What is the definition for chemical change

Manufacturers of headache remedies routinely claim that their own brands are more potent pain relievers than the competing brands. Their way of making the comparison is to compare the number of molecules in the standard dosage.

What is the iodide ion concentration in a solution if the addition of an excess of 0.100 m pb (no3) 2 to 42.9 ml of the solution produces 861.8 mg of pbi2?

A train travels 80 kilometers in 3 hours, and 84 kilometers in 2 hours. What is the average speed?

If the kinetic and potential energy in a system are equal, then the potential energy increases. What happens as a result?

Which of the following statements about a metal wire in equilibrium are true? Select all that apply. There cannot be excess charges on the surface of the wire. There may be excess charges in the interior of the wire.

Both the electrical force and the gravitational force between two objects share which relationship? They are directly proportional to mass. They are inversely proportional to the square of the distance. They are inversely proportional to charge.

During a baseball game, a player hits a a ball with a speed of 43m/s at an angle of 25∘ above the horizontal. When the player hit the ball, it was 1m above the ground, and after the hit, the ball flies straight toward the center field fence.

How does the electric potential energy change as the electron moves from i to f?

A sound wave travels twice as far in neon (Ne) as it does it krypton (Kr) in the same time interval. Both neon and krypton can be treated as monatomic ideal gases. The atomic mass of neon is 20.2 u, and that of krypton is 83.8 u.

A 0.25 kg hockey puck is sliding along the ice with an initial velocity of 5 m/s when a player strikes it with his stick, causing it to reverse its direction and giving it a velocity of 30 m/s.