Answer:
No, it's not there.
Explanation:
For a machine to be 100% efficient, it has to be with an output which is equal to its input. But machines have an out put less than an input, hence efficiency below 100%.
The answer is C (the same number of valence electrons)
92 grams of Y would combine with 46 grams of X
The energy added here is potential energy since it is moving upward 180 meters in a gravitational field. This is then turned into KE when it rolls down. 2524N x 180m = 454,320J