Which of the following is an example of a covalent bond?
A-H2o
B-NaCi
C-MgO

Electoral current force mechanical advantage if the wheel and axle is 2 n and the output force is 20 n

Aform of energy that is reflected or emitted from objects in the form of electrical and magnetic waves that can travel through space. there are many forms of  electromagnetic  energy including gamma rays, x rays, ultraviolet radiation, visible light, infrared radiation, microwaves and radio waves.

The answer should be a.