Element 'A' has electronic configuration 2, 7; 'B' has electronic configuration 2, 8, 5 and 'C' has electronic configuration 2, 8, 7. Which two elements will exhibit similar chemical properties?

The amount of energy released when one or more electrons is added to the neutral atom is 

The atomic size from left to right across a perid

The ionization potential across a period

The valence shell of element A contains 3 electrons while the valence shell of element B contains 6 electrons. If A combines with B, the probable chemical formula of the compound 

Maximum electron affinity is possessed by 

Which of the following properties do not match elements of the halogen family?

In the periodic table alkali metals are placed in the group ..........

Which of the following sets of atomic number belong to that of alkali metals?

The total number of electrons present in the first twenty elements of the periodic table is