A. : In this reaction one of the product, FeS is insoluble. Therefore, this is a precipitation reaction.
B. : In this reaction, the product is a solid(insoluble). So, this is a precipitation reaction too.
C.: In this reaction, both the products are soluble. So this is not a precipitation reaction.
D.: In this reaction, both the products are soluble. So this is not a precipitation reaction.
E. : In this reaction, the product AgCl is a precipitate. So, it is a precipitation reaction.
In chemistry, the molar mass of a chemical compound is defined as the mass of a sample of that compound divided by the amount of substance in that sample, measured in moles.
I think it is 1620 (lxwxh) x 10 to get to millimeters
