The answer is definitely C.) their molecules move at the same average speed
Answer:
2PBr₃ + 3Cl₂ → 2PCl₃ + 3Br₂
2Na + MgCl₂ → 2NaCl + Mg
Explanation:
A balanced chemical equation is a chemical equation that have an equal number of elements of each type on both sides of the equation
Among the given chemical reactions, we have;
2PBr₃ + 3Cl₂ → 2PCl₃ + 3Br₂
In the above reaction;
The number of phosphorus, P, on either side of the equation = 2
The number of bromine atoms, Br, on either side of the equation = 6
The number of chlorine atoms, Cl, on either side of the equation = 6
Therefore, the number of elements in the reactant side and products side of the reaction are equal and the reaction is balanced
The second balanced chemical reaction is 2Na + MgCl₂ → 2NaCl + Mg
In the above reaction, there are two sodium atoms, Na, one magnesium atom and two chlorine atoms on both sides of the reaction, therefore, the reaction is balanced
1) The mass of the continent is 
2) The kinetic energy of the continent is 624 J
3) The speed of the jogger must be 4 m/s
Explanation:
1)
We start by finding the volume of the continent. We have:
is the side
is the depth
So the volume is

We also know that its density is

Therefore, we can find the mass by multiplying volume by density:

2)
The kinetic energy of the continent is given by:

where
is its mass
v = 3.2 cm/year is the speed
We have to convert the speed into m/s. We have:
3.2 cm = 0.032 m

So, the speed is:

So, we can now find the kinetic energy:

3)
Here we have a jogger of mass
m = 78 kg
And the jogger has the same kinetic energy of the continent, so
K = 624 J
The kinetic energy of the jogger is given by

where v is the speed of the jogger.
Solving for v, we find the speed that the jogger must have:

Learn more about kinetic energy:
brainly.com/question/6536722
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