I don´t understand any of this!!

Anurse used a 0.02-mg/l solution of disinfection to clean a patients wound. what is the concentration of the solution expressed as a percentage?

Some familiar products contain some of the same types of atoms. for instance, the chemical formula for baking soda is nahco 3. the chemical formula for liquid bleach is naclo, and the chemical formula for table salt is nacl. which choice best describes why these three products have some of the same types of atoms in common?

What is the correct lewis dot structure for arsenic?