Consider this row in the periodic table of elements. as we move from left to right, across the row, the elements a) change from nonmetals to metals. b) change from metals to nonmetals. c) start as gases but end as solids. d) show a decrease in atomic mass number.

B) change from metals to nonmetals.

The answer is: B) change from metals to nonmetals.

For example, alkaline metals (far left in main group) have lowest ionizations energy and easy remove valence electrons (one electron, earth alkaline metals (right next to alkaline metals) have higher ionization energy than alkaline metals, because they have two valence electrons.

Nonmetals are far right in the main group and they have highest ionization energy, because they have many valence electrons.

Atomic number is the number of protons, which is characteristic of a chemical element. Atomic number increases from left to right in Periodic table.

the equation that correctly represent the reaction for formation of ammonia is

n2+ 3h2 → 2nh3 (answer d)

1 mole of nitrogen gas (n2) react with 3 moles of hydrogen gas (h2) to form 2 moles of ammonia ( nh3). this is in a process known as haber process were iron is used as a catalyst and reaction take place that a higher temperature and pressure. the process is exothermic hence energy is released.