Which of the following facts regarding boron and silicon is not true?

Which of the following facts regarding boron and silicon is not true?
  1. Boron and silicon are semiconductors
  2. Boron and silicon form halides which are not hydrolysed
  3. Boron and silicon react with magnesium to form magnesium boride and magnesium silicide which are decomposed by acids to give volatile borane and silane, respectively
  4. Both boron and silicon react with alkalis to form borates and silicates containing $\mathrm{BO}_{4}$ and $\mathrm{SiO}_{4}$ tetrahedral units, respectively

Solution

The halides of $\mathrm{B}$ and $\mathrm{Al}$ are hydrolysed.
$
\mathrm{BCl}_{3}+3 \mathrm{H}_{2} \mathrm{O} ightarrow \underset{\text { Boric acid }}{\mathrm{B}(\mathrm{OH})_{3}}+3 \mathrm{HCl} \text { and } \mathrm{SiCl}_{4}+4 \mathrm{H}_{2} \mathrm{O} \underset{\text { Silicic acid }}{ightarrow \mathrm{Si}(\mathrm{OH})_{4}+4 \mathrm{HCl}}
$

Asked in: JEE-TOPICTESTS-CHEMISTRY

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