- Atoms that loss or gain electrons are called ions. There are two types of ions: cations and anions.
- Here, 2+ represents that Calcium (Ca) should gain 2 more electrons so that its number equals to that of protons.
- 3- represents that Nitrogen (N) should loss 3 electrons to equivalent with the number of protons.
- Here, anions are S^2-, P^3-, Se^2-, Br^-.
- While cations are Cr^3+, Ag^+, Li^+, Ba^2+.
- The number of protons of Magnesium (Mg) = 12
- The number of nuetrons of Mg = 12
- The number of electrons of Mg = 12
Hope you could get an idea from here.
Doubt clarification - use comment section.
Density is the ratio of mass to the volume.
The mathematical expression is given as:

Now, density of isooctane = 
Volume = 
Since, 1 gallon = 3.78 L
So, 3.8 gal = 
= 
As, 1 L = 1000 mL
Therefore,
= 
Volume in mL = 
Put the values,


= 
Hence, mass of 3.8 gal of the gasoline is
.
A very disgusting type of lemonade
Explanation:
Both conduction and convection are both forms of heat transfer from one place to another.
- In conduction, there must be contact between two bodies for the process to take place but in convection, the matter moves to transfer heat.
- Conduction mostly occurs in solid substances whereas convection occurs mostly in fluids.
- Heat transfer in conduction is quite slow compared to convection which is much faster.
Example of conduction is heating of iron pot when cooking
Example of convection is the refrigerating system.