Answer:
Galileo discovered that objects that are more dense, or have more mass, fall at a faster rate than less dense objects, due to this air resistance. A feather and a rubber ball dropped together. Air resistance causes the feather to fall more slowly, while the ball falls more fast.
The atomic mass of an element is the number of times of an atom of that element is heavier than an atom of carbon taken as 12. In simpler way, atomic mass is number of protons present in nucleus of an atom, which is a characteristic of an chemical element and is determines place of the element in the periodic table. Mass number is total number of protons and neutrons. If an uncharged atom looses electron from its outermost shell, it becomes cation, which is positively charged species. Atomic number and mass number do not change if electron goes out of an atom.
Uncharged copper after loosing two electrons is converted to 
which can be represented as follows:
→
Answer is: D. 6.02 x 1023.
Because this is Avogadro constant<span> (the number of </span>constituent particles, in this example atoms of gold<span> that are contained in the </span>amount of substance<span> given by one </span>mole). <span>The </span>mole<span> is the </span>unit of measurement<span> for </span>amount of substance, t<span>he mole is an </span>SI base unit<span>, with the unit symbol </span>mol<span>.</span>
Because diffusion<span> is the process when molecules move to lower or higher concentration, so as the molecules move faster they are going to lower or high concentration faster.</span>
