Which one of the following statements is not correct?

• Moissan boron is amorphous

• The reaction between boron and concentrated HNO₃, gives N₂O.

• Amorphous boron on heating with oxygen forms B₂O₃.

• Boron is a non-conductor of electricity.

Which one of the following is a correct set?

• Diamond, sp²

• Graphite, sp³

• Diamond, sp

• Graphite, sp²

Diborane reacts with HCl in the presence of AlCl₃ and liberates

• H₂

• Cl₂

• BCl₃

• Cl₂ and BCl₃

How many corners of SiO₄ units are shared in the formation of three dimensional silicates?

• 3

• 2

• 4

• 1

What is Z in the following reactions ?

$$\begin{gathered} {\mathrm{BCl}}_3+ {\mathrm{H}}_2 \underset{450°\mathrm{C}}{\overset{\mathrm{Cu}-\mathrm{Al}}{\to }} \mathrm{X} + \mathrm{HCl} \\ \mathrm{X} \stackrel{\mathrm{methylation}}{\to } \mathrm{Z} \end{gathered}$$

• (CH₃)BH₂

• (CH₃)₄B₂H₂

• (CH₃)₃B₂H₃

• (CH₃)₆B₂

Which one of the following elements on doping with germanium, make it a p-type semiconductor?

• Boron

• Selenium

• Arsenic

• Germanium

Which one of the following elements reacts with steam?

• C

• Ge

• Si

• Sn

228.

Pure silicon doped with phosphorus is

• amorphous

• p-type semiconductor

• n-type semiconductor

• insulator

Which one of the following correctly represents the variation of electronegatrvity (EN) with atomic number (Z) of group 13 elements?

Al³⁺, Fe³⁺, Zn²⁺ and Ni²⁺ ions are present in an acidic solution. Excess of ammonium chloride solution followed by addition of ammonium hydroxide solution. The available precipitate will contain

• Zn(OH)₂ and Ni(OH)₂

• Al(OH)₂ and Fe(OH)₃

• Zn(OH)₂ and Al(OH)₃

• Ni(OH)₂ and Fe(OH)₃