Can someone please solve this for me and explain it

83.3% yield

Explanation:

First, we need to convert 240 g of into moles:

Next, find the theoretical Fe yield using molar ratios.

Then convert this back into grams:

Note that actual yield is only 140 g Fe so percentage yield is

%= 83.3%

we can conclude that the melting point of table salt is above room temperature (it's actually 801 deg c). the melting point of mercury must be below room temperature (- 39 deg c).