Here is a site my buddie has to help you. Well co-owner..
https://www.quora.com/Why-is-fresly-prepared-FeSO4-required-for-the-ring-test
your answer is going to be (A.)during the little ice age
The concentration of solution : 0.2 M
<h3>Further explanation</h3>
Given
5.6 g Potassium hydroxide(KOH)
500 ml of solution = 0.5 L
Required
The concentration
Solution
Molarity shows the number of moles of solute in every 1 liter of solution or mmol in each ml of solution

MW KOH = 39+16+1=56 g/mol
mol solute(KOH) :
= mass : MW KOH
= 5.6 : 56 g/mol
= 0.1
Molarity :
= 0.1 : 0.5
= 0.2 M
<span>At much higher temperatures, nitrogen reacts with oxygen to form nitric oxide, but this takes a considerable spark of energy. In the upper atmosphere during a lightning storm, nitrogen and oxygen react and the resulting nitric oxide further reacts with water to form nitric acid. When it rains, this nitric acid is carried down to Earth and forms compounds with other elements. Nitrates and nitrites are a few of the results.</span>