The ionization energy boron is less than that of beryllium because :
1. beryllium has a higher nuclear charge than boron
2. beryllium has a lower nuclear charge than boron
3. the outermost electron in boron occupies a 2p-orbital
4. the 2s and 2p-orbitals of boron are degenerate

Select the amphoteric substance in the following :

Which of the following is not a representative element?

1. Tellurium

2. Tantalum

3. Thallium

4. Astatine

Element having highest I.P value is :

1. Ne

2. He

3. Be

4. N

Second electron gain enthalpy :

1. is always negative

2. is always positive

3. can be positive or negative

4. is always zero

To which of the following atom, the attachement of electron is most difficult ?

1. Radon

2. Nitrogen

3. Oxygen

4. Radium

If IUPAC name of an element is "unununium" then correct statement regarding element is:

1. It is a inner transition element

2. It belongs to 8th period in periodic table

3. It is transition element

4. It is a non-transition element

Which of the following graph is correct representation between atomic number (Z) and magnetic moment of d-block elements? [Outer electronic configuration : (n-1)d^xns^{1 or 2}]

The effective nuclear charge at the periphery of chromium atom [Z = 24];

1. 4.25

2. 2.60

3. 3.60

4. 1.21

The least stable cation is :

1. ${\mathrm{Li}}^{+}$ 

2. ${\mathrm{K}}^{+}$

3. ${\mathrm{Al}}^{2+}$

4. ${\mathrm{Si}}^{2+}$