Answer question number 3

Use a magnet to remove the fillings.

Explanation:

This is a mixture not a solution, maening it can be seperated. Since the substance mixed with water is iron fillings, it can be removed from the mixture  using a magnet. Also, salt can be seperated by water by being boiled, it evaporates and leaves behing crystalized sodium particles.

atomic number of carbon is 6

electronic configuration of carbon is 1s²2s²2p²

orbital diagram of carbon is as shown here in the image.

the density(ratio between mass and volume as m/v) decreases from top to bottom in periodic table group as the size increases and nuclear charge decreases. but in periods density increases from left to right as atom size decreases and nuclear charge increases.