How many protons neutrons and electrons are present in the following atoms A)15N7
B)60Co27
C)131I53
D)207Pb82

Nebulae are enormous clouds in outer space. they are made mostly of hydrogen gas, helium gas, and dust. some nebulae glow brightly, while others do not. the stars that people see are huge, bright balls of glowing gas. they are made mostly of hydrogen and helium. which statement correctly describes other ways in which nebulae and stars are different? a. stars can form inside a nebula but a nebula can never be produced by any star. b. a star always has a higher density than a nebula. c. stars can never form inside a nebula but a nebula can be produced by any star. d. a nebula always has a higher density than a star.

Which are forms of frozen water? check all that apply. dew frost hail rain sleet

The identities of substances are the same before and after which type of change