Here are the answers to your questions:
Question 15
To determine how much of element B is needed when 48g of A is used, we first need to calculate the number of moles of A present in the reaction.
\[ \text{Moles of A} = \frac{\text{mass of A}}{\text{molar mass of A}} = \frac{48g}{4g/mol} = 12 \text{ moles of A} \]
From the balanced equation \(3A_2 + 2B \rightarrow 2A_3B\), we can see that 3 moles of \(A_2\) react with 2 moles of \(B\). Therefore, 12 moles of A will react with the following number of moles of B:
\[ \text{Moles of B} = \frac{2}{3} \times 12 = 8 \text{ moles of B} \]
Now, we can find the mass of B:
\[ \text{Mass of B} = \text{moles of B} \times \text{molar mass of B} = 8 \text{ moles} \times 16g/mol = 128g \]
Answer: 128g
Question 16
To calculate how many molecules of \(CO_2\) are in a 17-gram sample, we first need to determine the molar mass of \(CO_2\):
\[ \text{Molar mass of CO}_2 = (1 \times 12.01 , \text{g/mol}) + (2 \times 16.00 , \text{g/mol}) = 12.01 + 32.00 = 44.01 , \text{g/mol} \]
Next, we can find the number of moles in the sample:
\[ \text{Moles of CO}_2 = \frac{17g}{44.01g/mol} \approx 0.386 , \text{moles} \]
Using Avogadro's number (approximately \(6.022 \times 10^{23}\) molecules/mol), we can find the number of molecules:
\[ \text{Number of molecules} = \text{moles} \times \text{Avogadro's number} = 0.386 \times 6.022 \times 10^{23} \approx 2.32 \times 10^{23} \]
Answer: 2.326×10²³
Question 17
Nuclear reactions generally conserve the total number of protons and neutrons, meaning that while individual numbers can change during the reaction (protons can change into neutrons and vice versa), the total number remains constant.
Answer: The relative numbers of protons and neutrons can differ before and after the change, but the total number of those particles remains the same.
Question 18
Fission is the process whereby a large atomic nucleus, typically of uranium or plutonium, is split into two or more smaller nuclei, along with a release of energy.
Answer: Fission is a process in which a large nucleus is split into smaller nuclei.
Question 19
When a nucleus decays and results in a nucleus with one additional proton, it typically indicates that a neutron has transformed into a proton, which is characteristic of beta-plus decay.
Answer: beta-plus decay
Question 20
Nuclear fission is involved in the process of splitting a large nucleus into smaller parts. Since alpha and beta decays do not involve splitting a nucleus into smaller nuclei, they do not represent forms of fission.
Answer: None of the options you provided (alpha decay, gamma decay, or beta decay) are forms of nuclear fission on their own. However, the process of fission itself is distinct from these decay processes.
Question 21
A nuclear power plant generates electrical energy from the heat produced in nuclear fission reactions.
Answer: electrical energy
Question 22
- A chain reaction occurs: True
- Uranium atoms are split: True
- Light nuclei come together to form a single heavier nucleus: False
- A large nucleus is split into smaller nuclei: True
This means for the fourth option, it's false that light nuclei come together because that describes fusion, not fission.
Feel free to ask more questions if needed!