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JEE Mains | PYQ

From the given list, the number of compounds with +4 oxidation state of Sulphur is ___________ .
$\text{SO}_3$, $\text{H}_2\text{SO}_3$, $\text{SOCl}_2$, $\text{SF}_4$, $\text{BaSO}_4$, $\text{H}_2\text{S}_2\text{O}_7$

The lowest oxidation number of an atom in a compound \( \mathrm{A_2B} \) is \( -2 \). The number of electrons in its valence shell is _______.

Which of the following reactions are disproportionation reactions?
(A) \( \text{Cu}^+ \rightarrow \text{Cu}^{2+} + \text{Cu} \)
(B) \( 3\text{MnO}_4^{2-} + 4\text{H}^+ \rightarrow 2\text{MnO}_4^- + \text{MnO}_2 + 2\text{H}_2\text{O} \)
(C) \( 2\text{KMnO}_4 \rightarrow \text{K}_2\text{MnO}_4 + \text{MnO}_2 + \text{O}_2 \)
(D) \( 2\text{MnO}_4^- + 3\text{Mn}^{2+} + 2\text{H}_2\text{O} \rightarrow 5\text{MnO}_2 + 4\text{H}^+ \)
Choose the correct answer from the options given below:

Only \( 2 \, \mathrm{mL} \) of \( \mathrm{KMnO}_4 \) solution of unknown molarity is required to reach the end point of a titration of \( 20 \, \mathrm{mL} \) of oxalic acid \( (2 \, \mathrm{M}) \) in acidic medium. The molarity of \( \mathrm{KMnO}_4 \) solution should be \( \_\_\_\_\_\_ \, \mathrm{M} \).

Chlorine undergoes disproportionation in alkaline medium as shown below:
\( a\mathrm{Cl_2}(g) + b\mathrm{OH^-}(aq) \rightarrow c\mathrm{ClO^-}(aq) + d\mathrm{Cl^-}(aq) + e\mathrm{H_2O}(l) \)
The values of \( a \), \( b \), \( c \) and \( d \) in a balanced redox reaction are respectively:

Thiosulphate reacts differently with iodine and bromine in the reactions given below:
\( 2\mathrm{S_2O_3}^{2-} + \mathrm{I_2} \rightarrow \mathrm{S_4O_6}^{2-} + 2\mathrm{I^-} \)
\( \mathrm{S_2O_3}^{2-} + 5\mathrm{Br_2} + 5\mathrm{H_2O} \rightarrow 2\mathrm{SO_4}^{2-} + 4\mathrm{Br^-} + 10\mathrm{H^+} \)
Which of the following statement justifies the above dual behaviour of thiosulphate?