Select the amphoteric substance in the following :

Second electron gain enthalpy :

1. is always negative

2. is always positive

3. can be positive or negative

4. is always zero

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}]

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

1. Radon

2. Nitrogen

3. Oxygen

4. Radium

Which of the following is not a representative element?

1. Tellurium

2. Tantalum

3. Thallium

4. Astatine

The least stable cation is :

1. ${\mathrm{Li}}^{+}$ 

2. ${\mathrm{K}}^{+}$

3. ${\mathrm{Al}}^{2+}$

4. ${\mathrm{Si}}^{2+}$

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

Element having highest I.P value is :

1. Ne

2. He

3. Be

4. N

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

1. 4.25

2. 2.60

3. 3.60

4. 1.21