Answer:
Electric engines have efficiencies of roughly 90% whilst combustion engines about 10% to 30%. This is because combustion engines emit much more heat, which is always energy that is not used as work, and thus increases inefficiency.
Explanation:
Answer:
Positive charge.
Explanation:
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In this case, since elements belonging to groups 1A, 2A and 3A are mostly metals, we infer they have the capacity to lose electrons and therefore they become positively charged.
Some examples may be:

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When wood burns, some of the mass is released as a gas. So if you were to combine the small fraction of ash with the gases released, you would get the mass of the original wood.