Question

Pick out the incorrect statement regarding halogens.

• A. Chlorine is hydrolysed by water to form hydrochloric acid and hypochlorous acid
• B. Bromine and iodine react with NaOH solution to form halide and halate ion
• C. Chlorine reacts with cold dilute NaOH solution to give sodium chloride and sodium chlorate
• D. Iodine forms a deep blue colour with starch solution

Answer 1

Answer: (C)

$Cl_{2}$ reacts with cold and dilute NaOH solution to form NaCl and NaOCl(sodium hypochlorite).
$2NaOH+Cl_{2} \rightarrow NaCl+NaClO+H_{2}O$
$Cl_{2}$ forms $NaCl$ and $NaClO_{3}$ (sodium chlorate) with hot and Concentrated $NaOH$
$6NaOH+3Cl_{2} \rightarrow 5NaCl+NaClO_{3}+3H_{2}O$
A. $Cl_{2}\left(a q\right)+H_{2}O\rightleftharpoons HCl+HOCl$
B. $6NaOH+3X_{2} \rightarrow 5NaX+NaXO_{3}+3H_{2};\left(\right.X=BrandI\left.\right)$
D. Starch reacts with Iodine in the presence of Iodide ion to form an intensely colored blue complex, which is visible at very low concentrations of Iodine, making it a very good indicator in both direct and indirect lodometric titrations