they are correct, because i had gotten it correct on my test but they are also correct because what they have shown for proof is correct. I had to do research about this in the past, everything they say is 100% correct, and trustworthy.
Hence, the correct answer is nicotine.
Answer:
The half life of the radioisotope is 12 hours.
Explanation:
Initial mass of the radioisotope = x
Final mass of the radioisotope = = 0.0625x
Half life of the radioisotope =
Age of the radioisotope = t = 48 hours
Formula used :
where,
= initial mass of isotope
N = mass of the parent isotope left after the time, (t)
= half life of the isotope
= rate constant
Now put all the given values in this formula, we get
The half life of the radioisotope is 12 hours.
protons
neutrons
gamma rays
Answer: Option (a) is the correct answer.
Explanation:
A chemical reaction is the reaction that involves gain and loss of electrons due to which there is formation of new compounds or products.
Foe example,
That is, in chemical reactions change in oxidation state of reactants occur.
Hence, we can conclude that out of the given options electrons participates in chemical reactions.
Answer:
10.7 g of KOH
Explanation:
First of all, we determine the reaction:
2K (s) + 2H₂O(l) → H₂(g) + 2KOH(aq)
We convert the mass of K, to moles → 7.5 g . mol/39.1 g = 0.192 moles
Ratio is 2:2, so the moles I have of K must produce the same moles of KOH. In this case, the produces moles of KOH are 0.192 moles.
We convert the moles to mass, to finish the answer:
0.192 mol . 56.1g /1mol = 10.7 g of KOH
chemical precipitation of a solid
production of a gas
change in volume
Answer: Option (d) is the correct answer.
Explanation:
A change that does not cause any difference in chemical composition of a substance are known as physical change.
For example, shape, size, mass, volume, density, etc of a substance are all physical changes.
And, a change that causes changes in chemical composition of a substance is known as chemical change.
For example, precipitation, reactivity, toxicity etc are chemical change.
Therefore, change in temperature, chemical precipitation of a solid, production of a gas are all indications of a chemical change.
Thus, we can conclude that change in volume would not necessarily indicate a chemical reaction.
Of the options provided, a change in volume would not necessarily indicate a chemical reaction. It could also be a sign of a physical change, such as a change in state.
The question is asking which of the listed factors would not necessarily indicate that a chemical reaction has taken place. From the options provided, a change in volume is not necessarily indicative of a chemical reaction. Other signs (like change in temperature, chemical precipitation of a solid, or production of a gas) are often valid signs of a chemical reaction, however, just a volume change could also be a sign of a physical change, such as a change in state from solid to liquid, or liquid to gas.
For example, when ice melts to water, or water evaporates to steam, it experiences a change in volume. This does not involve the forming or breaking of chemical bonds, thus it's not a chemical reaction, but a physical change.
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