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

1.	NH3 < PH3 < AsH3 < SbH3	Increasing acidic character
2.	CO2 < SiO2 < SnO2 < PbO2	Increasing oxidizing power
3.	HF < HCl < HBr < HI	Increasing acidic strength
4.	H2O < H2S < H2Se < H2Te	Increasing pKa values

Choose the incorrect statement among the following regarding noble gases:

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):