Answer: 3.024 g grams of hydrogen are needed to convert 76 grams of chromium(III) oxide, 
Explanation:
The reaction equation for given reaction is as follows.
Here, 1 mole of reacts with 3 moles of 
.
As mass of chromium (III) oxide is given as 76 g and molar mass of chromium (III) oxide 
is 152 g/mol.
Number of moles is the mass of substance divided by its molar mass. So, moles of is calculated as follows.
Now, moles of .given by 0.5 mol of is calculated as follows.
As molar mass of is 2.016 g/mol. Therefore, mass of is calculated as follows.
Thus, we can conclude that 3.024 g grams of hydrogen are needed to convert 76 grams of chromium(III) oxide, .
Answer:
The size of an isolated atom can't be measured because we can't determine the location of the electrons that surround the nucleus. We can estimate the size of an atom, however, by assuming that the radius of an atom is half the distance between adjacent atoms in a solid. This technique is best suited to elements that are metals, which form solids composed of extended planes of atoms of that element. The results of these measurements are therefore often known as metallic radii.
.Explanation:
