Asample of strontium-90 is found to have decayed to one-fourth of its original amount after 58.2 years. what is the half-life of strontium-90?

Half life of Sr-90 is 29.1 years.

Explanation: Half life is the time in which the substance remains halve of its original amount. Let's say originally we have 100 grams of Sr-90. From given information, it remains one-fourth of its original amount in 58.2 years.

One-fourth of 100 gram will be 25 gram. The equation used for solving this type of problems is:

where, n is the number of half lives, is the original amount of the radioactive substance and N is the remaining amount.

From above information:

= 100

N = 25

Let's plug in these values in the equation and find out the value of n.

n = 2

From above calculations, the value of n is 2 means there are two half lives.

From the given time and the value of n, we can calculate the half life of the substance using the equation:

half life =

(Where T stands for time)

Let's plug in the values in the equation:

half life =

half life = 29.1 years

So, half life of Sr-90 is 29.1 years.

alkaline metals are lithium, sodium, rubidium, potassium, cesium and francium.

alkali metals have electronegativity from 0.7 to 1, lowest in periodic table of elements, which means that alkali metals (i group in periodic table) has positive oxidation number in compounds.

electronegativity is a chemical property that describes the tendency of an atom to attract a shared pair of electrons towards itself.

alkaline metals (far left in main group) have lowest ionizations energy and easy remove valence electrons,

for example, potassium is the alkali metal and has a single valence electron in the outer electron shell.

electron configuration of potassium is: ₁₉k 1s²2s²2p⁶3s²3p⁶4s¹.

they can not exist alone in nature, because they are very reactive.