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snow_lady [41]
4 years ago
13

Which chemical reaction absorbs energy?

Chemistry
1 answer:
marissa [1.9K]4 years ago
4 0

I think it is 5) activated hand warmers. :D

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If a neutral atom of oxygen has 8 protons, 8 electrons, and 7 neutrons, what number is the mass number of this atom?
irakobra [83]
Mass number = number of protons + number of neutrons

mass number= 8 + 7= 15 ---> the answer is B. 
4 0
4 years ago
Which of the following best describes a safety precaution needed in nuclear power plants? (1 point)
kap26 [50]
Nuclear power plants produce energy in terms of electricity from radioactive materials. These elements are highly unstable due to their high neutron-to-proton ratio. That's why they spontaneously decay by giving off sub-atomic particles which yields a new element. So, nuclear reactions, fission and fusion, produce 'clean' energy because they do not produce gaseous by-products that could harm the environment. They only yield radioactive materials that could be harmful to the health of people nearby the area. Because of this risk, safety precautions are needed in a nuclear power plant.

Smokestacks are no longer used in nuclear power plants because there are no gases. So, the first choice is eliminated. Next, you should NOT ventilate the radioactive materials. Remember this radiation travels through all types of matter so it is harmful. These type of materials are strictly contained and handled. The third choice is correct because it prevents radiation to reach the outside environment. The last option, on the other hand, is not justifiable. Before a nuclear power plant is approved by the government, it is made sure that all its employees and employers are inherently safe. Otherwise, it would not be put into operation.

Therefore, the answer is letter C.
7 0
3 years ago
When 55.8 g of Fe reacts with Cl2 according to the equation 2Fe + 3Cl2 --> 2FeCl3. How many moles of Cl2 are required to reac
harkovskaia [24]

Answer:

1.50 moles

Balanced equation:  2Fe + 3Cl₂ --> 2FeCl₃

<u>find moles of iron:</u>

moles = mass/Mr

moles = 55.8/56

moles = 0.9964 moles

<u>use molar ratio:</u>

2Fe : 3Cl₂

2 : 3

moles of Cl₂ = (0.9964/2)*3 = 1.50 moles

8 0
3 years ago
Jenny knows that the atomic number of the element potassium, K, is 19. She also
hoa [83]

Answer:

c. 39

Explanation:

You round the number 39.098 to make it easier. Since you can't round it up to forty because the number after the 9 in-front of the decimal is a over i is unable to be rounded up

8 0
4 years ago
Read 2 more answers
If 1.85 g Al reacts with an excess copper(II) sulphate and the percentage yield of Cu is 56.6%, what mass of Cu is produced
timofeeve [1]
We have a balanced equation: 
2 Al+ 3 CuSO4 ⇒ Al2(SO4)3+ 3 Cu

1.85 g Al* (1 mol Al/ 26.98 g Al)* (3 mol Cu/ 2 mol Al)* ( 63.55 g Cu/ 1 mol Cu)= 6.54 g Cu.
(Note that the units cancel out so you get the answer)

6.54 g Cu* (56.6/100)= 3.70 g Cu.

The final answer is 3.70 g Cu~
7 0
4 years ago
Read 2 more answers
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