The correct order of acid strength is:

1. ${\mathrm{Cl}}_2{\mathrm{O}}_7>{\mathrm{SO}}_2>{\mathrm{P}}_4{\mathrm{O}}_{10}$

2. ${\mathrm{CO}}_2>{\mathrm{N}}_2{\mathrm{O}}_5>{\mathrm{SO}}_3$

3. ${\mathrm{Na}}_2\mathrm{O}>\mathrm{MgO}>{\mathrm{Al}}_2{\mathrm{O}}_3$

4. ${\mathrm{K}}_2\mathrm{O}>\mathrm{CaO}>\mathrm{MgO}$

Which among the following elements is the bridge element?

1. K

2. O

3. Mg

4. Pb

Four successive members of the first-row transition elements are listed below with their atomic numbers. Which one of them is expected to have the highest third ionisation enthalpy?

1. Vanadium (Z = 23)

2. Chromium (Z = 24)

3. Iron (Z = 26)

4. Manganese (Z = 25)

The correct order of decreasing second ionisation enthalpy of Ti(22), V(23), Cr(24) and Mn(25) is:
[2008]

1. Cr > Mn > V > Ti

2. V > Mn > Cr > Ti

3. Mn > Cr > Ti > V

4. Ti > V > Cr > Mn

Transition elements show:

1. variable valency

2. paramagnetism

3. catalytic properties

4. all of these

The transition elements are more metallic than the representative elements because they have:

1. The electrons in d-orbitals

2. Electron pairs in d-orbitals

3. Availability of d-orbitals for bonding

4. Unpaired electrons in metallic orbitals

Which pair has elements containing a same number of electrons in the outermost orbit?

1. N, O

2. Na, Ca

3. As, Bi

4. Pb, Sb

The correct arrangement of increasing order of atomic radius among Na, K, Mg and Rb is 

1. Mg<K<Na<Rb

2. Mg<Na<K<Rb

3. Mg<Na<Rb<K

4. Na<K<Rb<Mg

Which of the following statement is correct with respect to the property of elements with increase in atomic number in carbon family.

1. Their metallic character decreases

2. The stability of +2 oxidation state increases

3. Their ionisation energy increases

4. Their atomic size decreases

The correct order of second ionization potential of carbon, nitrogen, oxygen and fluorine is

1. C > N > O > F

2. O > N > F > C

3. O > F > N > C

4. F > O > N > C