1) <span> What is heat? the answer is B because heat is a form of energy</span>
Answer:
1) 341 Hz
Explanation:
When a string vibrates, it can vibrate with different frequencies, corresponding to different modes of oscillations.
The fundamental frequency is the lowest possible frequency at which the string can vibrate: this occurs when the string oscillate in one segment only.
If the string oscillates in n segments, we say that it is the n-th mode of vibration, or n-th harmonic.
The frequency of the n-th harmonic is given by

where
n is the number of the harmonic
is the fundamental frequency
Here we have:
is the frequency of the 3rd harmonic
So the fundamental frequency is

And so, the frequency of the 2nd harmonic is:

When light passes from a faster medium into a slower medium, light will be refracted toward a line drawn perpendicular to the point of refraction. <em>(B)</em>
The north celestial pole (and also the south) are described as two imaginary points that project on the axis of rotation of the earth, indefinitely towards space and that intersects with the celestial sphere (Remember that the earth has a slight inclination with respect to to its axis of rotation). The north and south celestial poles are directly above the head of someone located at the north or south pole of the earth.
Correct Answer is A.
I think that it is a mixture because air can contain anything.