12. F - Most of these elements are metals.
13. C - Ability to rust
The answer is B photosynthesis
Strontium element has a mass number of 88 and contains 50 neutrons in the atom.
Given that;
Mass number of element X = 88
Number of Neutrons in element X = 50
we know the concept that Mass number is represent as total number of Neutrons and proton present in Nucleus
So, Mass number of element X = Number of Neutrons in element X + Number of Protons in element X
Thus, 88 = 50 + Number of Protons in element X
Number of Protons in element X = 38
As, Number of proton = Atomic number
So, Atomic number of element X = 38
Hence Unknown Element X is Strontium
To know more about Strontium element visit here ; brainly.com/question/19298437?referrer=searchResults
#SPJ4
Answer:
5 mg
Explanation:
If one half life is 4 hours, then 3 half lives is 12 hours.
This means that the sample will decay to 1/8 of its original amount.
So, the answer is 40(1/8) = 5 mg.
