Why are chemical changes considered "unseen"?

What is the refractive index of a medium when the light strikes the medium after traveling through air at an angle of 23.3° and the refracted angle is 14.6°?

Which of the following would result in a chemical change

Which example illustrates a chemical change?

What best describes a possible transfer of energy?

While chopping down his father's cherry tree, george discovered that if he swung the axe with a speed of 25 m/s, it would embed itself 2.3 cm into the tree before coming to a stop. if the axe head had a mass of 2.

Rauol's friend Johnny sets out from his house in the city. His displacement is 900 m 80° North of west. What is the x component of his displacement vector?

What is the relationship between gravity and mass? What is the relationship between gravity and distance?

A person performs 300 j of work over the course of 60 seconds how much power they did required

If you have a 90 V power source with a 30-Ω and 60-Ω resistor in series, what is the voltage drop over the 60-Ω resistor? 30 V 2 V 60 V 90 V

How is thermal energy transferred during convection?