Does anyone know a website where it solves me these types of problems OR if someone can help me with them?

How many grams of rust (Fe2O3) would be produced by the complete reaction of 0.15 grams of iron metal?
4 Fe + 3 O2 -> 2 Fe2 O3

you can use the idea of molecular masses to calculate easily

in chemistry, a solution’s concentration is how much of a dissolvable substance, known as a solute, is mixed with another substance, called the solvent. the standard formula is c = m/v, where c is the concentration, m is the mass of the solute dissolved, and v is the total volume

fe 55.85 g/mol and h2o 18.02 g/mol.