How long ago did multicellular life forms appear in the fossil record?
A) 4.5 billion years ago
B) 3.8 billion years ago
C) one billion years ago
D) 63 million years ago
E) 30 million years ago
C
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The Murchison meteorite, a carbonaceous chondrite, contained many of the amino acids needed by living things on Earth
Indicate whether the statement is true or false
Carnot Engine: Two ideal Carnot heat engines have the same efficiency. One operates between 5.0 × 102 K and 3.0 × 102 K, and the other between 4.0 × 102 K and some lower temperature. What is the lower temperature?
A. 200 K B. 220 K C. 240 K D. 260 K E. 280 K
Astronomers generally can measure a star's mass if only it is a member of a binary star system. What characteristics of the stars must we know to measure the masses of the stars in a binary system?
A) their spectral types and their distance from Earth B) their absolute magnitudes and their luminosities C) their orbital period and average orbital distance D) their luminosities and distance from Earth
After nitrogen and oxygen, the major constituent of the air is______________
Fill in the blank(s) with correct word