The half life for C14 is 5730 years.
We assume that Carbon 14/ Carbon 12 ratio was steady for living organisms over time, the problem is actually telling us that

= 0.0725 =

ˣ
Take the natural logarithm and In on both sides.
ln(0.725) = ln

ˣ
= - 0.3216 = xln (

= -0.6931x.
So x = (-.3216) / (-0.6931) = 0.464
or
t/t₁/₂ = 0.464
So t = 0.464 x t₁/₂ = 0.464 * 5730 yrs = 2660 years.
Answer is: lithium is the least reactive and potassium is the most reactive of the three alkali elements.
<span>The </span>reactivity<span> of the alkali metals increases down the group because one valence electron (I group of Periodic system of elements) is farther away from nucleus and attraction force between electron and proton is weaker.</span>
Answer:
0.119 moles
Explanation:
Given that,
Mass measured by Nurse Antonio is 7 grams of NaCl
To find,
The no of moles of NaCl
Solution,
The number of moles is given by

m is given mass
M is molar mass
For NaCl, molar mass is 23+35.5 = 58.5 grams
So,

Therefore, there are 0.119 moles of NaCl.