List of top Chemistry Questions

Stomach acid, a dilute solution of $HCl$ in water, can be neutralized by reaction with sodium hydrogen carbonate, $ {NaHCO_3_{(aq)} +HCL_{(aq)} ->NaCL_{(aq)} +H_2O_{(l)} +CO_2_{(g)} }$ How many milliliters of 0.125 M NaHCO solution are needed to neutralize 18.0 mL of 0.100 M HCL?

The pH of M/100 NaOH solution is :

The effect of a catalyst in a chemical reaction is to change

The minimum energy required for molecules to enter into a chemical reaction is called

Plots showing the variation of the rate constant $(k)$ with temperature $(T)$ are given below. The plot that follows Arrhenius equation is

Consider the decomposition of $N _{2} O _{5}$ as $N _{2} O _{5} \longrightarrow 2 NO _{2}+\frac{1}{2} O _{2}$ The rate of reaction is given by $\frac{-d\left[ N _{2} O _{5}\right]}{d t}=\frac{1}{2} \frac{d\left[ NO _{2}\right]}{d t}=2 \frac{d\left[ O _{2}\right]}{d t}=k_{1}\left[ N _{2} O _{5}\right]$ Therefore, $\frac{-d\left[ N _{2} O _{5}\right]}{d t}=k_{1}\left[ N _{2} O _{5}\right]$ $\frac{+d\left[ NO _{2}\right]}{d t} =2 k_{1}\left[ N _{2} O _{5}\right]$ $=k_{1}'\left[ N _{2} O _{5}\right] \frac{+d\left[ O _{2}\right]}{d t} =\frac{1}{2} k_{1}\left[ N _{2} O _{5}\right]=k_{1}'' \left[N _{2} O _{5}\right]$ Choose the correct option.

For a reversible chemical reaction where the forward process is exothermic, which of the following statements is correct ?

The unit of rate constant depends upon

The time for half life period of a certain reaction $A \to $ products is $1$ hour. When the initial concentration of the reactant $?A?$, is $2.0\, mol\, L^{-1}$, how much time does it take for its concentration to come from $0.50$ to $0.25\, mol\, L^{-1}$ if it is a zero order reaction ?

The overall order of the reaction is the sum of the exponents of all the reactants in the rate expression. There are many higher order reactions.

Consider the reaction : $Cl_{2(aq)} + H_2S_{(aq)} \to S_{(s)} + 2H^+_{(aq)} + 2Cl^-_{(aq)}$ The rate equation for this reaction is rate $= k [Cl_2] [H_2S]$ Which of these mechanisms is/are consistent with this rate equation ? $\left(A\right) Cl_{2} + H_{2}S \to H^{+} + Cl^{-} + Cl^{+} + HS^{-} $ (slow) $Cl^{+} + HS^{-} \to H^{+} + Cl^{-} + S $ (fast) $\left(B\right) H_{2}S \rightleftharpoons H^{+} + HS^{-}$ (fast equilibrium) $Cl_{2} + HS^{-} \to 2Cl^{-} + H^{+} + S$ (slow)

What will be the half-life period of a first order reaction with rate constant $k=5.5 \times 10^{-14} s^{-1}$ ?

In the first order reaction the relation between the velocity constant $(k_1)$ and half-life period $(t_{1/2})$ is

The rate of a chemical reaction

During the conversion of $NH _{2} OH \rightarrow N _{2} O$, the equivalent weight of $NH _{2} OH$ (mol. wt. of $NH _{2} OH$ is $M$ ) is

Which of the following has smallest number of molecules ?

The molarity of a $NaOH$ solution by dissolving $4 \,g$ of it in $250\, ml$ water is

In the reaction of sodium thiosulphate with $I_2$ in aqueous medium, the equivalent weight of sodium thiosulphate is equal to

In a titration, 25 $cm^3$ of 0.1 N oxalic acid solution requires 20 $cm^3$ of sodium hydroxide for complete neutralization. The mass of sodium hydroxide in 250 $cm^3$ solution is

Dulong and Petit's law (At. mass $\times$ Specific heat = 6.4) is valid only for

S.I. unit of atomic mass and molecular mass is kilograms. Atomic mass is equal to the mass of $6.023 \times 10^{24}$ atoms.

Number of atoms present in $4.25 \,g$ of $NH_3 $ is

If $1 \,mL$ of water contains $20$ drops then number of molecules in a drop of water is

In an experiment, $4 \,g$ of $ M_{2}O_{x} $ oxide was reduced to $2.8 \,g$ of the metal. If the atomic mass of the metal is $ 56\,g\,mol^{-1}, $ the number of $O$ atoms in the oxide is

The total number of atoms of all elements present in $ 1 $ mole of ammonium dichromate is