Number of significant figures. PART I. Vocabulary Review: Use the following phrase Bank to answer questions 1-4.
1. A mole is a unit
defined to be
Phrase Bank
A. the actual Il of atoms present in one molecule
B. mole of the element
c. 6.02 x 10 ? particles of a substance
D. formula unit

For ai it's atomic number is 13 and it's mass number is 27 how many neutrons does it have

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Observation and experimentation have led many scientists to accept a theory about the origin of the universe. this theory is called the big bang theory. scientific evidence collected and observed by scientists around the world suggests that the universe is ever expanding from a hot and dense initial state. what makes this a scientific theory? (2 points)