Which of the following is the correct sequence of increasing first ionisation energy?

1. $Pb<Sn<C<Si$

2. $Pb<C<Si<Sn$

3. $Sn<Pb<Si<C$

4. $Sn<C<Si<Pb$

The product formed by the reaction of  diborane and ammonia in the presence of heat is:

1.  ${\mathrm{BH}}_3$

2.  ${\mathrm{NH}}_4{\mathrm{BH}}_4$

3.  ${\mathrm{NH}}_2{\mathrm{NH}}_2$

4.  ${\mathrm{B}}_3{\mathrm{N}}_3{\mathrm{H}}_6$

Which of the following compound(s) can react with ${\mathrm{BF}}_3$?

1.  Ethers

2.  ${\mathrm{H}}_2\mathrm{O}$

3.  ${\mathrm{NH}}_3$

4.  All of the above

Which of the following types of metals respond to the borax bead test?

1. Divalent metals

2. Heavy metals

3. Light metals

4. Metals that forms coloured metaborates

Which of the following explains why aluminium becomes passive in nitric acid?

1. It is a noble metal

2. It forms a thin film of oxide

3. It has positive reduction potential

4. None of the above

Mark the oxide which is amphoteric in character:

1. CO₂

2. CO

3. SnO₂

4. CaO

${\mathrm{Al}}_2{\mathrm{O}}_3$ 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