List of top Chemistry Questions

$C_{6}H_{5}F^{18}$ is a $F^{18}$ radio-isotope labelled organic compound. $F^{18}$ decays by positron emission. the product resulting on decay is

The radius of the second Bohr orbit for hydrogen atom is: (Planck's Const. $h =6 . 6262 \times 10^{-34}\, Js$; mass of electron $=9 . 1091 \times 10^{-31}\, Kg$ charge of electron $e =1 .60210 \times 10^{-19} C$; permittivity of vacuum $\left.\left(\epsilon_{0}\right)=8 \cdot 854185 \times 10^{-12}\, Kg ^{-1}\, m ^{-3} A ^{2}\right)$

Which of the following reactions is an example of a redox reaction?

The correct statement regarding electrophile is :

A compound $M_{p} X_{q}$ has cubic close packing (ccp) arrangement of X. Its unit cell structure is shown below. The empirical formula of the compound is

The element $Z = 114$ has been discovered recently. It will belong to which of the following family/group and electronic configuration ?

What is the $SI$ unit of conductivity ?

Correct formula of the complex formed in the brown ring test for nitrates is

Mechanism of a hypothetical reaction $X _{2}+ Y _{2} \rightarrow 2 XY$ is given below: (i) $X_{2} \rightarrow X+X$ (fast) (ii) $X + Y _{2} \rightleftharpoons XY + Y$ ( slow ) (iii) $X + Y \rightarrow XY$ (fast) The overall order of the reaction will be

$tert-butyl\, methyl$ ether on treatment with hydrogen iodide in cold gives

On treatment of $100\, mL$ of $0.1\, M$ solution of $CoCl _{3} \cdot 6 H _{2} O$ with excess $AgNO _{3} ; 1.2 \times 10^{22}$ ions are precipitated. The complex is

When the heat of reaction at constant pressure is \(-5 \times 10^3\) cal and the entropy change is \(7.4 \, \text{cal} \, \text{deg}^{-1}\) at \(25^\circ\text{C}\), the reaction is predicted as

Predict the correct intermediate and product in the following reaction :
$H_{3}C-C\equiv CH\underset{HgS{O}_4}{\overset{H_{2}O,H_{2}S{O}_4}{\to }}\underset{\text{(A)}}{\mathrm{Intermediate}}\to \underset{\text{(B)}}{\mathrm{product}}$

The e.m.f. of a Daniell cell at $298\, K$ is $E _{1}$. $Zn / SO _{4}(0.01 M ) \| CuSO _{4}(1.0 M ) / Cu$ When the concentration of $ZnSO _{4}$ is $1.0\, M$ and that of $CuSO _{4}$ is $0.01\, M$, the e.m.f. is changed to $E _{2}$. What is the relationship between $E _{1}$ and $E _{2}$ :

A metal crystallises in a face centred cubic structure. If the edge length of its unit cell is $'a'$, the closest approach between two atoms in metallic crystal will be :

The rate of a reaction quadruples when the temperature changes from $300$ to $310\, K$. The activation energy of this reaction is : (Assume activation energy and pre-exponential factor are independent of temperature; $ln\, 2 = 0.693; R=8.314 \,J$ $mol^{-1} \, K^{-1}$)

The Tyndall effect is observed only when following conditions are satisfied (a) The diameter of the dispersed particles is much smaller than the wavelength of the light used. (b) The diameter of the dispersed particle is not much smaller than the wavelength of the light used (c) The refractive indices of the dispersed phase and dispersion medium are almost similar in magnitude (d) The refractive indices of the dispersed phase and dispersion medium differ greatly in magnitude

The number of $S=O$ and $S-OH$ bonds present in peroxodisulphuric acid and pyrosulphuric acid respectively are :

Consider the following reaction,

X is

The volume of water to be added to 100 cm³ of 0.5 N H₂SO₄ to get decinormal concentration i

In which of the following the oxidation number of oxygen has been arranged in increasing order ?

Aqueous 10% NaHCO₃ solution is used as a reagent for identifying 'A'. Which of the following compounds yield 'A' on hydrolysis ?

Sulphur reacts with chlorine in 1 : 2 ratio and forms X. Hydrolysis of X gives a sulphur compound Y. The hybridization of central atom in the anion Y is

Which of the following region is coldest ?

Flux is used to