For part (a) the answer is 400 grams for part (b) 198.63 grams and for part (c) 20 years.
<h3>What is exponential decay?</h3>
During exponential decay, a quantity falls slowly at first before rapidly decreasing. The exponential decay formula is used to calculate population decline and can also be used to calculate half-life.
We have an equation for radioactive decay:

a) Plug t = 0

m(0) = 400 grams
b) plug t = 20 years

After solving:
m(20) = 198.63 grams
c) Plug m(t) = m(0)/2 = 400/2 = 200 grams

x = 19.80 years ≈ 20 years
Thus, for part (a) the answer is 400 grams for part (b) 198.63 grams and for part (c) 20 years.
Learn more about the exponential decay here:
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Answer:
Area of sector = 84.861
Step-by-step explanation:
Given
The radius of the circle = 9
central angle of sector = 
value of pi π = 3.143
To find : the area of sector = ?
We know that the formula to calculate area of sector is given as:
area of sector = (π
Θ)/ 
where, r is radius and Θ is the central angle of the sector
Substituting the known values in above formula, we get
area of sector = (3.143 x
x
) / 
= 84.861
Hence area of sector is 84.861
Answer:
Empirical formula= COOH
Step-by-step explanation:
Molecular mass of the elements
Carbon= 12
Oxygen= 16
Hydrogen= 1
We divide the elements each with their molecular formula
Carbon= 2.4/12
Carbon= 0.2
Oxygen= 6.4/16
Oxygen= 0.4
Hydrogen= 0.2/1
Hydrogen= 0.2
Now we divide with the smallest result which is 0.2
Carbon= 0.2/0.2
Carbon = 1
Oxygen= 0.4/0.2
Oxygen= 2
Hydrogen= 0.2/0.2
Hydrogen= 1
So we have
Carbon 1, oxygen 2, hydrogen 1
Empirical formula= COOH
<span>Step 1: 0.06 = 6⁄100</span>
<span>Step 2: Simplify 6⁄100 = 3⁄50</span><span>
hope this helps:)
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