Is turning the lights off a physical or a chemical change?

Explain why?

42. What is the source of the electric current produced by a voltaic cell? a spontaneous oxidation-reduction reaction competing salt bridges non-spontaneous reduction at the cathode an imbalance of ion charges

How are speed and velocity related

Thorium-229 is a highly radioactive isotope. Use the chart to determine the half-life of Th-229. A) 7,340 years B) 8 years C) 16 years D) 22,020 years

a chemist is studying an unknown substance he can break it into its elemental only by using chemical means. Based on this observation, how should the unknown substance be classified

Which has more atoms: a 1-g sample of carbon-12 or a 1-g sample of carbon-13? explain?

Hydrogen is a pure substance represented by the chemical symbol h. which of the following best describes hydrogen a. hydrogen is a compound made of only one kind of atom. b. hydrogen is a compound made of two or more kinds of atoms. c.

How to assign oxidation and reduction numbers

How to tell difference between hydrogen gas and oxygen gas?

Why do atoms have different speed

Jose gets up from his seat on the bus to move closer to the front. Just as he begins to walk forward, the bus stops at a light.