<h2>
Answer:</h2>
The reaction is <u>D. endothermic</u>.
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Explanation:</h2>
Absorption or need of energy from surroundings is called endothermic process. Heat is the major common form of energy which is absorbed in this process. In this process, enthaply of reactant is less than the product.
For example, an ice cube placed in the hand for some time starts to melt and it takes energy in the form of heat from the hand. This process always requires energy because of the breaking of existing and formation of new chemical bonds.
Answer:
Galileo
Explanation:
Galileo Galilei pioneered the experimental scientific method, and was the first to use a refracting telescope to make important astronomical discoveries. He is often referred to as the "father of modern astronomy" and the "father of modern physics". Albert Einstein called Galileo the "father of modern science."
Answer:
a) Zero
b) power source
Explanation:
According to Ohm's law, the voltage dropped in a resistance is proportional to the current flow and the resistor opposing to it.

For the case of a short circuit, the resistance tends to zero, so the voltage will tend to zero too.
In the case of the open circuit, the resitance will tend to infinity, because we cannot obtain an infite voltage, it will be limited by the power source.