What do all atoms of an element have in common? what number can be different and allow the atom to still be the same element

the solar system used to have much dust particles option no d

a pan containing water is placed in a positio n where it is exposed to a 10 mile per hour wind. the pan contains a uniform depth of 1.27 cm of water, is quite wide, and has a length of 2.44 m in the wind direction. the water in the pan is at a constant temperature of 15.5 °c.