An element in period-3 whose electron affinity is zero.

With reference to the variation of properties in the periodic table, which of the following is generally true?

The electron affinity of the elements in group 1 to 7

An alkaline earth metal 

Which of the following remains unchanged on descending a group in the periodic table?

The non-metallic character of the elements from left to right across the period

The atomic size from left to right across a perid

The electronegativity of an element from left  to right 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