Assertion (A): | First ionization energy for nitrogen is lower than that of oxygen. |
Reason (R): | Across a period, effective nuclear charge decreases. |
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. |
1. Cr > Mn > V > Ti
2. V > Mn > Cr > Ti
3. Mn > Cr > Ti > V
4. Ti > V > Cr > Mn
For the second-period elements, the correct increasing order of first ionisation enthalpy is:
1. | Li < Be < B < C < O < N < F < Ne |
2. | Li < Be < B < C < N < O < F < Ne |
3. | Li < B < Be < C < O < N < F < Ne |
4. | Li < B < Be < C < N < O < F < Ne |
Assertion (A): | Generally, ionisation enthalpy increases from left to right in a period. |
Reason (R): | When successive electrons are added to the orbitals in the same principal quantum level, the shielding effect of inner core of electrons does not increase very much to compensate for the increased attraction of the electron to the nucleus. |
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. |
1. | X is an alkali metal and Y is an alkaline earth metal. |
2. | X is an alkaline earth metal and Y is an alkali metal. |
3. | Both X and Y are alkali metals. |
4. | Both X and Y are alkaline earth metals. |
The element having a greatest difference between its first and second ionization energies, is:
1. Ca
2. Sc
3. K
4. Ba