B) A chemical change because the nail reacts with water/oxygen to create rust (a type of oxide)
Just dived both numbers by two
Well partly yes because air pollution can happen when we burn fossil fuels, it can happen when we use vehicles and household/farming chemicals can cause air pollution so yes it is caused by humans
Depending what’s in front of a mirror
If an element contains 8 electrons, then there would be 6 electrons that will be placed in the 2nd valence shell. Each shell in an atom can only take up a fixed number of electrons. For the first shell, only two electrons can be found. For the second shell, it can hold up to 8 electrons. However, for this case only six electrons can be found since the others are found in the first shell.