Natural sources of light include our sun and other stars, where the source of energy is nuclear energy (recall that the moon does not produce light but merely reflects sunlight), lightning, where the source is electrical, and fire, where the energy source is chemical.
Answer:

Explanation:
Hello.
In this case, since the velocity is computed via the division of the distance traveled by the elapsed time:

The distance is clearly 1743 km and the time is:

Thus, the velocity turns out:

Which is a typical velocity for a plane to allow it be stable when flying.
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Answer:
baking the cake batter
Explanation:
Baking the cake batter will indicate that chemical change has occurred here. What is a chemical change?
- A chemical change is one in which a new kind of matter is formed.
- It is usually accompanied by energy either evolution or absorption of energy in form of heat or light or both.
- The process is irreversible.
- When the batter bakes, a new substance different from the cake mix is obtainable.
- We cannot get back the ingredient from this baked cake. It is impossible.
- This is good indicator of chemical change.