The rate of the nuclear reaction in a power plant reactor is controlled by rods that
a cool the reactor core
b. heat water circulating around the fuel rods
c. change the concentration of uranium
d. absorb free neutrons

Mass = 0.014 g

Explanation:

Given data:

Mass of HCl = 0.500 g

Mass of hydrogen gas produced = ?

Solution:

Chemical equation:

Zn + 2HCl       →      ZnCl₂ + H₂

Number of mole of HCl :

Number of moles = mass/molar mass

Number of moles = 0.500 g / 36.5 g/mol

Number of moles = 0.014 mol

Now we will compare the moles of HCl with hydrogen.

            HCl           :            H₂

              2             :            1

           0.014         :           1/2×0.014 = 0.007

Mass of hydrogen gas:

Mass = number of moles × molar mass

Mass =  0.007 mol × 2 g/mol

Mass = 0.014 g