Coal contains carbon and other elements. Carbon dioxide forms when coal burns in the presence of oxygen. Which of these is the
best evidence that a chemical reaction occurs when coal burns?
A).Oxygen is present.
B).Coal is made up of more than
one element.
C).A new substance is produced.
D).The shape of the coal changes. Help

The number of neutrons is equal to the atomic number minus the atomic mass. a. true b. false

In vapor-liquid equilibrium in a binary mixture, both components are generally present in both phases. how many degrees of freedom are there for such a system? the reaction between nitrogen and hydrogen to form ammonia occurs in the gas phase. how many degrees of freedom are there for this system? steam and coal react at high temperatures to form hydrogen, carbon monoxide, carbon dioxide, and methane. the following reactions have been suggested as being involved in the chemical transformation:

Magnesium is the limiting reactant in this experiment. calculate the theoretical yield of mgo for each trial. trial 1: trial 2: data mass of empty crucible with lid trial 1: 26.688 trial 2: 26.681 mass of mg metal, crucible, and lid trial 1: 26.994 trial: 2 26.985 mass of mgo, crucible, and lid trial 1: 27.188 trial 2: 27.180