JEE Main 2020 — Chemistry Physical Chemistry
Consider the following reactions:
NaCl+K2Cr2O7+H2SO4(Conc.)→(A)+\text{NaCl}+{\text{K}}_{2}{\text{Cr}}_{2}{\text{O}}_{7}+\underset{(\text{Conc.})}{{\text{H}}_{2}{\text{SO}}_{4}}\rightarrow (\text{A})+NaCl+K2Cr2O7+(Conc.)H2SO4→(A)+ side products
(A)+NaOH→(B)+(A)+NaOH\rightarrow (B)+(A)+NaOH→(B)+ side products
(B)+H2SO4(dilute)+H2O2→(C)+(B)+\underset{(\text{dilute})}{{H}_{2}S{O}_{4}}+{H}_{2}{O}_{2}\rightarrow (C)+(B)+(dilute)H2SO4+H2O2→(C)+ side products
The sum of the total number of atoms in one molecule each of (A),(B)(A),(B)(A),(B) and (C)(C)(C) is ________
Held on 7 Jan 2020 · Verified 6 Jul 2026.
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(A)=CrO2Cl2(A)=Cr{O}_{2}C{l}_{2}(A)=CrO2Cl2
(B)=Na2CrO4(B)=N{a}_{2}Cr{O}_{4}(B)=Na2CrO4
(C)=CrO5(C)=Cr{O}_{5}(C)=CrO5
Chromyl chloride (CrO2Cl2)({\mathrm{CrO}}_{2}{\mathrm{Cl}}_{2})(CrO2Cl2) can be prepared by the reaction of potassium chromate or potassium dichromate with hydrogen chloride in the presence of sulfuric acid, followed by distillation. The sulfuric acid serves as the dehydration agent.
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80 mL of a hydrocarbon on mixing with 264 mL of oxygen in a closed U-tube undergoes complete combustion. The residual gases after cooling to 273 K occupy 224 mL. When the system is treated with KOH solution, the volume decreases to 64 mL. The formula of the hydrocarbon is :
What is the energy (in J atom$^{-1}$) required for the following process? $Li^{2+}(g) \rightarrow Li^{3+}(g) + e^-$ (Take the ionization energy for the H atom in the ground state as $2.18 \times 10^{-18}$ J atom$^{-1}$)
Consider the following reduction processes : $\mathrm{Al}^{3+}+3 \mathrm{e}^{-} \longrightarrow \mathrm{Al}(\mathrm{s}), \mathrm{E}^{0}=-1.66 \mathrm{~V}$ $\mathrm{Fe}^{3+}+\mathrm{e}^{-} \longrightarrow \mathrm{Fe}^{2+}, \mathrm{E}^{0}=+0.77 \mathrm{~V}$ $\mathrm{Co}^{3+}+\mathrm{e}^{-} \longrightarrow \mathrm{Co}^{2+}, \mathrm{E}^{0}=+1.81 \mathrm{~V}$ $\mathrm{Cr}^{3+}+3 \mathrm{e}^{-} \longrightarrow \mathrm{Cr}(\mathrm{s}), \mathrm{E}^{\circ}=-0.74 \mathrm{~V}$ The tendency to act as reducing agent decreases in the order :
X and Y are the number of electrons involved, respectively during the oxidation of $\mathrm{I}^{-}$to $\mathrm{I}_{2}$ and $\mathrm{S}^{2-}$ to S by acidified $\mathrm{K}_{2} \mathrm{Cr}_{2} \mathrm{O}_{7}$. The value of $\mathrm{X}+\mathrm{Y}$ is $\_\_\_\_$.
Identify the correct statements from the following: A. Heisenberg uncertainty principle is applicable to electrons. B. The size of $2p_x$ orbital is less than the size of $3p_x$ orbital. C. The energy of $2s$ orbital of H atom is equal to the energy of $2s$ orbital of Li. D. The electronic configuration of Cr is $[\text{Ar}] 3d^5 4s^1$ Choose the correct answer from the options given below:
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