List of top Chemistry Questions

Equimolar concentrations of $H_2$ and $I_2$ are heated to equilibrium in a 2 litres flask. At equilibrium, the forward and the backward rate constants are found to be equal. What percentage of initial concentration of $H_2$ has reacted at equilibrium ?

For a polybasic acid, the dissociation constants have a different values for each step, e.g., $ {H3A <=> H+ +H2A^-}$ ; $K=K_{a_1}$ $ {H2A- <=> H+ +H2A^{2-}}$ ; $K=K_{a_2}$ $ {HA^{2-} <=> H+ +A^{3-}}$ ; $K=K_{a_3}$ What is the observed trend of dissociation constants in successive stages?

For preparing a buffer solution of pH 6 by mixing sodium acetate and acetic acid, the ratio of the concentration of salt and acid should be $(K_a= 10^{-5})$

For the gas phase reaction $ {2NO<=>N2 +O2}$ $?H = - 43.5 \,kcal\, mol^{-1}$ which one of the statements below is true for $ {N_{2(g)} +O_{2(g)} <=> 2NO_{(g)}}$

For the reaction $ {2NO_{2(g)} <=> N2O_{4(g)}, K_{p}/K_{c}}$ is equal to

For the reaction : $ {H2_{(g)} +I2_{(g)} <=> 2HI_{(g)}}$, the standard free energy is $\Delta G^{\circ} > 0$. The equilibrium constant $(K)$ would be________.

Formation of $ClF_3$ from $Cl_2$ and $F_2$ is an exothermic process. The equilibrium system can be represented as $ {Cl2_{(g)} +3F2_{(g)}<=>2ClF3}$ ; $\Delta H=-329\,kj\,mol^{-1}$ Which of the following will increase quantity of $ClF_3$ in the equilibrium mixture?

How many gram equivalents of NaOH are required to neutralize 25 $cm^3$ of decinormal HCl solution ?

If $K_{sp}$ of $Mg(OH)_2$ is $1.2 ? 10^{-11}$. Then the highest pH of the $0.1\, M$ solution of $Mg^{2+}$ ion from which $Mg(OH)_2$ is not precipitated is

If pH of a solution decreases from 5 to 2, then it is

If $S_1, S_2, S_3$ and $S_4$ are the solubilities of $AgCl$ in water, in $0.01\, M\, CaCl_2$, in $0.01\, M\, NaCl$ and in $0.05\, M\, AgNO_3$ respectively at a certain temperature, the correct order of solubilities is

If the solubility of $Ag_2CrO_4$ is S mole/litre.Then its solubility product is

In a vessel $N_2$, $H_2$ and $NH_3$ are at equilibrium. Some helium gas is introduced into the vessel so that total pressure increases while temperature and volume remain constant. According to Le Chatelier's principle, the dissociation of $NH_3$

In an experiment, $NO_2$ gas is prepared and taken into $3$ test tubes $X$, $Y$ and $Z$. $NO_2$ gas which is brown in colour dimerises into $N_2O_4$ which is colourless. Test tube $X$ is kept at room temperature, $Y$ is kept in ice and $Z$ is kept in hot water. What colour changes will you observe in the test tubes and why? $\underset{\text{Brown}}{ {2NO2_{(g)} <=> }}$ $\underset{\text{Colourless}}{ {N2O4_{(g)}}}$ ; $\Delta H=-57.2\,kJ\,mol^{-1}$

In the lime kiln, the reversible reaction $ {CaCO3 <=> CaO +CO2}$ proceeds to completion because of

In the relation, $K_p = K_c (RT)^{\Delta n}$ the value of $\Delta n$ is

$K_a$ for $CH_3COOH$ is $1.8 \times 10^{-5}$ and $K_b$ for $NH_4OH$ is $1.8 \times 10^{-5}$. The $pH$ of ammonium acetate will be

$NH_4CN$ is a salt of weak acid $HCN (K_a = 6.2 \times 10^{-10})$ and a weak base $NH_4OH (K_b = 1.8 \times 10^{-5})$. A one molar solution of $NH_4CN$ will be

pH of $0.01 M (NH_4)_2 SO_4$ and $0.02 \,M\, NH_4OH $ buffer $(pK_a of NH^+_4 = 9.26)$ is

The expression for the solubility product of $Ag_2CO_3$ will be :

The theory of spontaneous generation stated that

The vapour density of $N_2O_4$ at a certain temperature is 30. What is the percentage dissociation of $N_2O_4$ at this temperature ?

Three sparingly soluble salts $M_2X, MX$ and $MX_3$ have same value of solubility product. Their solubilities follow the order

Vapour density of $PCl_5$ is $104.16$ but when heated to $230^{\circ} C$ its vapour density is reduced to 62. The degree of dissociation of $PCl_5$ at this temperature will be

Water is a