An element's atomic number is 87. how many protons would an atom of this element have

Ais a mountain created from eruptions of lava, ash, rocks, and hot gases.

What best discribes the relationship between wavelength and frequency in a electromagnetic wave

Why does earth rotate? because earth is formed from cold gases collapsing due to gravity because the matter in the nebula that formed earth was spinning because earth forms more than 99% of the mass of the solar system because the hydrogen atoms inside the nebula fused to form helium