On addition of conc. to a chloride salt, colourless fumes are evolved but in case of iodide salt, violet fumes come out. This is because:
1. | reduces HI to | 2. | HI is of violet colour |
3. | HI gets oxidised to | 4. | HI changes to HI |
In qualitative analysis when is passed through an aqueous solution of salt acidified with dil. HCl, a black precipitate is obtained. On boiling the precipitate with dil. , it forms a solution of blue colour. Addition of excess of aqueous solution of ammonia to this solution gives:
1. Deep blue precipitate of Cu(OH)2
2. Deep blue precipitate of [Cu(NH3)4]2+
3. Deep blue precipitate of Cu(NO3)2
4. Deep blue solution of Cu(OH)2 . Cu(NO3)2
In a cyclotrimetaphosphoric acid molecule, how many single and double bonds are present?
1. | 3 double bonds; 9 single bonds. |
2. | 6 double bonds; 6 single bonds |
3. | 3 double bonds; 12 single bunds |
4. | Zero double bonds; 12 single bonds |
Which of the following elements can be involved in pπ-dπ bonding?
1. Carbon
2. Nitrogen
3. Phosphorus
4. Boron
Affinity for hydrogen decreases in the group from fluorine to iodine. Which of the halogen acids should have highest bond dissociation enthalpy?
1. | HF | 2. | HCl |
3. | HBr | 4. | HI |
The bond dissociation enthalpy of E—H (E = element) bonds is given below. Which of the compounds will act as the strongest reducing agent?
Compound |
||||
389 |
322 |
297 |
255 |
On heating with concentrated NaOH solution in an inert atmosphere of white phosphorus gives a gas. Which of the following statement is incorrect about the gas?
1. | It is highly poisonous and has smell like rotten fish |
2. | Its solution in the water, decomposes in the presence of light |
3. | It is more basic than NH3 |
4. | It is less basic than NH3 |
Strong reducing behavior of is due to
1. Low oxidation state of phosphorus
2, Presence of two — OH groups and one P— H bond
3. Presence of one — OH group and two P— H bonds
4. High electron gain enthalpy of phosphorus
Assertion (A): | SF6 cannot be hydrolysed but SF4 can be. |
Reason (R): | Six F-atoms in SF6 prevent the attack of H2O on sulphur atom of SF6 |
1. | Both (A) and (R) are True and (R) is the correct explanation of (A). |
2. | Both (A) and (R) are True but (R) is not the correct explanation of (A). |
3. | (A) is True but (R) is False. |
4. | (A) is False but (R) is True. |
Assertion (A): | NaCl reacts with concentrated H2SO4 to give colourless fumes with a pungent smell. But on adding MnO2, the fumes become greenish-yellow. |
Reason (R): | MnO2 oxidizes HCl to chlorine gas which is greenish-yellow. |
1. | Both (A) and (R) are True and (R) is the correct explanation of (A). |
2. | Both (A) and (R) are True but (R) is not the correct explanation of (A). |
3. | (A) is True but (R) is False. |
4. | (A) is False but (R) is True. |