Answer:
Hot material near Earth's surface is more dense and sinks, and when it cools, it becomes less dense and rises.
Explanation:
Convection is a process by which less dense material rises and more dense material sinks near Earth's surface. Water, air, rocks and other materials expands when temperature rises and they become less dense. When the water is heated it becomes vapors and carries away thermal energy from the water.
It would be a positive charge because it lost two electrons, if the charge was neutral it would be the same amount of protons and electrons, if the charge was negative the electrons would be 20 instead of 18. So in this case it is positive.
Which of the following measurements is expressed to three significant figures?
C. 5.60 km
Hope this helps!
Answer:
That iron atom is oxidized. It loses two electrons.
Explanation:
Compare the formula of an iron atom and an iron(II) ion:
- Iron atom:
; - Iron(II) ion:
.
The superscript 
in the iron(II) ion is the only difference between the two formulas. This superscript indicates a charge of on each ion. Atoms and ions contain protons. In many cases, they also contain electrons. Each proton carries a positive charge of 
and each electron carries a charge of 
. Atoms are neutral for they contain an equal number of protons and electrons.
Protons are located at the center of atoms inside the nuclei. They cannot be gained or lost in chemical reactions. However, electrons are outside the nuclei and can be gained or lost. When an atom loses one or more electrons, it will carry more positive charge than negative charge. It will becomes a positive ion. Conversely, when an atom gains one or more electrons, it becomes a negative ion.
An iron atom will need to lose two electrons to become a positive iron(II) ion with a charge of on each ion. That is:
.
- Oxidation is Losing one or more electrons;
- Reduction is Gaining one or more electrons.
This definition can be written as the acronym OILRIG. (Khan Academy.)
In this case, each iron atom loses two electrons. Therefore the iron atoms here are oxidized.
The balanced equation is attached in the image below. The coefficients are 2, 2, blank.
