Im not sure but i think its hbr. i hope im right and i hope this helped,
Answer: The pure metal has low structural strength, magnesium is mainly used in the form of alloys- principally with 10% or less of aluminum, zinc, and manganese- to improve it's hardness, tensile strength, and ability to be cast, welded, and machined.
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4. the nervous system uses electrical impulses to send messages through neurons while endocrine glands use hormones to send messages
5. Hormones are released from the endocrine glands
6. a. neck
b. Chest
7. help regulate important functions, such as growth, blood pressure and reproduction; it is small and small and bean shaped.
8. produces hormones that regulate the body's metabolic rate controlling heart, muscle and digestive function, brain development.
9. regulate your metabolism, immune system, blood pressure, respond to stress etc.
10. “enzymes” - break down sugars, fats, and starches
11. cells are unable to use glucose (can’t break down sugar to use as energy)
Answer:
Therefore it will take 7.66 hours for 80% of the lead decay.
Explanation:
The differential equation for decay is
Integrating both sides
ln A= kt+c₁
[
]
The initial condition is A(0)= A₀,
.........(1)
Given that the 
has half life of 3.3 hours.
For half life 
putting this in equation (1)
[taking ln both sides, 
]
⇒k= - 0.21
Now A₀= 1 gram, 80%=0.8
and A= (1-0.8)A₀ = (0.2×1) gram = 0.2 gram
Now putting the value of k,A and A₀in the equation (1)
⇒ t≈7.66
Therefore it will take 7.66 hours for 80% of the lead decay.
