What is the approximate chemical composition (by mass) with which all stars are born?
A) 3/4 hydrogen, 1/4 helium, no more than about 2% heavier elements
B) half hydrogen and half helium
C) 98% hydrogen, 2% helium
D) 95% hydrogen, 4% helium, no more than 1% heavier elements
A) 3/4 hydrogen, 1/4 helium, no more than about 2% heavier elements
You might also like to view...
A small dust particle of mass 7.90 × 10-6 g is being observed under a magnifying lens. Its position is determined to within 0.0050 mm. (1 y = 3.156 × 107 s, h = 6.626 × 10-34 J ? s)
(a) Find the minimum uncertainty in its velocity implied by the uncertainty in its position. (b) Assuming the dust particle is moving at the speed you just found, how many years would it take for the particle to move 1.0 mm? What will be an ideal response?
In what ways is Earth different from the other terrestrial planets?
A) Its lithosphere is broken into plates that move around. B) It has a much higher percentage of oxygen in its atmosphere. C) Most of its surface is covered with liquid water. D) Life can be found almost everywhere on its surface. E) All of the above are true.
A defining feature of "pseudoscience" is
A) it is wrong. B) it does not use proper scientific methodology. C) Both of the above. D) it is unusual, or odd. E) All of the above.
The volume of water displaced by a floating 20-ton boat is
A) 20 cubic meters. B) the volume of 20 tons of water. C) the volume of the boat. D) depends on the shape of the ship's hull. E) none of the above