When the equation Al + O2? Al2O3 is balanced, the coefficient of Al is
a. 1
b. 2
c. 3
d. 4
d
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Information-carrying nerves are connected to the retina at the
A) fovea. B) blind spot. C) cornea. D) iris. E) periphery.
The only possible geometry of an accelerating universe is open
Indicate whether the statement is true or false
The half-life of cobalt-60 is 5.3 years, while that of strontium-90 is about 29 years
Suppose you have samples of both isotopes, and that they initially contain equal numbers of atoms of these isotopes. How will the activities (number of decays per second) of the samples compare? A) The activities will be equal. B) The activity of the cobalt-60 sample will be greater. C) The activity of the strontium-90 sample will be greater. D) The activities cannot be compared without more information.
When an object is effectively isolated from external torques, like an ice skater twirling on the tip of one skate, the angular momentum of the object
a. can be increased by shifting mass out away from the axis of rotation. b. can be decreased by shifting mass out away from the axis of rotation. c. can be increased by shifting mass in toward the axis of rotation. d. can be decreased by shifting mass in toward the axis of rotation. e. cannot be changed except by friction at the point of contact.