What is an astronomical unit?
a) the length of time it takes Earth to revolve around the Sun
b) the diameter of Earths orbit around the Sun
c) the average distant from Earth to the Sun
c) the average distant from Earth to the Sun
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The sound level at 1.0 m from a certain talking person talking is 60 dB. You are surrounded by five such people, all 1.0 m from you and all talking equally loud at the same time
The threshold of hearing is 1.0 × 10-12 W/m2. What sound level are you being exposed to? You can neglect any absorption, reflection, or interference of the sound. The threshold of hearing is 1.0 × 10-12 W/m2. A) 300 dB B) 60 dB C) 74 dB D) 67 dB E) 81 dB
What direct evidence do astronomers have that supports the heavy element formation in stars?
A) The presence of technetium in giant star spectra B) Observed elemental abundances C) Gamma-ray emissions from decay of cobalt 56 in supernovae D) Light curves of type-I supernovae E) All of the above are evidence of this.
Of the following, an atom with the atomic number ____ would be the least reactive
a. 1 b. 3 c. 17 d. 18 e. 21
A particular chemical reaction occurs at room temperature (293 K) at half the rate that it does at 300 K. What is the activation energy for this reaction?
a. 
b. 
c. 
d. 