The percentage abundance is a measure of ratio of the number of each isotope and the total number of the element. The percentage abundance of each isotope is :
- Le - 19 = 0.32
- Le - 17 = 0.44
- Le - 15 = 0.24
Number of each isotope in the sample :
- Le - 19 = 16
- Le - 17 = 22
- Le - 15 = 12
Total number of sample = 50
The percentage natural abundance of the isotopes can be calculated :
Number of each isotope ÷ total number of sample
Percentage abundance of Le isotopes
- Le - 19 =
- Le - 17 =
- Le - 15 =
Therefore, the percentage abundance of Le - 19, Le - 17 and Le - 15 isotopes are 0.32, 0.44 and 0.24 respectively.
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Answer:
Explanation:
In one Ca(OH)₂ molecule, there are 5 atoms (1 Ca, 2 O and 2 H). This means that in 1.005x10²⁴ Ca(OH)₂ molecules, there are (5 * 1.005x10²⁴) 5.025x10²⁴ atoms.
To <u>convert molecules into moles</u>, we use <em>Avogadro's number</em>:
- 1.005x10²⁴ molecules *
= 1.6686 moles
Finally, we <u>convert moles into grams</u> using the <em>molar mass of Ca(OH)₂</em>:
- 1.6686 moles * 74.093 g/mol = 123.63 g
Answer: A is condensation and B is freezing.
The process in which the gas changes to the liquid phase due to the removal of heat is known as condensation. Rains are formed in this way. The water vapour rises. As it raises above it loses heat and then cools down and condenses and comes down as rainfall.
The process in which the liquid changes to a solid on removal of heat is known as freezing. Formation of ice is an example. When the heat is removed at -4 degree Celsius the water freezes to ice.
