The first one is C. Hope this helps!! If you need anymore help just message me and I will try to get back to you quickly and help in any way i can!
Answer:
A
Explanation:
E. An ocean wave moving through water is an example of a mechanical wave
e.g sound waves wave on a rope or string
and Ans a is also correct
It makes calculations with very large and small numbers easier.
Scientific notation is a system used in order to It makes calculations with very large and small numbers easier. It is useful as it allows very large number that would take a lot of space to write otherwise, and it allows them to be calculated easier. 
for example is a incredible large number, but written in this form is immediately understandable and useful for calculation.
Answer:
Complete Circuit
Explanation:
A circuit is defined as a completed path for voltage to flow from a source of voltage through a load and back to the source. A complete circuit or path is often referred to as a(n) ? circuit. Before current can flow in a circuit, the circuit must be closed. 100% right
