Choose the incorrect statement among the following regarding noble gases:

1.	Noble gases have weak dispersion forces.
2.	Noble gases have large positive values of electron gain enthalpy.
3.	Noble gases are sparingly soluble in water.
4.	Noble gases have very high melting and boiling points.

In which one of the following arrangements the given sequence is not strictly according to the properties indicated against it?

NaCl when heated with sulphuric acid in the presence of ${\mathrm{MnO}}_2$, gives:

1. MnO

2. MnCl₂

3. Cl₂

4. Both (2) and (3)

The products formed by the reaction of F₂ and Cl₂ with water respectively are:

1. HF , HCl

2. H₂F₂ , HOCl

3. HF, HClO₃

4. H₂F₂, HClO₄

Oxygen exists as gas and sulphur exists as a solid because:
1. Oxygen is less electronegative than sulphur.

2. Sulphur is smaller than oxygen molecule.

3. Sulphur has a tendency to form pπ-pπ bonds.

4. Oxygen has a tendency to form pπ-pπ bonds.

The correct statement(s) among the given options is/are:

The main product(s) formed in the given reaction is/are:

${\mathrm{NH}}_4\mathrm{Cl}\left(\mathrm{aq}\right)+{\mathrm{NaNO}}_2\left(\mathrm{aq}\right)\to ....+{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)+\mathrm{NaCl}\left(\mathrm{aq}\right)$

$1. {\mathrm{NH}}_3$
$2. {\mathrm{N}}_2$
$3. {\mathrm{N}}_2{\mathrm{H}}_4$
$4. \mathrm{Both} \left(1\right)\hspace{0.17em}\mathrm{and}\left(3\right)$

The correct statement(s) regarding group 15 elements is(are):