2
MCQ (Single Correct Answer)
In qualitative analysis when $\mathrm{H}_2 \mathrm{~S}$ is passed through an aqueous solution of salt acidified with dil. HCl , a black precipitate is obtained. On boiling the precipitate with dil. $\mathrm{HNO}_3$, it forms a solution of blue colour. Addition of excess of aqueous solution of ammonia to this solution gives ............. .
A
deep blue precipitate of $\mathrm{Cu}(\mathrm{OH})_2$
B
deep blue solution of $\left[\mathrm{Cu}\left(\mathrm{NH}_3\right)_4\right]^{2+}$
C
deep blue solution of $\mathrm{Cu}\left(\mathrm{NO}_3\right)_2$
D
deep blue solution of $\mathrm{Cu}(\mathrm{OH})_2 \cdot \mathrm{Cu}\left(\mathrm{NO}_3\right)_2$
3
MCQ (Single Correct Answer)
In a cyclotrimetaphosphoric acid molecule, how many single and double bonds are present?
A
3 double bonds; 9 single bonds
B
6 double bonds; 6 single bonds
C
3 double bonds; 12 single bonds
D
Zero double bond; 12 single bonds
4
MCQ (Single Correct Answer)
Which of the following elements can be involved in $p \pi-d \pi$ bonding?
A
Carbon
B
Nitrogen
C
Phosphorus
D
Boron
5
MCQ (Single Correct Answer)
Which of the following pairs of ions are isoelectronic and isostructural?
A
$\mathrm{CO}_3^{2-}, \mathrm{NO}_3^{-}$
B
$\mathrm{CIO}_3^{-}, \mathrm{CO}_3^{2-}$
C
$\mathrm{SO}_3^{2-}, \mathrm{NO}_3^{-}$
D
$\mathrm{ClO}_3^{-}, \mathrm{SO}_3^{2-}$
6
MCQ (Single Correct Answer)
Affinity for hydrogen decreases in the group from fluorine to iodine. Which of the halogen acids should have highest bond dissociation enthalpy?
A
HF
B
HCl
C
HBr
D
HI