Which of the following trends can be identified on the periodic table?
a) atomic radii increase from left to right across the period
b) ionization energy increases from top to bottom within a family
c) electronegativity decreases from left to right across a period
d) atomic radii increase from top to bottom of a group

D) atomic radii increase from top to bottom of a group

Explanation:

Atomic radii trend along group:

As we move down the group atomic radii increased with increase of atomic number. The addition of electron in next level cause the atomic radii to increased. The hold of nucleus on valance shell become weaker because of shielding of electrons thus size of atom increased.

As the size of atom increases the ionization energy from top to bottom also  decreases because it becomes easier to remove the electron because of less nuclear attraction and as more electrons are added the outer electrons becomes more shielded and away from nucleus.

Other options are incorrect because,

A) atomic radii increase from left to right across the period

Correct = atomic radii decreases from left to right across the period

B) ionization energy increases from top to bottom within a family

Correct =  ionization energy decreases from top to bottom within a family

C) electronegativity decreases from left to right across a period

Correct = electronegativity increases from left to right across a period

answer:

the reaction is type of combination reaction.

explanation:

on the product side, there are 2 molecules of bonded to fe   which means one atom of fe are combined two molecules of . so, balanced chemical equation becomes :

this reaction follows the reaction type of combination reaction. a combination reaction is defined as chemical reaction in which reactants combines together to form a single product.