Its doesn't dissolve in water!
Answer : The mass of the water in two significant figures is, 
Explanation :
In this case the heat given by the hot body is equal to the heat taken by the cold body.


where,
= specific heat of iron metal = 
= specific heat of water = 
= mass of iron metal = 32.3 g
= mass of water = ?
= final temperature of mixture = 
= initial temperature of iron metal = 
= initial temperature of water = 
Now put all the given values in the above formula, we get


Therefore, the mass of the water in two significant figures is, 
The answer to your question is B.
<h3>
<u>Answer</u></h3>
4. loses 2 electrons
<h3>
<u>EXPLANATION</u></h3>
Mg²+ has 10 electrons while Mg has 12 electrons.