Answer:
A. 28 years
Explanation:
Applying,
R = R'(2ᵃ/ⁿ).............. Equation 1
Where R = Original sample, R' = Sample left after decay, a = Total time taken to decay, n = half life.
From the question,
Given: R = 12 g, R' = 6 g, a = 28 years.
Substitute into equation 1 and solve for n
12 = 6(2²⁸/ⁿ)
12/6 = 2²⁸/ⁿ
2²⁸/ⁿ = 2
Equation the base,
28/n = 1
n = 28 years.
Hence the half-life is 28 years
"outside visible spectrum" would be the right way to define the power of the goggles provided to the soldiers to see at night. The correct option among all the options that are given in the question is the first option or option "A". I hope the answer comes to your great help.
As you climb it decreases
Additional information
Relative atomic mass(Ar) : A=7, G=16
The empirical formula : A₂G
<h3>Further explanation</h3>
Given
3.5g of element A
4.0g of element G
Required
the empirical formula for this compound
Solution
The empirical formula is the smallest comparison of atoms of compound forming elements.
The empirical formula also shows the simplest mole ratio of the constituent elements of the compound
mol of element A :

mol of element G :

mol ratio A : G = 0.5 : 0.25 = 2 : 1
Answer:
░░░░░▐▀█▀▌░░░░▀█▄░░░
░░░░░▐█▄█▌░░░░░░▀█▄░░
░░░░░░▀▄▀░░░▄▄▄▄▄▀▀░░
░░░░▄▄▄██▀▀▀▀░░░░░░░
░░░█▀▄▄▄█░▀▀░░
░░░▌░▄▄▄▐▌▀▀▀░░ This is Bob
▄░▐░░░▄▄░█░▀▀ ░░
▀█▌░░░▄░▀█▀░▀ ░░ Copy And Paste Him onto all of ur brainly answers
░░░░░░░▄▄▐▌▄▄░░░ So, He Can Take
░░░░░░░▀███▀█░▄░░ Over brainly
░░░░░░▐▌▀▄▀▄▀▐▄░░
░░░░░░▐▀░░░░░░▐▌░░
░░░░░░█░░░░░░░░█
Explanation: