Cecil writes the equation for the reaction of hydrogen and oxygen below.
h2 o2 → h2o
why does his teacher ask him to balance the equation by including the correct coefficients?

The gun from the crime scene shows tool marks where the serial numbers are ground off. there are also tool marks on the bullets left behind. what information can the tool marks on the bullets and gun provide about the crime? what type of evidence does this information provide, individual or class?