Answer:
118 elements
Explanation:
Of these 118 elements, 94 occur naturally on Earth.
The answer is A, Lithium and Sodium.
Higher, they have more energy so they move faster
B) The carbon atoms in graphite are arranged in widely spaced layers
Explanation:
Graphite is different from other allotropes of carbon because the carbon atoms in graphite are arranged in widely spaced layers. Graphite and diamond are the two main allotropes of carbon that are closely related.
- Both allotropes forms under extreme temperature and pressure. In geology, they are categorized as derivatives of changed rocks.
- Graphite is different from carbon because its atoms are arranged in widely spaced layers.
- Diamond has a packed and cross-linked structure that makes it rigid and very hard.
Learn more:
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Answer:
12.213 minutes will be taken for 120 g-Thalium-208 to decay to 75 grams.
Explanation:
Radioactive isotopes decay exponentially in time, the mass of the isotope (
), in grams, is described by the formula in time (
), in minutes:
(1)
Where:
- Initial mass of the isotope, in grams.
- Time constant, in minutes.
In addition, the time constant associated with the isotope decay can be described in terms of half-life (
), in minutes:
(2)
If we know that 
, 
and 
, then the time taken by the isotope is:
12.213 minutes will be taken for 120 g-Thalium-208 to decay to 75 grams.
