Answer:
Explanation:
A radioactive isotope is an isotope that undergoes nuclear decay, breaking apart into a smaller nucleus and emitting radiation during the process.
The half-life of an isotope is the amount of time it takes for a certain quantity of a radioactive isotope to halve.
For a radioactive isotope, the amount of substance left after a certain time t is:
(1)
where
is the mass of the substance at time t = 0
m(t) is the mass of the substance at time t
is the half-life of the isotope
In this problem, the isotope is uranium-235, which has a half-life of
We also know that the amount of uranium left in the rock sample is 6.25% of its original value, this means that
Substituting into (1) and solving for t, we can find how much time has passed:
Answer:
Empirical formulas can be determined from the percent composition of a compound. In order to determine its molecular formula, it is necessary to know the molar mass of the compound. Chemists use an instrument called a mass spectrometer to determine the molar mass of compounds.
<span>All acids form their conjugate base and a proton or H+ in an aqueous solution, in water. Since formic acid is an acid, although a weak electrolyte, it will react with water to form the conjugate base HCOO with a negative 1 charge. The other solute will be the proton H+, also written as hydronium H3O+.</span>
A nuclear reaction changes the number of protons and or neutrons in an atom.
<h3>What do nuclear reactions change in the atom?</h3>
A nuclear reaction is a type of reaction that results in the change of the nucleus of an atom. We know that a nucleus of an atom is made up of protons and neutrons.
So we can conclude that a nuclear reaction changes the number of protons and or neutrons in an atom.
Learn more about reaction here: brainly.com/question/26018275
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Answer: it reacts with the alkali metals (M) to form a salt MX, where X is the halogen.
Explanation: Group 7A elements are halogen and they react with alkali metals like Sodium or potassium to form a salt like NaCl
