Answer: 
Explanation:
According to the law of conservation of mass, mass can neither be created nor be destroyed. Thus the mass of products has to be equal to the mass of reactants. The number of atoms of each element has to be same on reactant and product side. Thus chemical equations are balanced.
The balanced equation will be:

Answer:
Ocean Currents
Explanation:
The correct answer is Ocean currents.
When the earth receives solar radiation, a large fraction of this incident radiation is usually absorbed by the oceans and the seas, which become warm. Usually, equitorial regions are the ones that have this phenomenon. Now, when ocean currents are flowing from the equator, they usually carry this warm water with them thereby moving the greatest amount of heat from the equator on its way out.
For example, In the Pacific Ocean, there is a current known as Alaska Current that carries warm water in the northward direction thereby making Anchorage which is Alaska's largest city to have a much mild weather than the inland areas with the same latitude.
Answer: A
Explanation: Protons and neutrons form the nucleus of the atom, with electrons orbiting it.
<u>Answer:</u> The given example is a physical change.
<u>Explanation:</u>
A chemical change is defined as the change in which chemical composition of a substance changes and results in the formation of a new substance. These are usually irreversible process.
A physical change is defined as the change in which only the shape and size of the substance changes and no new substance is formed. Only phase change occurs in these processes. These are usually considered as a reversible change.
For the given example: Moisture in the air forms beads of water on a cold window pane.
This is a physical change because water was initially present in the gaseous state (Moisture in the air) and when it is coming in contact with the cold window pane, the gaseous state of water gets converted into a liquid state.
Hence, the given example is a physical change.