The trend of atomic radius in a period and a group is :
1.
Generally decreases from right to left across a period and increases down a group.
2.
Generally increases from left to right across a period and decreases down a group.
3.
Generally decreases from left to right across a period and increases down a group.
4.
Generally remains same from left to right across a period and increases down a group.
Anions are larger in radius than their parent atoms because:
| 1. | An anion has a fewer number of electrons than its parent atom |
| 2. | An anion has the same number of electrons as its parent atom. |
| 3. | An anion has a higher effective nuclear charge. |
| 4. | An anion has more electrons than its parent atom |
The energy of an electron in the ground state of the hydrogen atom is . The ionization enthalpy of atomic hydrogen in terms of J is:
1. 2.81 × 106 J mol
2. 1.31 × 106 J mol
3. 2.31 × 106 J mol
4. 1.81 × 106 J mol
The explanation for the fact that the first ionization enthalpy of sodium is lower than that of magnesium but its second ionization enthalpy is higher than that of magnesium would be :
| 1. | Pressure and volume |
| 2. | Lustre and brightness |
| 3. | Atomic size and effective nuclear charge |
| 4. | Availability in nature |
The ionization enthalpy of the main group elements tends to decrease down a group due to,
1) Increase in the atomic size of elements and increase in the shielding effect
2) Decrease in the atomic size of elements and increase in the shielding effect
3) Increase in the atomic size of elements and decrease in the shielding effect
4) Decrease in the atomic size of elements and decrease in the shielding effect
The first ionization enthalpy values (in kJ mol–1) of group 13 elements are :
| B | Al | Ga | In | Tl |
| 801 | 577 | 579 | 558 | 589 |
The explanation for the deviation from the general trend can be -
1. Ga has lower ionization enthalpy than Al.
2. Ga has higher ionization enthalpy than Al.
3. Al has higher ionization enthalpy than Ga.
4. Ga has a lesser valence electron than Al.
An element with higher negative electron gain enthalpy in the given pair is:
(i) O or F (ii) F or Cl
1. O, Cl
2. F, F
3. O, F
4. F, Cl
The relationship between 1st and 2 nd electron gain enthalpy of oxygen atom (O) would be :
| 1. | Both values of electron gain enthalpy are negative. |
| 2. | The 1st electron gain enthalpy of (O) is negative while 2 nd is positive. |
| 3. | Both values of electron gain enthalpies are positive. |
| 4. | The 1st electron gain enthalpy of (O) is positive while 2 nd is negative. |
The basic difference between the electron gain enthalpy (Ea) and electronegativity (EN) is:
| 1. | Ea is the tendency to lose electrons, while EN is the tendency to repel the shared pairs of electrons. |
| 2. | Ea is the tendency to gain neutrons, while EN is the tendency to attract the shared pairs of electrons. |
| 3. | Ea is the tendency to donate electrons, while EN is the tendency to attract the shared pairs of molecules. |
| 4. | Ea is the tendency to gain electrons, while EN is the tendency to attract the shared pairs of electrons. |
The statement that "the electronegativity of N on the Pauling scale is 3.0 in all the nitrogen compounds" is incorrect because:
| 1. | Electronegativity of an element is a variable property. |
| 2. | Pauling scale is not used to measure electronegativity. |
| 3. | The electronegativity of N on the Pauling scale is 12.0 |
| 4. | None of the above. |
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