Which property is conserved in both nuclear reactions and chemical reactions
O A Total mass of atoms
B Total number of protons and neutrons
O C Number of atoms
O D. Type of atoms

How does the image distance (di) of a convex lens compare with the image distance of a concave lens? a. the image distance of the convex lens is positive, and that of the concave lens is negative. b. both are negative for a virtual image. c. both are positive for a virtual image d. the image distance of the convex lens is negative, and that of the concave lens is positive.

If it takes a planet 2.8 x 10^8 s to orbit a star with a mass of 6.2 x 10^30 kg what is the average distance between the planet and the star

Examine the equation. 23490th→23088ra+42he what kind of barrier would you need to block the radioactive particles from this reaction? a.a piece of paper b.a sheet of aluminum foil c. a two-inch block of lead d. a solid concrete block