According to the doppler effect, which statement is true about a sound as it approaches you and then moves away.
a) as the source approaches you, the sound waves are compressed so the pitch of the noise increases.
b) the pitch of the sound remains the same the entire time, regardless of the direction of the source.
c) as the source moves away from you the sound waves are compressed so the pitch of the noise increases.
d) as the source approaches you, the sound waves are stretched relative to the individual so the pitch of the noise decreases.

For cyclohexane compounds drawn in a chair conformation:   -axial bonds are vertical  -equatorial bonds are parallel to two bonds within the ring.  thus, as i assume the chair conformation is drawn:   -the x group is in an axial position, as are the five other vertical bonds.  -three axial bonds are on the top face of the ring  -the other three axial bonds are on the bottom face  the position of the second substituent on each ring carbon is equatorial.  gauche groups must be on an adjacent carbon such as carbon 6 and carbon 2, and also gauche groups are rotated by 60 degrees relative to each other.  drawing the newman projections for c1–c2 and c1–c6 aids in visualizing the groups that are gauche to the y group on c1.  click this link and watch some academic videos that may you more understand the topic 

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