Answer: c. +4
Explanation:
For formation of a neutral ionic compound, the charges on cation and anion must be balanced. The cation is formed by loss of electrons by metals and anions are formed by gain of electrons by non metals.
Here manganese is having an oxidation state of +4 called as cation and oxygen forms an anion with oxidation state of -2. Thus they combine and their oxidation states are exchanged to give 
which written in simplest whole number ratios to give neutral 
Answer: Option (A) is the correct answer.
Explanation:
An element is defined as a substance that contains atoms of same type.
As copper wire is a substance that is made up of only atoms of copper. And, all these atoms of copper will be the same. Hence, it is an element.
This means that all the atoms of copper will have same number of protons, neutrons and electrons.
Thus, we can conclude that the statement they are all exactly the same best describes the copper atoms.
Answer:
polymerization
Explanation:
Student is explaining the process of formation of a polymer and the process is called polymerization.
Polymer is made up of joining repeating units. The repeating units are called monomers.
Properties of the polymer is determined by the structure of monomer molecule.
For example, consider a well-known polymer Teflon.is made by the polymerization of tetrafluoroethane.
Thus, the student is explaining polymerization.
