What is the mass number of an atom that has 12 neutrons and 11 protons?

Which explanation is true about what happens to a ray of light when it strikes a mirror? a. a light ray is transmitted toward a mirror at a certain angle. the light ray is then reflected by the mirror at an equal angle but in the opposite direction of the transmitted ray. b. an incident ray strikes a mirror at an angle with a line perpendicular to the mirror. the light ray is then reflected at an angle equal to the angle of incidence but on the opposite side of the perpendicular line. c. a reflecting ray strikes a mirror at an angle with a line perpendicular to the mirror. the light ray is then refracted at an angle equal to the angle of the reflecting ray and on the same side of the perpendicular line. d. an incident ray strikes a mirror at an angle with a line parallel to the mirror. the light ray is then transmitted at an angle equal to the angle of incidence but on the opposite side of the parallel line. you so much! : -d take the time to try and answer correctly.

An alloy contains 66 g of pure zinc. what is the percentage of zinc in the alloy? express your answer to two significant figures and include the appropriate units.

Acetylene gas c2h2 undergoes combustion to produce carbon dioxide and water vapor how many grams of water are produced by the same amount of c2h2?