1. earthquake measures
2. b
3. seismograph
The mass of the star actually determines the stage of the
star after supernova. If the mass of the star is small, then it would become a
very small and dwarf, cold and dead body in space. The mass of the star has to
be less than that of the sun. If the mass of the star is greater than sun, then
it would become a black hole. The mass of the star has to be more than 1.4
times the mass of the sun to become a black hole.
Explanation:
Before a chemical reaction, the elements and compounds which are about to take part in the reaction are known as reactants.
And, when the chemical reaction takes place between the given elements and compounds then they change into products.
For example, we take sodium and chlorine elements and before any chemical reaction they are the reactants.
But when a chemical reaction takes place between sodium and chlorine then it results into the formation of sodium chloride which is the product.
Oxygen-16 and Carbon-12 are stableisotopes of elements O and C respectively. Hence, they do not have half-lives. But Carbon-14 andUranium-238 are radioactive isotopes. Among them Carbon-14 has relatively short half-life as about 5730 years while Uranium-238 has a long half-life as about 4.5 billion years.
Answer is. uranium-238
