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Answer:
A. 
B. 
C. 
Explanation:
Given:
- spring constant,

- mass attached,

A)
for a spring-mass system the frequency is given as:



B)
frequency is given as:



C)
Time period of a simple harmonic motion is given as:


Answer:
In the middle of a dry cell, is a rod made of carbon. Around the carbon rod is a chemical paste. At the same time, the carbon rod becomes positively charged. When this happens, electrical current flows out of the cell when a conductor is attached between the cell's positive and negative terminals.
The answer would be
C. Rods and Cones