<span>Changing atmospheric conditions, like increasing carbon dioxide content, might possibly increase the risk of global warming. Carbon dioxide, along with other greenhouse gases, is one of the leading causes of our Earth's rise in temperature. This is because greenhouse gases trap the planet's heat inside its atmosphere, preventing it from leaving the Earth's surface. </span>
A) 10.0g of Iron is

of Iron.
One mole of dihydrogen is required to form one mole of iron, hence you'll need

of dihydrogen.
B) Likewise : 2.50g of Iron is

of Iron, hence we'll need

of Fe2O3.
In a way, all of the answers could be argued for (for example: in the first option: if the scientists' opinions are understood to be "informed understanding of the causes of events"), but one of the options is the best:
Scientific laws describe specific relationships in nature without offering
an explanation.
The reason why I think this is true is that many laws are phased too short and too concise to provide comprehensive explanations, instead they describe the relationships that must hold.
One of the options is pplain false:
Scientific laws explain why natural events occur. -"Scientific laws were theories that have been tested, proven, and adopted as laws." - since they are not adopted as laws.
Mg(OH)2
Mg: 1
O: 2
H: 2
Mg. O H
24.3g 32g. 2
58.3g in 1 mol of Mg(OH)2
3.2mol of Mg(OH)2 x 58.3g of Mg(OH)2
-------------------------
1 mol of Mg(OH)2
= 186.56 g of Mg(OH)2 in 3.2 mols of Mg(OH)2