Answer:
Oil
Explanation:
Since, unlike oil, source like wind, solar, water etc. come naturally we don't and can't replace them but when the viscosity in oil has been used up it must be change to allow the proper functioning of the machine.
<u>Answer:</u> The weight of the person above the surface of a planet is 635.83N.
<u>Explanation:</u>
To calculate the weight of a person, we use the formula:
....(1)
where,
w = weight of an object
m = mass of the person = 65kg
g = acceleration due to the gravity of the planet
For the calculation of weight, we need to first find the acceleration due to gravity and for that we use the formula:

where, g = acceleration due to gravity = 
G = Universal gravitational constant = 
M = mass of the planet = 
r = distance of the person from the planet = 
Putting values in above equation, we get:

Putting this value in equation 1, we get:

Hence, the weight of the person above the surface of a planet is 635.83N.
<u><em>Answer:</em></u>
<u><em>The correct option is </em></u><u><em>A</em></u>
Explanation:
The main adaptation of desert plants is to minimize water loss through their pores and also through the cell walls on their leaves. So the leaves of many desert plants have a thick covering that is coated with a waxy substance that allows them to seal in and protect what moisture they already have.
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