Answer:
Frequency doubles.
Explanation:
Frequency doubles because Wavelength and Frequency are inversely proportional. That means if one decreases the other one increases. So, if wavelength is half, frequency is the opposite, doubles.
Answer:
3
Explanation:
The half-life of a radioactive isotope is the time it takes for the mass of the sample to halve.
This can be rewritten as follows:

where
m(t) is the mass of the sample at time t
m0 is the original mass of the sample
n is the number of half-lives that passed
We see that if we take n=3, the amount of original sample left is

So 3 (3 half-lives) is the correct answer.
Seismic waves are waves generated by Earthquakes.
Answer:
1)Observe a phenomenon
2)Ask a question/ start inferring
3)Form a hypothesis
4)Create an experiment
5)Collect data
6)Compare results
7)Analyze
8)Report findings
9)Compare with other experiments