<u>Answer:</u> The spacing between the crystal planes is 
<u>Explanation:</u>
To calculate the spacing between the crystal planes, we use the equation given by Bragg, which is:

where,
n = order of diffraction = 2
= wavelength of the light =
(Conversion factor:
)
d = spacing between the crystal planes = ?
= angle of diffraction = 22.20°
Putting values in above equation, we get:

Hence, the spacing between the crystal planes is 
Answer:
D
Explanation:
They are renewable energy sources
Answer:
72.6 grams
Explanation:
I got this answer through stoichiometry. For every 1 mole of Mg, 2 moles of CuBr are consumed. Because of this, multiply the moles of Mg by 2. Then, convert moles to grams.
Electronegativity is a measure of an atom's ability to attract shared electrons to itself. On the periodic table, electronegativity generally increases as you move from left to right across a period and decreases as you move down a group.
The reaction will be: FeBr2 + K --> KBr + Fe
Balancing gives: FeBr2 + 2K --> 2KBr + Fe
The molar mass of FeBr2 is 55.85 + 2*79.9 = 215.65 g/mol.
We divide 40 g / 215.65 g/mol = 0.185 mol FeBr2
Based on stoichiometry:
(0.185 mol FeBr2)(2 mol KBr/1 mol FeBr2) = 0.370 mol KBr