List of top Chemistry Questions

Molecular orbital theory was given by:

$CH_3Br+ Nu^- \to CH_3 - Nu + Br^-$ The decreasing order of the rate of the above reaction with nucleophiles $(Nu^-)$A to D is : $ [Nu^- = (A)PhO^-, (B)AcO^-, (C)HO^-,(D)CH_3O^-]$

Among the following which one can have a meso form?

The empirical formula of a compound is $CH _{2}$. One mole of this compound has a mass of $42\, g$. Its molecular formula is :

Which of the following statements is incorrect?

$ Ag^+ \, + NH_3 \rightleftharpoons [ Ag ( NH_3 ) ]^+ ; K_1 = 3.5 \times 10^{ - 3 } $ $ [ Ag ( NH_3 )]^+ \, + NH_3 \rightleftharpoons [ Ag (NH_3 )_2 ]^+ ; K_2 = 1.7 \times 10^{ - 3 } $ then the formation constant of $ [ Ag (NH_3)_2]^+ $ is...

Some chemists at ISRO wished to prepare a saturated solution of a silver compound and they wanted it to have the highest concentration of silver ion possible. Which of the following compounds, would they use? $K_{s p}( AgCl )=1.8 \times 10^{-10} $ $K_{s p}( AgBr )=5.0 \times 10^{-13} $ $K_{s p}\left( Ag _{2} CrO _{4}\right)=2.4 \times 10^{-12}$

$40\, ml$ of $0.1\, M$ ammonia solution is mixed with $20 \,ml$ of $0.1\, M\, HCl$. What is the $pH$ of the mixture? $\left( p K_{b}\right.$ of ammonia solution is $\left.4.74\right)$

Transition elements are generally used as catalyst because

The enzyme responsible for atmospheric nitrogen fixation is:

The standard enthalpy of formation $\left(\Delta H^{\circ}_{f}\right)$ at 298 K for methane, $CH_4(g)$, is $- 74.8 \,kJ\, mol^{-1}$. The additional information required to determine the average energy for C�H bond formation would be:

The reagent used in Gatterman Koch aldehyde synthesis is:

The formula mass of Mohr's salt is $392$. The iron present in it is oxidised by $KMnO_4$ in acid medium. The equivalent mass of Mohr's salt is

The enthalpy of combustion at $25^{\circ} C$ of $H _{2}$, cyclohexane $\left( C _{6} H _{12}\right)$ and cyclohexene $\left( C _{6} H _{10}\right)$ are $-241,-3920$ and $-3800\, kJ / mol$ respectively. The heat of hydrogenation of cyclohexene is :

The element ${ }_{90} Th ^{232}$ belongs to thorium series. Which of the following will act as the end product of the series?

$ PCl_{3} $ and cold water reacts to produce which of the following?

Nitrobenzene on treatment with zinc dust and aqueous ammonium chloride gives

Methyl- $\alpha-D$-glucoside and methyl $-\beta-D$-glucoside are

Which of the following electronic configuration represents noble gas?

When calcium acetate is distilled, it will produce which of the following compound?

Which among the following species have the same number of electrons in its outermost as well as penultimate shell?

The ability of a given substance to assume two or more crystalline structure is called :

$C_{6} H_{5}-C H=C H C H O \xrightarrow{X} C_{6} H_{5} C H=C H C H_{2} O H$ In the above sequence $X$ can be:

For a reaction $H _{2}+ I _{2} \rightleftharpoons 2 HI$ at $721\, K$, the value of equilibrium constant is $50$. If $0.5$ moles each of $H_{2}$ and $I_{2}$ is added to the system, the value of equilibrium constant will be:

Which of the following is dihydric alcohol?