A rock sample contains 1/2 microgram of the parent radioactive isotope U-235 and 1/2 microgram of its daughter isotope Pb-207. If the half-life of this decay is 700 million years, how old is this rock?
A) 1400 million years
B) 2100 million years
C) 700 million years
D) 350 million years
C
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Where will a planet in retrograde motion rise?
A. in the north B. in the east (just like everything else in the sky) C. in the south D. in the west (the opposite of everything else in the sky)
The equilibrium rule applies to
A) vector quantities. B) quantities that are equal in magnitude. C) scalar quantities. D) any kind of quantities.
The acceleration due to gravity is smaller on Mars than the Earth, so the Mars rovers that explore the surface are lighter on Mars than they are on Earth. If the rovers roll across a flat plain, then the force required to accelerate the rovers is
A. more than would be required on Earth. B. less than would be required on Earth. C. the same as would be required on Earth.
A temperature of degrees 250 Celsius is equivalent to _____ degrees Fahrenheit
a. –9.4 b. 482.0 c. 121.1 d. –23.0