${\mathrm{Al}}_2{\mathrm{O}}_3$ reacts with which of the following?

1.  Only water

2.  Only acids

3.  Only alkalies

4.  Both acids and alkalies

The element which exists in a liquid state for a wide range of temperatures and can be used for measuring high temperature is:

Which of the following is a Lewis acid?

1. ${\mathrm{AlCl}}_3$

2. ${\mathrm{MgCl}}_2$

3. ${\mathrm{CaCl}}_2$

4. ${\mathrm{BaCl}}_2$

The geometry of a complex species can be understood from the knowledge of the type of hybridization of orbitals of the central atom. The hybridization of orbitals of a central atom in ${\left[\mathrm{B}\right({\mathrm{OH}}_4\left)\right]}^{-}$ and the geometry of the complex are respectively

Boric acid is an acid because its molecule

1. Contains replaceable H⁺ ion

2. Gives up a proton

3. Accepts OH^- from water releasing proton

4. Combines with proton from water molecule

What is the correct increasing order of tendency for catenation among group 14 elements?

1.  $\mathrm{C}>\mathrm{Si}>\mathrm{Ge}>\mathrm{Sn}$

2.  $\mathrm{C}>>\mathrm{Si}>\mathrm{Ge}\approx \mathrm{Sn}$

3.  $\mathrm{Si}>\mathrm{C}>\mathrm{Sn}>\mathrm{Ge}$

4.  $\mathrm{Ge}>\mathrm{Sn}>\mathrm{Si}>\mathrm{C}$

Which of the following is true regarding the structure of diborane?

A compound X, of boron, reacts with NH₃ on heating to give another compound Y which is called inorganic benzene. The compound X can be prepared by treating BF₃ with lithium aluminum hydride. The compounds X and Y are represented by the formulas.

1.  B₂H₆, B₃N₃H₆

2.  B₂O₃, B₃N₃H₆

3.  BF₃, B₃N₃H₆

4.  B₃N₃H₆, B₂H₆

Quartz is extensively used as a piezoelectric material, it contains-

What is dry ice?