Which of the following is the correct electron dot structure for chlorine (atomic no. = 17)?

What produces the 21-cm line that we use to map out the Milky Way Galaxy?

A) atomic hydrogen B) ionized hydrogen C) molecular hydrogen D) carbon monoxide E) helium

A 1024 Hz tuning fork is dangled at the end of a string such that its center of mass is 1.2 m below the point at which the other end of the string is attached to door frame, making a pendulum of sorts. The tuning fork may be treated as a point mass for the purposes of this problem. If the pendulum is brought to a maximum angle and released. If the range of frequencies heard by an observer standing in the plane of the pendulum's motion is 1020-1028 Hz, what is the angle to which the pendulum was raised? The speed of sound in this case is 340 m/s.

a.
b.
c.
d.
e.

Any main-sequence star over 25 solar masses will probably retain enough matter in its core after its supernova to make a black hole

Indicate whether the statement is true or false

Characteristics of Waves: If a wave has a speed of 362 m/s and a period of 4.17 ms, what is its wavelength?

A. 1510 m B. 1.51 m C. 86.8 m D. 86,800 m E. 0.0115 m