$15 \ mL$ of aqueous solution of $Fe^{2+}$ in acidic medium completely reacted with $20 \ mL$ of $0.03 \ M$ aqueous $Cr_{2}O_{7}^{2-}$. The molarity of the $Fe^{2+}$ solution is ........... $\times 10^{-2} \ M$ (Round off to the Nearest Integer).

Which of the following reactions represents a redox reaction involving water?

In which of the following reactions, chlorine acts as an oxidising agent?
$(i)$ $CH_3CH_2OH + Cl_2 \longrightarrow CH_3CHO + HCl$
(ii) $CH_3CHO + Cl_2 \longrightarrow CCl_3CHO + HCl$
(iii) $CH_4 + Cl_2 \stackrel{hv}{\longrightarrow} CH_3Cl + HCl$
The correct answer is

$10 \, \text{mole}$ of ferric oxalate is oxidised by $x \, \text{mole}$ of $MnO_4^-$ in acidic medium. The value of $x$ is

$200 \ mL$ of $x \times 10^{-3} \ M$ potassium dichromate $(K_2Cr_2O_7)$ is required to oxidise $750 \ mL$ of $0.6 \ M$ Mohr's salt $(FeSO_4 \cdot (NH_4)_2SO_4 \cdot 6H_2O)$ solution in acidic medium. Here $x =$ ?

$50 \ mL$ of $0.1 \ M$ solution of a salt reacted with $25 \ mL$ of $0.1 \ M$ solution of sodium sulphite. The half-reaction for the oxidation of sulphite ion is:
$SO_{3}^{2-} (aq) + H_{2}O (l) \to SO_{4}^{2-} (aq) + 2H^{+} (aq) + 2e^{-}$
If the oxidation number of the metal in the salt was $+3$,what would be the new oxidation number of the metal?