chất có ở đâu ? nước tự nhiên là chất hay hỗn hợp
Answer:
Water, H2O, is a pure substance, a compound made of hydrogen and oxygen. Although water is the most abundant substance on earth, it is rarely found naturally in its pure form. Most of the time, pure water has to be created. Pure water is called distilled water or deionized water.
What is the best definition of
molecule?
A. A molecule is an atom that cannot be broken
down.
B. A molecule is a positively charged partide.
C. A molecule is the smallest part of a substance
that is still that substance
Answer:
C
Explanation:
A molecule is a smallest particle of a substance that has all of the physical and chemical properties of that substance. or
Molecules are two or more atoms chemically joined together.
define mitochondria.
Answer:
An organelle found in large numbers in most cells, in which the biochemical processes of respiration and energy production occur. It has a double membrane, the inner part being folded inwards to form layers (cristae).
Explanation:
Is Cl2 chlorine, dichlorine or dichloride?
Answer:
Cl² is dichlorine
Explanation:
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Describe the formation of a hot spot?
Please help!
Answer:
A volcanic "hotspot" is an area in the mantle from which heat rises as a thermal plume from deep in the Earth. High heat and lower pressure at the base of the lithosphere (tectonic plate) facilitates melting of the rock. This melt, called magma, rises through cracks and erupts to form volcanoes.
out of magnesium and Calcium which element is more reactive give reason
Answer:
Calcium is more reactive.
Explanation:
It is higher in the reactivity series, and contains more energy levels.
An Exothermic reaction is
o when energy is released
O when energy is absorbed
O When energy is not released or absorbed
O No answer text provided.
A 2.00 mL of substance A has a density of 18.4 g/mL and a 5.00mL sample of substance B has a density of 35.5 g/mL. Do you have an equal mass of Substances A and B.
Answer:
No, you have more mass of substance B
Explanation:
use d =m/v to find mass
m= d*v
mass A = 18.5 g/mL * 2.00 mL = 37 g
mass B = 35.5 g/mL * 5.00 mL = 177.5 g
No, the substances A and B does not have equal mass. A further explanation is provided below.
Given:
Density,
D₁ = 18.4 g/mLD₂ = 35.5 g/mLVolume,
V₁ = 2.00 mLV₂ = 5.00 mLAs we know,
→ [tex]Mass = Density\times Volume[/tex]
The mass of substance A will be:
→ [tex]m_A = 2.00 \ mL\times 18.4 \ \frac{g}{mL}[/tex]
[tex]= 2.00\times 18.4 \ g[/tex]
[tex]= 36.8 \ g[/tex]
The mass of substance B will be:
→ [tex]m_B = 5.00 \ mL\times 35.5 \ \frac{g}{mL}[/tex]
[tex]= 5.00\times 35.5 \ g[/tex]
[tex]= 177.5 \ g[/tex]
We can see that [tex]m_A \neq m_B[/tex].
Thus the above response is correct.
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Which is correct?
a
Electrons in a p sublevel can shield the s electrons that are in the same
principal energy level.
b
Electrons in an s sublevel can shield the p electrons that are in the same
principal energy level.
с
Both a and b are true.
d
Neither a nor b are true.
which one is more reactive out of fluorine and chlorine. why?
Answer:
fluorine
Explanation:
because it is at the top of the halogen group, which is the second to right group on the periodic table. With halogens, the higher an element is in the column, the more reactive it is. Halogens are reactive because the outer shells that orbit the nucleus lack electrons.
also because it has low dissociation energy and the valence bonding is seen close to the nucleus hence the attraction for a new electron is greater and can gain an extra electron more easily.-if ur in a higer grade u will understand this
How many moles are there in 4.6g of sodium
Answer:
0.20moles
Explanation:
1 mole Na contains 23 g Na
23 g Na =1 mole of Na
1 g Na= 1/23 moles of Na
4.6 g Na= 1/23×4.6= 4.6/23=0.2 moles
Therefore 0.2 moles are present in 4.6 g of Na
Answer:
the 4.6g sodium has 0.2 moles
Two skaters stand on ice. one weights 250 N, and the other weights 500 N. They push against each other and move in opposite directions. Describe the momentum of each skater after they push away from each other.
Answer:
Because law of momentum, makes it equal
What is the molar mass of C3H8O2? (Round to three significant figures)
Answer:
The molar mass of [tex]C_3H_8O_2[/tex] (rounded to three significant figures) is 76.1 amu.
Step-by-step explanation:
Hey there!
To answer this question, you will need access to a periodic table. You need to know the atomic masses of carbon (C), hydrogen (H), and oxygen (O) in order to answer this question. With that out of the way, let's begin!
We have a chemical formula: [tex]C_3H_8O_2[/tex].
The letters are element symbols, which are basically the code for an element. Think of it as an abbreviation or something similar to an ID.The subscripts (numbers) help us identify how many atoms of each element are included in the substance.The first thing we should do is locate C, H, and O on a periodic table and figure out the atomic masses for each element. This will help us determine the total molar mass of the substance.
Determining the Atomic Mass of CIf we locate C on a periodic table, we see that its atomic mass is roughly 12.01 amu (atomic mass units). Then, we have a subscript of 3, so we simply multiply the subscript by the given atomic mass in order to find the atomic mass of the three atoms of carbon.
[tex]3 \times 12.01 = 36.03 \text{ amu}[/tex]
This means that C accounts for 36.03 amu of the molar mass of the substance.
Determining the Atomic Mass of HUsing the same principle as before, we want to find the atomic mass of one atom of H. This is 1.008, so we will multiply 1.008 by the eight atoms (pay attention to the subscript) in order to find the atomic mass of hydrogen in the substance.
[tex]8 \times 1.008 = 8.064 \text{ amu}[/tex]
This means that H accounts for 8.064 amu of the molar mass of the substance.
* An important note to add is that we should never round our values until the end of the problem so we make sure to get as close as possible (this is why you learn about accuracy and precision in a chemistry class).
Determining the Atomic Mass of OFinally, we want to find the atomic mass of O in the substance, so we'll use the same method as before and locate the atomic mass of one atom of oxygen. We find that this is 15.999, which would definitely round to 16.00, but remember the rules for rounding in chemistry in order to be as accurate as possible. Since our subscript is 2, we know that there are two oxygen atoms, so we will multiply the atomic mass of oxygen by 2.
[tex]2 \times 15.999 = 31.998 \text{ amu}[/tex]
This means that O accounts for 31.998 amu of the molar mass of the substance.
Summation of the Determined Atomic MassesAfter you have determined the atomic masses of the atoms in the chemical substance, you have to add these together. This is performed with simple addition.
C = 36.03 amuH = 8.064 amuO = 31.998 amuNow, let's add these together.
[tex]36.03 \text{ amu} + 8.064 \text{ amu} + 31.998 \text{ amu} = 76.092 \text{ amu}[/tex]
Therefore, the total atomic mass is 76.092 amu.
Rounding to Meet Significant Figures RequirementsSignificant figures are used to determine the accuracy of a problem. A basic rule is to use scientific notation to determine how to meet the significant figure request. Since we are rounding to three significant figures, we want to make sure these three figures are significant. There are three basic rules to remember when computing significant figures:
Any zeroes to the left of the first non-zero number (ex: 0.0981) are insignificant.Any zeroes "trapped" in between other non-zero numbers (ex: 9.81075) are significant.Any zeroes to the right of the last non-zero number (ex: 5900) are significant ONLY IF they are added after a decimal point and included in the measurement (ex: 5900.)Therefore, since we need three significant figures, we have to round our value first and then determine the appropriate number of significant figures.
76.092 will round to 76.09 first, and then round to 76.1. We cannot use 76.09 since there is a trapped zero, which is considered significant.We must use 76.1 since there are three significant figures in the value.Final AnswerSince we have determined that 76.1 fits our requirements for three significant figures, we can safely determine that the molar mass of [tex]C_3H_8O_2[/tex], as determined, is 76.1 amu.
= 3 × Mass of C + 8 × Mass of H + 2 × Mass of O
= (3 × 12.01 + 8 × 1.008 + 2 × 15.999) g/mol
= (36.03 + 8.064 + 31.998) g/mol
= 76.092 g/mol
Answer:
76.092 g/mol
Hope you could get an idea from here.
Doubt clarification - use comment section.
Someone plz help me :(
Answer:B
Explanation:
Because that vaccine can help from people dieing.
Draw a sketch of a hot air balloon and of a helium balloon. Define the systems by identifying the system boundaries. Show inputs and outputs of matter and energy in each. Use your Evidence Notebook if necessary.
Explanation:
When you heat the air it expand its volume, but its mass remain the same, so the density of the hot air balloon is smaller than the density of the air outside it, so the hot air balloon can float.
In the case of the helium balloon, there's no source of energy, but the helium is naturally lighter than the atmospheric air, so its density is naturally smaller than the air, and the helium balloon have a smaller density than the air too, so it can float.
A closed system can interchange energy with its surrounding, but not matter.
A closed system can exchange energy but not matter, with its surrounding environment. The energy that enters into a closed system may derive from different forms (e.g., heat or work, kinetic energy)Conversely, an open system can exchange both energy and matter with its surrounding.In conclusion, a closed system can interchange energy with its surrounding, but not matter.
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what is the difference between a base and an alkaline
Answer:
Base Alkali
1)All bases are not alkali 1)All alkali are bases
2)It neutralizes acids 2) It releases OH- ions, accepts a proton
3)Example: Zinc hydroxide, copper oxide 3)Example: potassium hydroxide, sodium hydroxide
Please help me with this chemistry
Answer:
D=1.56g/mL
Explanation:
Density=m/v
D=14.06g/(24mL-15mL)
D=14.06g/9mL
D=1.56g/mL
Why water in a container is
Curved but not flat
Explain why the product at the negative electrode is not always a metal.
The product at the negative electrode is not always a metal because it will only be produced if it is less reactive than hydrogen.
What is a Metal?These are materials which donate electrons in a chemical reaction and have high heat and electrical conductivity.
Metals are more reactive than hydrogen which is why it is not always produced at the cathode.
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If scientists want to determine if a skin cream is effective against fighting acne, what would be the independent variable?
Answer:skin cream
Explanation:
the independent variable is the variable that is always changed or manipulated. in this case the skin cream is the independent variable.
What is Technology mean?
Answer:
The branch of knowledge dealing with engineering or applied sciences is called technology .
Hope this helps you!
any two uses of mixtures
Answer:
Any two used of mixtures are 1) sand and water 2) sugar and salt
Explanation:
ii. What is the purpose of the scientific method? (2 points)
b. Through his meticulous experiments, Lavoisier first proposed what is now known as the law of conservation of matter. A similar law developed later, which was called the law of conservation of energy. (6 points)
i. What does the law of conservation of energy say? (2 points)
ii. List two different kinds of energy. (2 points)
iii. What does the law say about changes energy can undergo? (2 points)
Answer:
ii. Purpose of scientific method
=The Scientific Method helps you put together experiments, use data to find conclusions and interpret them. In short, the Scientific Method is a step-by-step process: First, observe. Use your senses and take notes about the situation
The aim of all scientific methods is the same which is used to analyze the observation made at the beginning. It has been seen that various steps are adopted per the requirement of any given observation. Observation is the first step of scientific method.
What is scientific method?The process with the help of which scientists try to investigate, verify or construct an accurate and reliable version of any natural phenomena is defined as the scientific method. They are done by creating an objective framework for the purpose of scientific enquiry.
The purpose of scientific method is to provide discrete steps for analytically answering a research question. It involves the formulation of hypotheses and application to come up with logical explanations.
The scientific method establishes the facts through testing and experimentation. It involves prediction, conducting experiment and last analyze the results.
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Which of the following is a result of
condensation?
A. deserts
B. seasons
C. clouds
D. rocks
Answer: should be c. clouds :)
Explanation: condensation is the change of water to a gaseous form. it generally occurs in the atmosphere when warm air rises, cools, and loses its capacity to hold the water vapor. excess water vapor condenses to form cloud droplets.
Answer: clouds
Explanation: theyre air and water
You just created the equality 1 fluid oz f l u i d o z = 29.7 mL m L . Use this equality to determine how many ounces of water will be measured using the measuring cup introduced before Part A when making the cake. Keep in mind that the level of precision for the measuring cup is to the half-ounce as you round your answer.
The equality of both units (i.e. mL and ounces) implies they measure the same quantity, and they can be converted between one another.
Given that:
[tex]1 fl\ oz = 29.7mL[/tex]
The measurement in part A is not given. So, I will use an assumed value to provide an explanation.
Assume that the amount of water measured using the measuring cup in part A is 10mL
The equivalent number of ounces (x) is calculated as follows:
[tex]1 fl\ oz = 29.7mL[/tex]
[tex]x = 10mL[/tex]
Cross multiply
[tex]x \times 29.7mL = 1fl\ oz \times 10mL[/tex]
Cancel out common units
[tex]x \times 29.7 = 1fl\ oz \times 10[/tex]
[tex]x \times 29.7 = 10fl\ oz[/tex]
Divide both sides by 29.7
[tex]x = \frac{10}{29.7}fl\ oz[/tex]
[tex]x = 0.3367 fl\ oz[/tex]
Approximate to the nearest half
[tex]x = 0.5 fl\ oz[/tex]
This means that the equivalent amount of water is 0.5 ounces
What if the measurement is 55mL.
We apply the same steps, as follows:
[tex]1 fl\ oz = 29.7mL[/tex]
[tex]x = 55mL[/tex]
Cross multiply
[tex]x \times 29.7mL = 1fl\ oz \times 55mL[/tex]
Cancel out common terms
[tex]x \times 29.7 = 1fl\ oz \times 55[/tex]
[tex]x \times 29.7 = 55fl\ oz[/tex]
Divide both sides by 29.7
[tex]x= \frac{55}{29.7 }fl\ oz[/tex]
[tex]x= 1.85185 fl\ oz[/tex]
Approximate to the nearest half
[tex]x = 2fl\ oz[/tex]
This means that the equivalent amount of water is 2 ounces
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Bond order, bond length, and bond energy are closely related. The shorter a bond, the _____ its bond strength. A shorter bond will therefore have a higher bond energy than a longer bond. Bond order also plays a role. For a given pair of atoms, the higher the bond order, the shorter and _____ the bond will be.
Answer: greater, stronger
Explanation: Bonds that form as a result of sharing their electrons are called covalent bonds. A lot of energy is contained in those bonds, especially if they are higher order. A single bons is bond order 1, A triple bond is bond order 3. An example of a triple bond is acetylene. It combusts with a very hot flame when it's triple bond is broken with oxygen.
~Easy Points~.........what does H2o stand for ?
According to the Bohr model for the hydrogen atom, the energy of the atom isn't continuous but has certain discrete energy ________, each of which is related to a fixed circular _____________ of the electron around the nucleus. The farther the electron is from the nucleus, the ________ the energy system.
Answer:
in the part of material and also its gaining to support almost imaginary for all over of this things
A group of students conducted an experiment to determine the effect of heat on the germination(sprouting) of sunflower seeds. Which of the variables listed below is the least important to control in this experiment?
a
the temperature of which the seeds are heated
b
the length of time the seeds are heated
c
the type of soil used
d
the amount of moisture in the soil
what grade is this because apparently i like to know what grade it is before i solve it
What isotope will be formed by the fusion of a H-1 isotope and a H-3 isotope? Would the
product be a stable Isotope? Explain.
|
Answer:
Use the edit icon to pin, add or delete clips.
Explanation:
hfdknvd hcde