Answer:
d. 127 g/mol.
Explanation:
Hello!
In this case, since we have the amount of molecules of this this compound, we are able to compute the moles out there by using the Avogadro's number:

Which correspond to the moles of X2. Then, by using the mass we are able to compute the molar mass of X2:

It means that the atomic mass of X halves the molar mass of X2, which is then d. 127 g/mol.
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B. When scientific understanding changes.
Answer:
Explanation:
Enertia is an integral part of Newton's first law of motion.
It is the tendency of an object to <u>stay at rest</u> or <u>to continue moving</u> until and unless <u>any external unbalanced force</u>, (like, applied force or force of tension or frictional force ) is applied to either move it from rest or change its speed(in other words, accelerate it!!).
Example below, is of ball at rest (fig1) and if this ball is moving straight on a frictionless surface(like ice) it will keep moving!! until, we push it or pull it.
With the info given i would have to say their is no kinetic energy, it's all potential energy.