Answer:
HF is the limiting reactant
Explanation:
The balanced equation for the reaction is given below:
SiO₂ + 4HF —> SiF₄ + 2H₂O
From the balanced equation above,
1 mole of SiO₂ reacted with 4 moles of HF.
Finally, we shall determine the limiting reactant. This can be obtained as illustrated below:
From the balanced equation above,
1 mole of SiO₂ reacted with 4 moles of HF.
Therefore, 7.5 moles of SiO₂ will react with = 7.5 × 4 = 30 moles of HF.
From the calculation made above, we can see clearly that it will take a higher amount (i.e 30 moles) of HF than what was given from the question (i.e 5 moles) to react completely with 7.5 moles of SiO₂.
Therefore, HF is the limiting reactant and SiO₂ is the excess reactant.
The distance of the earth to the sun in Mm = 1.5 x 10⁵
<h3>Further explanation</h3>
Given
The distance of the earth to the sun : 1.50 x 10⁸ km
Required
The distance in Mm
Solution
In converting units we must pay attention to the conversion factor.
the conversion factor :
1 kilometer(km) = 10⁻³ megameter(Mm)
So the distance conversion :
1.5 x 10⁸ x 10⁻³ = 1.5 x 10⁵ Mm
Earnest Rutherford was JJ Thomson’s student. He disproved Thomson’s plum pudding model. So Rutherford comes after Thomson. Dalton is first because you should be aware of Daltons atomic theory on the atom. He was one of the first people to actually make a theory about atoms in that type of detail. Bohr came last. I forgot what Bohr’s model was, but you can do a quick google search if you want.
So your answer is B, the second one
