Answer:
Radio waves are a type of electromagnetic radiation with wavelengths in the electromagnetic spectrum longer than infrared light. They have frequencies from 300 GHz to as low as 3 kHz, and corresponding wavelengths from 1 millimeter to 100 kilometers.
Explanation:
Answer:
Option (A) and (F)
Explanation:
As the liquid cools down, it means the temperature decreases the density of the liquid increases in most o the cases.
Now the volume is inversely proportional to the density of substance so density increases.
Answer:
a) 
b) 
Explanation:
Part a
For this case we can begin finding the period like this:

Then we know that the centripetal acceleration is given by:

And the velocity is given by:

If we replace this into the acceleration we got:

And we can replace the values and we got:

Part b
For this case we want to find a value of k such that:

Where a = 9.74, so then we can solve for k like this:

The interstellar medium is the matter as well as the radiations that are found in the galaxies occupying the spaces between the star systems.
Interstellar medium is mainly composed of hydrogen that is followed by helium and trace amounts of nitrogen, oxygen and carbon (considered traces when compared to amount of hydrogen).
Therefor, the right choice is:
<span>A. Water, Carbon dioxide, and Hydrogen</span>