List of top Chemistry Questions

An organic compound contains carbon, hydrogen and oxygen. Its elemental analysis gave C, 38.71% and H, 9.67%. The empirical formula of the compound would be
Bond dissociation enthalpy of ${H_2, Cl_2}$ and $HCl$ are $434, 242$ and ${431 \, kJmol^{- 1}}$ respectively. Enthalpy of formation of $HCl $ is
Equal volumes of three acid solutions of pH 3, 4 and 5 are mixed in a vessel. What will be the $ H^+ $ ion concentration in the mixture?
For the gas phase reaction, ${PCl_{5} (g) <=> PCl_{3} (g) + Cl_{2} (g)}$ which of the following conditions are correct ?
How many moles of lead (II) chloride will be formed from a reaction between 6.5 g of PbO and 3.2 g of HCl?
How many stereoisomers does this molecule have? $CH_3CH = CHCH_2CHBrCH_3$
Standard free energies of formation (in kj/mol) at 298 K are -237.2, -394.4 and -8.2 for $H_2O(l),CO_2(g) $ and pentane (g), respectively. The value of $E^0_{cell} $ for the pentane-oxygen fuel cell is
The dissociation equilibrium of a gas $ AB_2 $ can be represented as $2 A B_2(g) \rightleftharpoons 2 A B (g) + B_2 (g) $ The degree of dissociation is $x$ and is small compared to $1$. The expression relating the degree of dissociation (x) with equilibrium constant $K_p$ and total pressure $p$ is
Volume occupied by one molecule of water $(density\, = 1 g\, cm^{-3} )$ is
What volume of oxygen gas $(O_2)$ measured at $0^\circ C$ and 1 atm, is needed to bum completely 1L of propane gas $(C_3H_8)$ measured under the same conditions?
Which of the following are not state functions? (I) q + W (II) q (III) w (IV) H-TS
A strong base can abstract an $\alpha$-hydrogen from
Green chemistry means such reactions which
The relative reactivities of acyl compounds towards nucleophilic substitution are in the order of
The correct order of decreasing second ionisation enthalpy of Ti(22), V(23), Cr(24) and Mn(25) is
Base strength of (i) $h_3C \, {C} ^{\ominus} H_2$ (ii) $H_2 C= {C}^{\ominus} H$ (iii) $H-C \equiv C^{\ominus} $ is in the order of
Equimolar solutions of the following were prepared in water separately. Which one of the solutions will record the highest pH ?
Number of moles of $MnO^{-}_4$ required to oxidise one mole of ferrous oxalate completely in acidic medium will be
On the basis of the following $E^0 $ values, the strongest oxidising agent is $[Fe(CN)_6]^{4-} \rightarrow [Fe(CN)_6]^{3-}+e^-; $ $\hspace15mm E^0=-0.35 V $ $Fe^{2+} \rightarrow Fe^{3+} + e^-;E^0=-0.77 V $
The angular shape of ozone molecule $ (O_3 )$ consists of
The number of formula units of calcium fluoride, $CaF _{2}$ present in $146.4\, g$ of $CaF _{2}$ (the molar mass of $CaF _{2}$ is $78.08 \,g / mol$ ) is
When $25\, g$ of a non-volatile solute is dissolved in $100\,g$ of water, the vapour pressure is lowered by $2.25 \times 10^{-1}\, mm$. If the vapour pressure of water at $20^{\circ} C$ is $17.5\, mm$, what is the molecular weight of the solute?
The standard reduction potentials at 298 K for half-cell reactions are given:
\( \mathrm{Zn}^{2+} + 2e^{-} \rightarrow \mathrm{Zn};\ -0.762\,\text{V} \)
\( \mathrm{Cr}^{3+} + 3e^{-} \rightarrow \mathrm{Cr};\ -0.74\,\text{V} \)
\( 2\mathrm{H}^{+} + 2e^{-} \rightarrow \mathrm{H}_{2};\ 0.00\,\text{V} \)
\( \mathrm{Fe}^{3+} + e^{-} \rightleftharpoons \mathrm{Fe}^{2+};\ +0.77\,\text{V} \)
The strongest reducing agent is:
The electronic configuration \( 1s^{2}\, 2s^{2}\, 2p^{6}\, 3s^{2}\, 3p^{6}\, 3d^{10} \) represents:
In which of the following complex ion, the central metal ion is in a state of \( sp^{3}d^{2} \) hybridisation?