Males have a bit of a concave plastron , and females have a flat plastron
True
Explanation:
The statement that when the distance between the balls decreases, the size of arrow increases because it shows the gravitational pull between the two balls which increases is true.
According to Newton's law of universal gravitation:
"The gravitational force of attraction between two bodies is directly proportional to the product of their masses and inversely proportional to the square of their separation".
Mathematically, the law is written as:
F = 
F is the gravitational force
G is the universal gravitational constant
m is the mass of the body
r is the distances between them.
We see that the less the distance between the two bodies the more the gravitational force they have.
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Gravitational force brainly.com/question/1724648
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Diamond Abrasive and Mineral Polisher is the most useful as grains on sandpaper. According to Merriam dictionary diamond abrasive are powdered or crushed diamond used as an abrasive also called diamond powder. While mineral polisher is is a mineral that make or finish work piece through rubbing.