Science
CHECK MY ANSWERS!!!!!!!
1) Cobalt has a mass number of 59 and an atomic number of 27. A student wants to create a model of a cobalt atom. Which statement about the model is correct?(1 point)
A. The model should show 27 protons and 32 neutrons.******
B. The model should show 59 protons and 27 neutrons.
C. The model should show 27 protons and 27 neutrons.
D. The model should show 32 protons and 59 neutrons.
2) In a molecule of lithium sulfide, there are two atoms of lithium and one atom of sulfur. Which statement about lithium sulfide is correct?(1 point)
A) The chemical formula for lithium sulfide is LiS2.
B) The atoms in lithium sulfide are held together by bonds.*****
C) Both lithium and sulfur form positive ions.
D) A molecular model of lithium sulfide would have two spheres.
3)Which element has the same number of valence electrons as bromine (Br)? (1 point)
A) ytterbium (Yb)
B) selenium (Se)
C) krypton (Kr)******
D) astatine (At)
4) Why are sodium (Na) and potassium (K) in the same group on the periodic table?(1 point)
A) They have similar reactivity.*******
B) They are both hard and brittle.
C) They have similar atomic weights.
D) They are both colorless.
5) A student cuts some fabric into two pieces. Is this change physical or chemical?(1 point)
A) It is a chemical change because there is no phase change.
B) It is a chemical change because the size changes.
C) It is a physical change because the process is reversible.
D) It is a physical change because there is no reaction.******
6) How are chemical changes different from physical changes?(1 point)
A) They form new substances.********
B) They are reversible.
C) They involve heat.
D) They include shifts in the phase of matter.
7)A scientist makes several observations about a chemical reaction and records them in the table shown. Which observation contains an error? (1 point) picture added!
A) 1
B) 3
C) 2******
D) 4
8) In a chemical reaction, hydrofluoric acid (HF) and sodium hydroxide (NaOH) combine to form sodium fluoride (NaF) and water (H2O). The reaction uses 20 grams of hydrofluoric acid and 40 grams of sodium hydroxide, and it produces 18 grams of water. How much sodium fluoride does the reaction produce?(1 point)
A) 60 grams
B) 42 grams
C) 18 grams******
D) 78 grams
9)Which procedure could be used to demonstrate that matter is conserved during a physical change?(1 point)
A) Find the mass of an apple. Cut the apple and remove the core. Find the mass of the remaining apple.
B) Find the mass of a raw egg. Cook the egg. Find the mass of the cooked egg.********
C) Find the mass of a cup of water. Boil the water. Find the mass of the water that remains.
D) Find the mass of a piece of ice. Let the ice melt. Find the mass of the liquid water.
10) One molecule of bromine (Br2) and two molecules of potassium chloride (KCl) combine in a reaction. How many atoms are in the products?(1 point)
A) two******
B) four
C) three
D) six
11) Use the unbalanced chemical equation to answer the question.
2NaHCO3 → Na2CO3 + CO2
What can be added to the products to balance the equation? (1 point)
A) CH2OH****
B) H2O
C) H2
D) O2
12) The chemical formula for phosphorus trichloride is PCl3. In one to two sentences, explain how you would build a ball-and-stick model of phosphorus trichloride. Include a description of the parts of the model.(2 points)
13) Copper (Cu) reacts with sulfur (S) to form copper sulfide as shown in the chemical equation. A scientist adds 4 grams of Cu to 2 grams of S to start the reaction. At the end of the experiment, she has 6 grams of product. In one to two sentences, explain what would happen if the scientist increased the amount of copper to 6 grams, and why. (1 point)
☆Alexa☆
yesterday at 6:29pm
answers: (NOT IN ORDER!!!)
- It is a physical change because there is no reaction.
- They form new substances.
- it shows that no atoms have been gained or lost during the reaction
- Synthesis and decomposition reactions are opposites of each other. Synthesis reactions are in the form A + B → AB, while decomposition reactions are in the form AB → A + B.
- 4:3
- single displacement
- a substance that gains an electron in a reaction
- oxygen
- There is an extra O2 molecule left over.
- six
- H2O
- double replacement
@nebula
ITS BEEN SIX DAYS PLEASE BRO
WHAT ARE THE AWNSERS
1 and 2 are OK. 3 is wrong. Kr is a noble gas and is not in the column with the halogens (F, Cl, Br, I). Look on the periodic table and find the element listed in the choices there to see which is in the halogen column. 4 is OK. 5 and 6 are OK. 7 there is no picture. 8 is wrong. You have 60 g reactants so you must have 60 g products. The problems tells you H2O is 18 of that so 60-18 = ? must be the other one. 9 I think is correct IF you leave the egg in the shell (meaning to boil it) but think D is a better answer and probably the one expected by the author of the problem. 10 is correct BUT note that no reaction takes place so you have the atoms of Br2 present before and after. 11 is wrong. I see the Na is balanced, the C is balanced which leaves just H and O that are not balanced. For the answer choices I see only one that has both H and O so I would use that. 12. I answered this for another student but I don't have that link. If you will go to Google and type in something like ball and stick model for PCl3 you should find some good pictures. 13 leaves me perplexed. I don't think there is a good answer because I had trouble finding what the problem was all about. I THINK, but I don't know, the author meant for this problem to be a teaching point in which Cu would be the limiting reagent in one part and S would be the limiting reagent in the other part. That's not the way it works out so the only conclusion I could draw was that using more Cu produced more Cu2S. But that's an obvious conclusion anyway. Personally, I think the author of the problem made a miscalculation and stated the problem in a way that wasn't intended.
Hope this helps. Good luck.
hi
Write a 5 paragraph essay explaining why communal showers are common in America?
y'all what the.... okay whatever ill give yall answers soon i guess-nebula the real one
As an AI language model, I do not have personal beliefs or opinions, but I can provide you with some reasoning as to why communal showers are common in America.
Firstly, communal showers are found in facilities where large numbers of people congregate in one place, such as residential universities, military barracks, or prisons. The main reason this happens is that including separate toilets and showers from each living unit would lead to a more expensive project.
Secondly, communal showers may promote socialization among individuals sharing the same facility. Shared experiences can bring people together, and the presence of communal showers can provide an area for and encourage conversation and interaction between people.
On the other hand, it can also be argued that communal showers are permitted due to the cultural norms in the United States, which tend to socialize people more openly. This is different from other countries, like in Europe, where people are accustomed to more private accommodations.
At the same time, people in communal showers are undressed and a lack of privacy may cause individuals discomfort, anxiety and feelings of shame or vulnerability. This has led to requests for greater individual privacy, which is why many newly built facilities, or refurbished older ones, combine communal facilities with private showers as well.
In conclusion, there may be a variety of reasons why communal showers are still common in America, including cost-saving measures, socialization benefits, or cultural norms. However, there may also be challenges such as privacy concerns, and many newer facilities have opted to include private showers as well.