The compound among the following with the lowest pK_a value is?

1. H₂O

2. H₂S

3. H₂Se

4. H₂Te

Nitrogen gas is liberated by the thermal decomposition of:

1. ${\mathrm{NH}}_4{\mathrm{NO}}_2$                                 

2. ${\mathrm{NaN}}_3$

3. ${\left({\mathrm{NH}}_4\right)}_2{\mathrm{Cr}}_2{\mathrm{O}}_7$                           

4. All of the above. 

The number of \(\mathrm{S=O}\) bonds present in \(\mathrm{H}_2\mathrm{S}_2 \mathrm{O}_8\) is:

Among the following molecules, 

(i) $\stackrel{..}{X}e{O}_3$

(ii) $\stackrel{..}{X}eO{F}_4$

(iii) $\stackrel{..}{X}e{F}_6$

Those having the same number of lone pairs on Xe are

1. (i) and (ii) only

2. (i) and (iii) only

3. (ii) and (iii) only

4. (i), (ii) and (iii) only

Incorrect order among the following is:

The respective oxidation states of P in H₄P₂O₅, H₄P₂O₆, and H₄P₂O₇ are: 

What order does the stability of interhalogen compounds follow?

1. IF₃  > BrF₃  > CIF₃

2. BrF₃ > IF₃ > ClF₃

3. ClF₃ > BrF₃ > IF₃

4. ClF₃ > IF₃ > BrF₃

The molecular shapes of SF₄, CF₄ and XeF₄ are: 

Which of the following liquids has the ability to climb the glass vessel's wall?

1. Alcohol 

2. Liquid He

3. Liquid $N_2$

4. Water

The gas that is used in the gas thermometer is: