Which of the following statements is probably true about the very first stars in the universe?
A) They were made only from hydrogen and helium.
B) They were made from pure energy.
C) They were probably orbited only by terrestrial planets, but no jovian planets.
D) They were made approximately of 98% hydrogen and helium, and 2% of heavier elements.
A
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Exclusion Principle: Which of the following values can be taken by the electron spin quantum number, ms?
A. ±1/2 B. 0 C. ±1 D. ±2 E. ±3
Over withdrawal of groundwater causes ground subsidence in areas
A) of karst topography.
B) underlain by unconsolidated sediments.
C) underlain by consolidated sediments.
D) all of these
What mass would have to be condensed to a radius of 1.0 × 10-15 m (the order of magnitude of the radius of an atomic nucleus) in order for it to become a black hole? G = 6.67 × 10-11 Nm2/kg2
A) 1.1 × 10-6 kg B) 4.1 × 10-8 kg C) 2.2 × 103 kg D) 6.7 × 1011 kg E) 8.3 × 1015 kg
Which of the following explains why electrons must arrange themselves in atoms with no more than two per energy level, thus making chemistry possible?
A) the exclusion principle B) the uncertainty principle C) the law of conservation of energy D) the law of conservation of angular momentum E) the electromagnetic force law