A chemical that depletes the ozone layer is:
1. Sulphur
2. Chlorofluorocarbons (CFCs)
3. Nitrogen
4. Hydrogen
Oxygen forms hydrogen bonds while chlorine does not, because :
1. | Chlorine has a bigger size and as a result, a higher electron density per unit volume. |
2. | Oxygen has a smaller size and as a result, a lower electron density per unit volume. |
3. | Oxygen has a smaller size and as a result, a higher electron density per unit volume. |
4. | Oxygen has a bigger size and as a result, a higher electron density per unit volume. |
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.
1. | Neon gas is filled in discharge tubes with characteristic colours. |
2. | Neon gas is used in beacon lights. |
3. | Argon along with nitrogen is used in gas-filled electric lamps. |
4. | All of the above. |
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. |
Nitrogen exists as a diatomic molecule and phosphorus as P4 because on moving
1. | up a group, the tendency to form pπ−pπ bonds decreases. |
2. | down a group, the tendency to form pπ−pπ bonds decreases. |
3. | down a group, the tendency to form dπ−dπ bonds decreases. |
4. | up a group, the tendency to form dπ−dπ bonds decreases. |
NH3 forms a hydrogen bond but PH3 does not because:
1. | Phosphorus is more electronegative as compared to nitrogen. |
2. | Nitrogen is more electronegative as compared to phosphorus. |
3. | Nitrogen and phosphorous have equal electronegativity. |
4. | Nitrogen is more stable as compared to phosphorus. |
A compound having two direct bonds between P and H atoms is:
1.
2.
3.
4.
Assertion (A): | The valency and oxidation number of sulphur in S8 respectively are 2 and 0. |
Reason (R): | S8 Rhombic is the most stable allotropic form of sulphur. |
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. | Both (A) and (R) are false. |
Assertion (A): | Noble gases have the highest ionization energies in their respective periods. |
Reason (R): | The outermost sub-shell of noble gases in which the electron enters is completely filled. |
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. | Both (A) and (R) are false. |