How many moles of oxygen gas (O2) are required to completely react with 10 moles of hydrogen gas (H2)?

5 moles of oxygen are required.

Explanation:

Given data:

Moles of O₂ required = ?

Moles of H₂ present = 10 mol

Solution:

Chemical equation:

O₂ + 2H₂       →     2H₂O

Now we will compare the moles of oxygen and hydrogen.

                      H₂        :        O₂

                        2         :         1

                       10         :     1/2×10 = 5 mol

5 moles of oxygen are required.

the density(ratio between mass and volume as m/v) decreases from top to bottom in periodic table group as the size increases and nuclear charge decreases. but in periods density increases from left to right as atom size decreases and nuclear charge increases.