$ mol$^{-1}$, log 2 = 3010; log 3 = 4771]

The quantity of $\text{Ca}$ that can be produced from molten $\text{CaCl}_2$, with the same quantity of electricity (in coulombs) required to produce $8\text{ g}$ of $\text{Mg}$ from molten $\text{MgCl}_2$ is: [Atomic mass of $\text{Mg} = 24\text{ u}$; Atomic mass of $\text{Ca} = 40\text{ u}$]}

Identify the INCORRECT statement.

x moles of $\text{K}_2\text{Cr}_2\text{O}_7$ oxidises 1 mole of ferrous oxalate, in acidic medium. Hence 'x' is:

What is the major product [P3] formed when n-Hexane undergoes the given series of reactions?

n-Hexane $\xrightarrow[\text{20 atm, 773 K}]{\text{V}_2\text{O}_5}$ [P] $\xrightarrow[\Delta]{\text{C}_2\text{H}_5\text{Cl, Anhyd. AlCl}_3}$ [P2] $\xrightarrow[\text{333 K}]{\text{Conc. HNO}_3 + \text{H}_2\text{SO}_4}$ [P3]}

The $\Delta G^\circ$ for the reaction, $\text{Cd}^{2+}(aq) + \text{Zn}(s) \rightarrow \text{Zn}^{2+}(aq) + \text{Cd}(s)$ is: (Given $E_{\text{Cd}^{2+}/\text{Cd}}^\circ = -403\text{ V}$, $E_{\text{Zn}^{2+}/\text{Zn}}^\circ = -763\text{ V}$)}

What is the major product [Z] formed when compound [C] undergoes the following reactions?

[C] (Cyclohexyl bromide) $\xrightarrow[\Delta]{\text{alc. KOH}$ [X] $\xrightarrow{\text{HCl}}$ [Y] $\xrightarrow{\text{(i) alc. KCN, (ii) dil. HCl}}$ [Z]}

Choose the incorrect statement.

Among the given resonating structures of molecules negative mesomeric effect is represented by:

In the synthesis of $\text{NH}_3$ from $\text{H}_2$ and $\text{N}_2$ if $6\times10^{-2}$ mole of hydrogen disappears in 10 minutes, the number of moles of $\text{NH}_3$ formed in 3 minutes is:

When a metal of work function $4\text{ eV}$ is exposed to radiation, the maximum kinetic energy of the emitted electrons is $4\text{ eV}$. The stopping potential required is:

The basic principle behind the working of an electron microscope is:

A hydrogen atom absorbs energy and rises to the $n = 3$ state from its ground state $n = 1$. If the potential energy of the atom at its ground state is $-22\text{ eV}$, find the wavelength emitted by it when it returns to its ground state: (Take Planck's constant $= 6 \times 10^{-34}\text{ J s}$, speed of light $= 3 \times 10^8\text{ m s}^{-1}$)}

The variation of the stopping potential ($V_0$) with the frequency of incident radiation ($\nu$) is plotted. If $\nu_0$ is the threshold frequency, $h$ is Planck's constant, and $e$ is the electronic charge, then the slope of the graph with the frequency axis is:

Calculate the vapour pressure that can help the formation of a spherical droplet of water of radius $25 \times 10^{-5}\text{ m}$ at $22^\circ\text{C}$. Given: The surface tension of water at the given temperature is $28 \times 10^{-2}\text{ N m}^{-1}$.

One mole of benzene is mixed with one mole of toluene. The vapours above the solution contain:

Which of the following is true for a spontaneous galvanic cell?

Arrange in increasing order of boiling points: (A) 2,2-dimethylpropane, (B) 2-methylbutane, (C) n-pentane, (D) n-butane.

Assertion (A): Highest oxidation state of Mn is +7 in most of the transition elements.
Reason (R): Transition metals exhibit variable oxidation states.

Which of the following is most basic?

Calculate the boiling point of a solution containing 0.61 g of benzoic acid (122 \( g mol^{-1} \)) in 5 g of \( CS_2 \) in which it dimerises to 88%. \( T_b^\circ(CS_2) = 46.2^\circ C, K_b = 2.3 K kg mol^{-1} \).

Ethylene glycol ($\text{ethane-1,2-diol}$) is widely added to car radiators as an antifreeze agent. How does its addition protect the engine in extreme climates?

What are the primary reagents and catalysts required to carry out the Gattermann-Koch reaction?

What are the starting materials used in the industrial synthesis of the pesticide DDT?