9. How long will it take 120 grams of Strontium-90 to decay to 7.5 grams?
with steps pls

116 years

Explanation:

To solve this, we will use the half life equation;

A(t) = A_o(½)^(t/t_½)

Where;

A(t) is the amount of strontium left after t years;

A_o is the initial quantity of strontium that will undergo decay;

t_½ is the half-life of strontium

t is the time it will take to decay

We are given;

A(t) = 7.5 g

A_o = 120 g

From online values, half life of strontium-90 is 29 years. Thus, t_½ = 29

Thus;

7.5 = 120 × ½^(t/29)

Divide both sides by 120 to get;

7.5/120 = ½^(t/29)

0.0625 = ½^(t/29)

In 0.0625 = (t/29) In ½

-2.772589 = (t/29) × (-0.693147)

(t/29) = -2.772589/(-0.693147)

t/29 = 4

t = 29 × 4

t = 116 years

these nuts

the positions which points up in upward carbon and down in downward carbon are axial

and vice versa holds true for equatorial positions

so the correct answer with labelled diagram will be