Answer:
Gravity
Explanation:
Without gravity it would just float in space.
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Answer:
4th line
Explanation:
-water cycle helps regulate the temperature on the Earth.
Answer: The correct option is 2.
Explanation: There are two types of nuclear reactions:
1) Nuclear fission: These reactions are defined as the reactions in which a heavier unstable nuclei breaks into two or more smaller stable nuclei.
2) Nuclear fusion: These reactions are the ones where two smaller nuclei fuse together or combine together to form a larger nuclei.
In the question, we need to find the fusion reaction which forms elements heavier than helium.
Option 1: In this fusion reaction occurs but the nuclei is Helium itself.
Option 2: In this also fusion reaction occurs and the nuclei is heavier than Helium which is Neon.

Option 3 and Option 4: These two reactions are nuclear fission reactions of Uranium-235 because one heavier element is breaking into more than 2 products.
Hence, the correct option is 2.
Answer:
C. To determine how efficient reactions are.
D. To determine how much reactant they need.
Explanation:
When you are doing a reaction, you are hoping for a percent yield to close of 100%. You make the reaction and determine how many product you obtain. If you know the percent yield of a reaction you can calculate the amount of reactant you need to obtain a determined amount of product.
Having this in mind:
A. To balance the reaction equation. false. To calculate percent yield you need to balance the reaction before. You don't use percent yield to balance the reaction
B. To determine how much product they will need. false. You determine how much product you obtain after the reaction. How much product you need is independent of percent yield
C. To determine how efficient reactions are. true. A way to determine efficience of a reaction is with percent yield. An efficient reaction has a high percent yield.
D. To determine how much reactant they need. true. If you know percent yield of a reaction you can know how many reactant you must add to obtain the amount of product you want.
Answer:
Conduction, Convection, and Radiation
Explanation:
Kinetic energy is the energy a body possesses by being in motion. Kinetic energy takes place when the air inside the balloon gets exposed to heat. The hot air rises which will create and fill the shape of the balloon and allows it to move. Heat energy, also known as thermal energy occurs.