It is commonly known that our Galaxy rotates upon the sun because of gravity. The diagrams' arrows sort of describe it. Id suggest Gravity as the answer.
Answer:

Explanation:
The formula for efficiency is

Data:
Useful energy = 3 J
Energy input = 30 J
Calculation:

Answer:
4.75 moles of Fe
Explanation:
We'll begin by writing the balanced equation for the reaction. This is given below:
FeO + CO —> Fe + CO2
Now, we can determine the number of mole of iron, Fe produced by the reaction of 4.75 mol of FeO with excess CO as follow:
From the balanced equation above,
1 mole of FeO reacted to produce 1 mole of Fe.
Therefore, 4.75 moles of FeO will also react to produce 4.75 moles of Fe.
Therefore, 4.75 moles of Fe is produced.
Answer:
Keep temperature constant and increase the pressure of the reaction. The rate of reaction increases.
Explanation:
First of all, the question is asking us to design an experiment to investigate the effect of pressure on the rate of reaction hence the pressure can not be held constant since it is the variable under investigation. This eliminates the first option.
Secondly, increasing the pressure of the reaction means that particles of the gas collide more frequently leading to a greater number of effective collisions and a consequent increase in the rate of reaction according to the collision theory.
Hence the answer above.