Answer:
Two Half-lives
Explanation:
Let number of Parent nuclei Initially present be X,
Then, finally 
Parent nuclei Will remain with 
daughter nuclei.
In one half- life , parent nuclei becomes half of initial.
So, starting with X parent nuclei,
After one half-life, it will degrade to 
.
After another half life , Parent nuclei will become half of
Which is equal to .
So, Parent nuclei have to go through Two half-lives.
The products will be 
<h3>Chemical reactions</h3>
Zn is higher than hydrogen in the reactivity series. Thus, it will be able to displace hydrogen from the acid.
The equation of the reaction becomes: 
Hydrogen gas is released as a result. In fact, it is one of the ways of preparing hydrogen gas in the laboratory.
More on chemical reactivity can be found here: brainly.com/question/9621716
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Rounded to 1 significant figure, 25 m would go to 30. This is because 0 isn't significant, so the 3 is the only significant figure.
Answer is: mass number is 234.
Beta decay is radioactive decay<span> in which a </span>beta ray<span> and a </span>neutrino<span> are emitted from an </span><span>atomic nucleus.
</span>There are two types of beta decay: beta minus<span> and </span>beta plus. <span> In beta minus </span><span>decay, neutron is converted to a proton and an </span>electron<span> and an </span>electron antineutrino and in beta plus <span>decay, a proton is converted to a neutron and </span>positron<span> and an </span>electron neutrino, so mass number does not change.
Bismuth = Bi
cesium = Cs
bismuth + cesium = BiCs
