What is common about the elements of a period? select all that apply. they have the same number of electron energy levels. they have similar chemical characteristics. they have similar physical characteristics. they transition from a metal to noble gas.

The correct statements are they have the same number of electron energy levels and they transition from a metal to noble gas.

Explanation:

Elements are arranged in 7 periods and 18 groups in a periodic table.

Elements that are arranged in same group have same number of valence electrons and hence show similar chemical properties.

Elements that are arranged in same period have same number of energy levels. In a periods, first metals come, then non-metals and a period ends with a noble gas always.

Hence, the correct statements are they have the same number of electron energy levels and they transition from a metal to noble gas.

n+h→nh3

we must remember that nitrogen and hydrogen are both diatomic molecules in their standard gas form. this adjusts the equation to

n2+h2→nh3

now we need to adjust coefficients in order to balance the atoms on each side of the equation. currently we have 2 atoms of nitrogen and 2 atoms of hydrogen on the reactant side and 1 atom of nitrogen and 3 atoms of hydrogen on the product side.

we can balance the hydrogens by placing a coefficient of 2 in front of ammonia and a coefficient of 3 in front of the hydrogen.

n2+3h2→2nh3

this gives us 6 hydrogen on each side and coincidentally the nitrogens now equal 2 on each side.

the product of the pressure and volume is also constant