The % yield of Ca(OH)₂ : 62.98%
<h3>Further eplanation
</h3>
Percent yield is the compare of the amount of product obtained from a reaction with the amount you calculated
General formula:
Percent yield = (Actual yield / theoretical yield )x 100%
An actual yield is the amount of product actually produced by the reaction. A theoretical yield is the amount of product that you calculate from the reaction equation according to the product and reactant coefficients
Reaction
CaO + H₂O ⇒ Ca(OH)₂
mass CaO= 4.2 g
mol CaO(MW=56,0774 g/mol) :

mol Ca(OH)₂ based on mol CaO
mol ratio CaO : Ca(OH)₂,= 1 : 1, so mol Ca(OH)₂ = 0.075
mass Ca(OH)₂(MW=74,093 g/mol) ⇒ theoretical

% yield :

675 nanograms is equivalent to 6.75 × 10-⁴ milligrams.
<h3>How to convert nanograms to milligrams?</h3>
Nanograms is a unit of mass equal to 0.000000001 grams and has a symbol of ng.
On the other hand, milligrams is another unit of mass equal to 0.001grams and has a symbol of mg.
Nanograms and milligrams are both units of mass and can be inter-convertible as follows:
1 nanogram = 1 × 10-⁶ milligram
According to this question, 675 nanograms is equivalent to 675 × 10-⁶ milligrams.
Therefore, 675 nanograms is equivalent to 6.75 × 10-⁴ milligrams.
Learn more about milligrams at: brainly.com/question/20320382
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Answer:
Explanation:
None of the statement is true for both chemical and nuclear reactions. In chemical reactions, mass is always conserved and the type of atoms are also conserved.
Tarnish is Ag2S-silver sulfide and the oxidation state of silver is +1