Which of the following statements about the Modern Periodic Table is correct?

$(a)$ Amongst the following elements,identify the ones that would form anions:
$K, O, Na, F, Ca, Cl, Mg$
$(b)$ Write the electronic configuration of the anions identified above.

Which of the following sets of elements is written in the order of their increasing metallic character?

Which group of elements could be placed in Mendeleev's Periodic Table without disturbing the original order? Give reason.

An element is placed in $2^{nd}$ Group and $3^{rd}$ Period of the Periodic Table. It burns in the presence of oxygen to form a basic oxide.
$(a)$ Write a balanced chemical equation when this oxide is dissolved in water.
$(b)$ Draw the electron dot structure for the formation of this oxide.

$(a)$ Name the element with atomic number $17$.
$(b)$ To which period does it belong?
$(c)$ To which group does it belong?
$(d)$ Write its electronic configuration.