DNA of two species is one of the best evidence to tell us how closely related the two species are.
From britaññica it said time and money. They didn’t have either to switch over from the industrial period and never did. Also from my own person reasoning i think most of the world uses not US customary, so to make stuff more accessible. hope this helps!
Answer: a) 8.2 * 10^-8 N or 82 nN and b) is repulsive
Explanation: To solve this problem we have to use the Coulomb force for two point charged, it is given by:

Replacing the dat we obtain F=82 nN.
The force is repulsive because the points charged have the same sign.
Answer:
The higher the spring constant, the greater the elastic potential energy.
Answer:
C. Takes heat in, does work, and loses energy heat.
Explanation:
Heat engine is a system makes use of thermal energy (heat) to in order to do mechanical work.
This occurs by converting the heat into mechanical energy. This energy is then used to do work.
The key characteristic of a heat engine is that the substance with which work is done by, goes from a higher temperature to a lower temperature.
Hence, it loses heat as it does work.