Answer: According to the reactivity of metals Sodium is the second metal while Magneesium is the fourth metal. The metal in the top of the reactivity serise table are more reactive.
<em>(The series obtained by the arrangement of metals in the decending oder of their reactivity is the REACTIVITY SERIES TABLE)</em>
Explanation:
K
<u><em>Na</em></u>
Ca
<u><em>Mg</em></u>
Al
Zn
Fe
Sn
Pb
H
Cu
Hg
Ag
Pt
Au
Therefore Sodium is more reactive than Magnesium
After 160 years, the activity level of the sample will be 0.5 curies.
<h3>What is half-life?</h3>
Half life of any radioactive waste is the half decay of that product.
The formula is 
Where, λ is 4 cruies
λ1 is 0.5 cruies
b = 40 years
Putting the values in the equation

Thus, the correct option is 160 years.
Learn more about half-life
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To prepare 350 mL of 0.100 M solution from a 1.50 M
solution, we simply have to use the formula:
M1 V1 = M2 V2
So from the formula, we will know how much volume of the
1.50 M we actually need.
1.50 M * V1 = 0.100 M * 350 mL
V1 = 23.33 mL
So we need 23.33 mL of the 1.50 M solution. We dilute it
with water to a volume of 350 mL. So water needed is:
350 mL – 23.33 mL = 326.67 mL water
Steps:
1. Take 23.33 mL of 1.50 M solution
<span>2. Add 326.67 mL of water to make 350 mL of 0.100 M
solution</span>
A, The moon pulls on the earth making the tides rise and fall