Answer:
The answer is in image see it..
Magnesium nitrate o not react with magnesium sulfate because it cannot displace the ions involved. The cations are the same so they just cancel the charges. If you look at it, even of a reaction occurs the product will still be the same substances.
The rule of three is a way to solve problems of proportionality between three known values and one unknown. <u>This is an operation of finding the fourth term of a proportion knowing the other three</u>.
We can use the rule of three to solve this problem in this way,
500 mL → 6 grams
40 mL → x
This is the same as saying: if in 500 mL there should be 6 grams of agarose powder then in 40 mL how many grams should there be?
So,
→ x = 0.48 g = 480 mg
Then, you need to dissolved 480 mg of agarose powder in 40 mL of water to meet the recipe.