Classification of Elements and Periodicity in Properties

Ionic radii are

1. inversely proportional to effective nuclear charge
2. inversely proportional to square of effective nuclear charge
3. directly proportional to effective nuclear charge
4. directly proportional to square of effective nuclear charge.

The ions O2-, F-, Na+, Mg2+ and Al3+ are isoelectronic. Their ionic radii show

1. a significant increase from O2- to Al3+
2. a significant decrease from O2- to Al3+
3. an increase from O2- to F- and then decrease from Na+ to Al3+
4. a decrease from O2- to F- and then increase from Na+ to Al3+

Which of the following is isoelectronic?

1. CO2, NO2
2. NO2-, CO2
3. CN-, CO
4. SO2, CO2

Which of the following order is wrong?

1. NH3 < PH3 < AsH3 – acidic
2. Li < Be < B < C – 1st IP
3. Al2O3 < MgO < Na2O < K2O – basic
4. Li+ < Na+ < K+ < Cs+ – ionic radius

An atom has electronic configuration 1s2 2s2 2p6 3s2 3p6 3d3 4s2, you will place it in which group?

1. fifth
2. fifteenth
3. second
4. third

Correct order of 1st ionization potential among following elements Be, B, C, N, O is

1. B < Be < C < O < N
2. B < Be < C < N < O
3. Be < B < C < N < O
4. Be < B < C < O < N