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ale4655 [162]
3 years ago
14

If the half-life of a radioisotope is 20,000 years, then a sample in which three-quarters of that radioisotope has decayed is __

_________ years old
Chemistry
1 answer:
poizon [28]3 years ago
4 0
25% remaining = 40,000 years old
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A researcher wants to determine if a unicellular organism he discovered is an autotroph or a heterotroph. He radioactively label
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Answer:

A

Explanation:

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Which compound has the same empirical and molecular formula ethyne ethene ethane methane?
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Empirical formula is the simplest ratio of whole numbers of components in a compound 
molecular formula is the actual ratio of components in a compound .
the molecular formula for the compounds given are as follows
ethyne  - C₂H₂
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ethane - C₂H₆
methane - CH₄
the actual ratios of the elements                 simplified ratio
                     C : H                                           C : H
ethyne            2:2                                             1:1
ethene            2:4                                             1:2
ethane            2:6                                             1:3
methane         1:4                                             1:4
the only compound where the actual ratio is equal to the simplified ratio is methane 
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Evgesh-ka [11]

The element with 8 electrons in its 3d sublevel is Ni, Nickel. The answer is letter D. The rest of the choices do not answer the question above. 

5 0
3 years ago
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The ____ can be described as the basic unit of life. (2 points) atom neutron cell nucleus
Verizon [17]

Answer:

the cell can be the described as the basic unit of life

8 0
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