The
mass of an atom comes from the protons and neutrons that are found in the
nucleus. The number of protons is the atomic number of an element. To find the
number of neutrons, subtract the atomic number from the mass of an atom. The number of atoms of an
individual element be determined by using a chemical formula and adding all of
the subscripts together after the reaction is complete. The key in the balancing of chemical reaction is to make sure that you got the
exact chemical formula of the substance that is reacting and the yielded
product. After getting the formula, identify first the hardest element/atom to
be balanced such as Na, Zn, Cl, C, O, etc. Then proceed to the easier ones such
as O, H. Make sure to note the atoms present in the molecule of the substance.
The atom is krypton and its symbol is Kr.
the mass number is 41 + 36 = 77
its charge is 0 as it is a noble gas.
Answer:
3.125 grams.
Explanation:
- It is known that the decay of a radioactive isotope isotope obeys first order kinetics.
- Half-life time is the time needed for the reactants to be in its half concentration.
- If reactant has initial concentration [A₀], after half-life time its concentration will be ([A₀]/2).
- Also, it is clear that in first order decay the half-life time is independent of the initial concentration.
∵ Thulium-167 has a half life of 9.0 days.
∴ The time is needed to calculate the grams are left after (36.0 days) represents (36.0 days / 9.0 days) = 4.0 half-lives.
50.0 grams → (first half life) 25.0 grams → (second half life) 12.5 grams → (third half life) 6.25 grams → (fourth half life) 3.125 grams.
So, the grams are left after 36.0 days = 3.125 grams.
Answer:
the answers are either a or d
Explanation:
4 degrees Celsius I think