Which element will have the following property in the periodic table 1)Largest atomic size 2) Highest electron affinity 3) lowest ionisation enthalpy in group II 4) gaseous form at room temperature

1) Francium

2) Chlorine

3) Barium

4) Rn, Xe, Kr, Ar, Ne, He, F, Cl, O, N and H

Explanation:

1) The atomic radius increases from the top to the bottom of a given group and decreases from the left hand side of a given period to the right of the period. Therefore looking at the bottom left of the periodic table, the atom with the largest atomic radii is Francium

2) Elements with the highest electron are located at the top right corner of the periodic table, opposite to the location of the elements with the highest atomic radius, however, although Fluorine has the highest electronegativity, Chlorine has the highest electron affinity, due to the repulsion present in the 2-p sub-shell of Fluorine

3) Ionization energies increases from bottom to top of  given group, therefore, the element with the lowest ioniztion energy in group II is the element at the bottom of the group which is Ba or barium

4) The gaseous elements are located at the top and extreme right of the periodic table and includes the elements of group 8A(radon (Rn), xenon (Xe), krypton (Kr), Argon (Ar), Neon (Ne) as well as Fluorine (F), Chlorine (Cl), Oxygen (O), Nitrogen (N), Helium (He) and Hydrogen (H).

- calcium has greater affinity to bond with electron receptors than hydrogen does and hence, it has the ability to replace hydrogen in most of its compounds.

- lithium has 2 valence electrons in the product because it can make only 1 bond with hydrogen. beryllium has 4 valence electrons in the product because it can only make 2 bonds. it has fewer electrons than neon and can react with electron donors. each hydrogen has 2 valence electrons, the same as helium.

- the covalent bond formed between carbon and hydrogen is polar because carbon is more electronegative than hydrogen and it attracts the bonded electron pair closer to itself, thus giving hydrogen a partial positive charge.

- a hydrogen bond is a relatively weak bond that hydrogen atoms make with the electronegative atoms nitrogen, oxygen or fluorine.

so the best choice is a.) 2 calcium (ca) atoms