Answer:- 9.4 minutes.
Solution:- Radioactive decay obeys first order reaction kinetics and the equation used to solve this type of problems is:
where, k is decay constant and t is the time. 
is the initial amount of the radioactive substance and N is the remaining amount.
Since the value of decay constant is not given, so we need to calculate it first from given half life by using the formula:
where 
stands for half life.
Given half life is 3.0 minutes.
So, 
Let's plug in the values in the first order reaction equation and solve it for t.
It could also be written as:
k = 9.4 min
So, the radioactive substance would take 9.4 minutes to decay from 40.0 grams to 4.5 grams.
Answer:
Stratosphere
Explanation:
Small storms would be residing in the troposphere but stronger thunderstorms and hurricanes reside in the stratosphere.
3AgNO₃ + Na₃PO₄ → Ag₃PO₄ + 3NaNO₃
Explanation:
AgNO₃+Na₃(PO₄) → Ag₃(PO₄) + NaNO₃
To balance this chemical equation, we can adopt a simple mathematical approach through which we can establish simple and solvable algebraic equations.
aAgNO₃ + bNa₃PO₄ → cAg₃PO₄ + dNaNO₃
a, b, c and d are the coefficients needed to balance the equation.
Conserving Ag: a = 3c
N: a = d
O: 2a + 4b = 4c + 2d
Na: 3b = d
P: b = c
let a = 1; d = 1
b = 
c =
Multiplying through by 3:
a = 3, b = 1, c = 1 and d = 3
3AgNO₃ + Na₃PO₄ → Ag₃PO₄ + 3NaNO₃
Learn more:
Balanced equation
brainly.com/question/5964324
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KOH + H2SO4 —> K(+) + HSO4(-) + H2O
Or a total reaction
2 KOH + H2SO4 —> 2 K(+) + SO4(2-) + 2 H2O
