The three subatomic particles are proton, neutron and electron. Proton and neutron are present inside the nucleus where as the electrons are present revolving in the orbits around the nucleus. Isotopes of the same element have same atomic number but different number of neutrons. Similarly, ions of an element have different number of electrons. For example, neutral Ag atom has 47 electrons, where as 
ion has 46 electrons. Atomic number which is the number of protons is unique for an element. So the number of protons would remain same for different atoms of same element Ag.
The answer is 3/4.
The coefficient next to each reactant represents the amount of moles. The compound for oxygen is O2 and the compound for aluminum is 4. We can see that the number next to O2 is 3 and the number next to aluminum is 4.
Question 4 is C. 13 I believe
Answer:
D
Explanation:
There are 2 Fe on the left so there must be two on the right.
There are 2 Aluminum on the right so there must be 2 on the left.
Mixtures are classified as homogeneous and heterogeneous according to the distribution of the components of the mixture. If the components are uniformly distributed in the mixture resulting to uniform properties, then it is a homogeneous mixture. However, if it is not uniformly distributed where the composition of one part of the mixture is not the same as other parts, then it is classified as an homogeneous mixture.
