Questions

The default return value from a function is int. In other words, unless explicitly specified the default return value by compiler would be integer value from function.

Electronegativity is the tendency for an atom to attract electrons. There are general trends on the periodic table which you can use to determine the relative electronegativity for different elements, but otherwise you can also look at their valence shell and effective nuclear charge to determine their relative electronegativity.

Here from the given options, Lithium has least tendency to attract electrons and thus has a lower electronegativity.

A salary is best described as a fixed amount of income that is paid to an individual on a weekly, bi-weekly or monthly basis.

A salary can also be described as the annual earnings paid out over a year.