When the nuclear half-life of the radioactive isotope is showing the time needed for the isotope to be half of its initial value of mass.
so with each half-life, the isotope will be halved of its initial value as example:
after the first half-life, the isotope will lose 50 % of its initial value
and after the second half-life, the isotope will lose 25% of its initial value
and after the third half-life, the isotope will lose 12.5 % of its initial value
and so on,
So here to get how many numbers of half-lives we will use this formula:
numbers of half-lives = total time passed / the half-life of the isotope
= 30 days / 14 days
=2 days
∴remainig mass = initial mass / 2^numbers of half-lives
= 10 g / 2^2
= 2.5 g
Answer:
203 grams
Explanation:
The no. of moles of (6.3 x 10²⁴ molecules--Avagadros number) of NH₃ = (1.0 mol)(7.2 x 10²⁴ molecules)/(6.022 x 10²³ molecules) = 11.96 mol.
The no. of grams of NH₃ present = no. of moles x molar mass = (11.96 mol)(17.0 g/mol) = 203.3 g ≅ 203.0 g.
Some colours appear as white
Answer: I believe this is the answer: The vertical columns on the periodic table are called groups or families because of their similar chemical behavior. All the members of a family of elements have the same number of valence electrons and similar chemical properties. The horizontal rows on the periodic table are called periods.
Good luck on assignment! :)
