When a helium balloon rises in the air, it expands. if the volume of the balloon doubles, what happens to the density of the helium inside it?

Can someone plz me and put everything in your own words

What term refers to the initial training given to all new employees?

Layer r contains a well-known index fossil that is 100 million years old. based on this information and the principle of superposition, a. layers t and m are older than 100 million years, and layers x and g are younger than 100 million years. b. layers t, m, x, and g are all older than 100 million years. c. layers t and m are younger than 100 million years, and layers x and g are older than 100 million years.