New substances are formed by chemical reactions. When elements react together to form compounds their atoms join to other atoms using chemical bonds. For example, iron and sulfur react together to form a compound called iron sulfide. Hopefully this will help you decide...
Answer:

Explanation:
Angular acceleration is defined by 
Angular velocity is related to the period by 
Putting all together:

Taking our initial (i) point now and our final (f) point one year later, we would have:



So for our values we have:

Where the minus sign indicates it is decelerating.
Decibel - the decibel is a relative unit of measurement equal to one 10th of a bel
C because it’s not a or B so 50/50 c or d and d is def not the answer so c