What is the most compelling piece of evidence that suggests that the dinosaurs were made extinct by the impact of an asteroid 65 million years ago?
A) a layer of sediment laid down at that time which is littered with dinosaur fossils
B) dinosaur fossils are found in rock layers older than 65 million years but not younger than 65 million years
C) a layer of sediment laid down at that time which is rich in the element Iridium (Ir), an element common in asteroids but less common on the Earth
D) the crater from this impact can still be seen in the deserts of Arizona
C
You might also like to view...
A 20 turn coil of area 10 cm2 is placed in a magnetic field so that the normal to its area is in the direction of the field. If the field has a value of 0.25 T, what is the total flux through the coil?
A. 0.0
B. 
C. 
D. 
E. 
A proton of mass M rotates with an angular speed of 2 × 106 rad/s in a circle of radius 0.80 m in a cyclotron. What is the orbital angular momentum of the proton? (M = 1.67 × 10-27 kg)
A) 2.1 × 10-21 N-m-s B) 1.1 × 10-20 N-m-s C) 2.9 × 10-21 N-m-s D) 5.3 × 10-21 N-m-s E) 3.9 × 10-21 N-m-s
Any indication of prehistoric life preserved in rock is called
a. a shale. b. a radionuclide. c. a fossil. d. none of these.
An airplane traveling at half the speed of sound emits sound at a frequency of 5 000 Hz. At what frequency does a stationary listener hear the sound as the plane approaches, and after it passes by? Assume the airplane is not flying very high