Consider five atoms from the second period : lithium , beryllium , boron , carbon , and nitrogen , which of these elements has the lowest electronegatity

Lithium has the lowest electronegativity.

Explanation:

Electronegativity measures the tendency of an atom to attract the bonding pair of electrons. As we move left to right in a period, the number of shell remains same but the number of electron increases(negative charge increases. Hence, electronegativity also increases.

As Lithium is the left most element in this period. It has the lowest electronegativity value which is equal to 0.98.

hypothesising or postulating