Which of the following describes the element Kr? Choose all that apply. (A) belongs to a group consisting entirely of gases form
1 answer:
Answer:
The correct answer is option C.
Explanation:
Kr is the symbol of a noble gas named krypton.It belongs to the group 18 of the periodic table in which all the elements are less reactive.
These noble gases are highly inert and less reactive due to:
- Completely filled
electronic configuration in their valence shell.
- High ionization enthalpies.
- Positive value of electron gain enthalpy.
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After 160 years, the activity level of the sample will be 0.5 curies.
<h3>What is half-life?</h3>Half life of any radioactive waste is the half decay of that product.
The formula is
Where, λ is 4 cruies
λ1 is 0.5 cruies
b = 40 years
Putting the values in the equation
Thus, the correct option is 160 years.
Learn more about half-life
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Answer:
Option a: positron emission.
Explanation:
In the transformation we have:
⁶⁷Ga → ⁶⁷Zn
The reaction is:
For Ga to become Zn, the atom nucleus has to lose a proton, so in the given options, the reaction that involves the transformation of a proton is the option a, positron emission.
In a positron emission, a proton becomes into a neutron and a positron:
Therefore, the correct answer is option a: positron emission.
I hope it helps you!