Answer:
Dissolves a chemical sample well at high temperatures.
Does not dissolve a chemical sample well at low temperatures.
Explanation:
Recrystallization involves the dissolution of the solute in a solvent at high temperature. As the solution cools, it becomes saturated and the solute crystallizes out of the solution.
A good recrystallization solvent must only dissolve the solute at high temperature and must not dissolve it at low temperature. Hence, these are the two conditions required for any good recrystallization solvent.
Observe: The Hollow pipe allows the water in each flask to move around and mix. Try several experiments with different temperatures in the top and bottom flasks.
Describe what you see
what is the state of the substance at room temperature (20°c)
Answer:
dez nuts. the forth quauter in ur girls buttr
Gas is well separated with no regular arrangement, liquids are close together and solids are tightly packed. Solid, liquid, and Gas are the state of substances at room temperature.
What is the state of substance?There are three state of substances:
solidLiquidGasThe chair you are sitting on is a solid, the water you drink is liquid, and the air you breathe is a gas. The atoms and molecules don't change, but the way they move about does. Water, for example, is always made up of two hydrogen atoms and one oxygen atom.
Physical properties of a particular substance determine its state at room temperature. If both its normal melting point and its normal boiling point are below room temperature (20°C), the substance is a gas under normal conditions.
Oxygen is a gas at room temperature. If the normal melting point of a substance is below room temperature, the substance is a liquid at room temperature.
If both the normal melting point and the normal boiling point are above room temperature, the substance is a solid.
Therefore, solid, liquid and gas all exist as substances at room temperature.
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Why are alkalis sometimes
described as the opposite of
acids?
Answer: Because Alkalis are bases that can dissolve in water, which can also neutralize acid.
Group of molecules which do not contain carbon
O enzymes
O inorganic compounds
O buffer
O elements
What is neither water nor land, and is always soaking wet?
Answer:
like mud
Explanation:
Answer:
wetland
Explanation:
a wetland is a region where water body meets land area
What angle is needed to spread 4 bonds as far apart as possible?
Answer:
109°
Explanation:
According to Valence Shell Electron Pair Repulsion Theory, electron pairs on the valence shell of the central atom of a molecule must be positioned as far apart in space as possible to minimize repulsion between valence shell electron pairs.
The shape of a molecule depends on the number and type of electron pairs on the valence shell of its central atom. Lone pairs generally cause more repulsion than bond pairs of electrons.
The ideal bond angle for a molecule with four bonds is 109° which corresponds to a tetrahedral geometry. This enables the four bonds to spread as far apart in space as possible.
(b) Draw the structure of the products when cyclopentene is reacted with:
(i) Cold alkaline KMnO4
Answer:
See explanation and image attached
Explanation:
When an alkene is reacted with cold, dilute and alkaline KMnO4, the product of the reaction is a 1,2-diol (vicinal diol). The products exhibit a “syn” stereochemistry with the addition of the two -OH groups to the same side of the alkene.
The reaction of cyclopentene with cold, dilute, alkaline KMnO4 is shown in the image attached.
In the given query, when cyclopentene is reacted with cold alkaline [tex]\rm KMnO_4[/tex], the product formed is cis-1,2-cyclopentanedicarboxylic acid (image attached below).
The reaction proceeds via oxidative cleavage of the double bond in cyclopentene to form two carboxylic acid groups.
The potassium permanganate ([tex]\rm KMnO_4[/tex]) acts as a strong oxidizing agent and cleaves the double bond to form two carboxylic acid groups.
The reaction can be represented as follows:
Cyclopentene + cold alkaline [tex]\rm KMnO_4 \rightarrow[/tex] cis-1,2-cyclopentanedicarboxylic acid
Therefore, the product, cis-1,2-cyclopentanedicarboxylic acid (refer to the attached image below), has a cyclopentane ring with two carboxylic acid groups attached to the 1 and 2 carbons, respectively.
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Some studies have found that when a person mimics an angry expression, their temperature actually rises.
O A True
OB.
False

Science is based primarily on peoples opinions and views of the subject matter.
True or false
Answer:
False
Explanation:
Science is not based on primarily on peoples opinions and views of the subject matter whereas science is based on empirical observations and research for its validity.
Science aims to find answers to human questions related to the natural world through their research observation and experiments. Scientists and researchers provide valid proof of human questions so that people can trust them.
Science can change people's opinions regarding the natural world with valid proof and observational theories but science is not based on people's opinion.
Hence, the given statement is "false".
1
Select the correct answer.
Which statement about the relationship between laws, hypotheses, and theories is true?
A.
Laws that remain true over an extended period of time are considered theories.
B.
A theory that holds true for a long time is considered a law.
C.
If a law is not contradicted after a lot of testing, it may be considered a hypothesis.
D.
If a hypothesis is not contradicted after a lot of testing, it may be considered a law.
Answer:
the answer is D
Explanation:
I need helpp!!!!!!!!!
Using the molecular weight (96.2 g/mol) determine the amount of mmol of (3S)-3,4- dimethylpentyne. Round to the tenths place.
Answer:
2.0 mmole
Explanation:
The computation fo the amount of mmol is shown below:
As we know that
[tex]Mole = \frac{Given\ mass}{molar\ mass}[/tex]
where,
Given mass is 0.2 gm
The Molar mass is 96.2g/mol
Now
put these values to the above formula
So,
[tex]= \frac{0.2}{y96.2} \\\\= \frac{1}{481} mole[/tex]
Mile mole is
[tex]= \frac{1}{481}\times 1,000[/tex]
= 2.079
= 2.0 mmole
As
mole = 1,000^-1 mili mole
We simply applied the above formula so that the amount of mmole could come
Which statement correctly compares an atom of an alkali metal with an atom of the alkaline earth metal next to it on the periodic table? aThe alkali metal atom forms a +1 ion, while the alkaline earth metal atom forms a +2 ion. bThe alkali metal atom forms a +2 ion, while the alkaline earth metal atom forms a +1 ion. cThe alkali metal atom has one less shell of electrons than the atom of the alkaline earth metal. dThe alkali metal atom has one more shell of electrons than the atom of the alkaline earth metal.
The atom of alkaline earth metal has one more proton and one more electron than the alkali metal that is next to it to the left on the periodic table. Then the atomic number of the alkali metal is one unit less than the atomic number of the alkaline earth metal next to it
Answer:
A) The alkali metal atom forms a +1 ion, while the alkaline earth metal atom forms a +2 ion.
Explanation:
Let's evaluate each answer.
A: The alkali metal atom forms a +1 ion, while the alkaline earth metal atom forms a +2 ion.
This means that the alkali metal atom has to lose 1 valence electron to form a +1 ion while the alkaline earth metal atom has to lose 2 valence electrons to form a +2 ion. This is accurate because alkali metal atoms have 1 valence electron while alkaline earth metal atoms have 2, so the statement is correct.
B: The alkali metal atom forms a +2 ion, while the alkaline earth metal atom forms a +1 ion.
This would mean that the alkali metal atom has to lose 2 valence electrons to form a +2 ion, while the alkaline earth metal has to lose 1 valence electron to form a +1 ion. This is incorrect because alkali metal atoms only have 1 valence electron and will become a +1 ion when losing that electron, while alkaline earth metals have 2 valence electrons and will form a +2 ion upon losing them.
C: The alkali metal atom has one less shell of electrons than the atom of the alkaline earth metal.
This would mean that the alkali metal atom would be located one period higher up than the alkaline earth metal atom. This is untrue, because the question states that the alkali metal atom is located directly next to the alkaline earth metal atom, so they have the same amount of electron shells.
D: The alkali metal atom has one more shell of electrons than the atom of the alkaline earth metal.
This would mean that the alkali metal atom would be located one period lower on the periodic table than the alkaline earth metal atom. Similar to the previous statement, this is untrue because the question states that they are located directly next to each other, or on the same period.
(Also, I just took this quiz and e2020 says it's right.)
11.In 13C NMR spectroscopy, the signal due to this type of carbon occurs furthest downfield.A)–CºNB)C)D)E)–CºC–
Answer:
C=O
Explanation:
The nuclear magnetic resonance (NMR) spectroscopy is a method that employs the technique to observe the local magnetic fields are atoms. This analytical technique exploits sufficient differences in the frequency of nuclear magnetic resonance in protons and atoms within organic compounds that depend on their neighboring atoms.
Amongst all the given options, the carbonyl is the right option because the carbon is doubly bonded to the oxygen and the hybridization of this double bond is sp² hybridized, as a result, the electron density at the carbon possess a lower amount in order to have more magnetic field.
The increasing order of these chemical shifts are as follows:
C - X < [tex]\mathbf{C -O }[/tex]≅[tex]\mathbf{ \mathrm{-C\equiv C-}}}[/tex] < -C≡N < C=O
HELPPP ANSWERS ????
A: 3
B: 2
C: 1
D: 4
Answer:
B. 2
Explanation:
We see from the reaction side of the equation that we have 2 Li. That means we need the same number of Li on the products side. Therefore, our only option is 2.
Answer:
b
Explanation:
Which four practices are examples of how humans use science?
A. Making decisions that help humans survive
OB. Developing technologies that help humans thrive
C. Developing explanations based on facts
D. Imagining entertaining stories that explain observations
O E. Gathering facts that explain natural events
Answer:
A. Making decisions that help humans survive
B. Developing technologies that help humans thrive
C. Developing explanations based on facts
E. Gathering facts that explain natural events
Explanation:
The above are examples of the practices of how humans use science.
Science has been of tremendous help to humans in making decisions that make humans survive and develop technologies that help humans thrive. It has helped to gather and develop explanations that are based on facts. It has helped to explain natural events.
which argument best explains the charge of an atomic nucleus
Answer:
An atomic nucleus is positively charged because it is composed of protons.
Explanation:
hope this helps you:)
Answer:
An atomic nucleus is positively charged because it is composed of protons.
Explanation: Just took test on edgenuity
Mendeleev's periodic table was organized by
mendeleev arranged the elements in order of increasing relative atomic mass. When he did this he noted that the chemical properties of the elements and their compounds showed a periodic trend
Answer:
Left to right
Elements are arranged by increasing atomic mass
What is the function of the magnet in NMR?
A) It limits the nuclear spin to certain allowed spin states.
B) It allows random orientation of nuclear magnetic moments.
C) It causes the nucleus to spin.
D) It holds the sample in place.
Answer:
A) It limits the nuclear spin to certain allowed spin states.
Explanation:
A nucleus with an odd atomic number or an odd mass number has a nuclear spin, which can be observed through NMR.
A proton is the simplest nucleus, and its odd atomic number of 1 implies that it has one spin. We can visualize a spinning proton as a positively charged rotating sphere. This movement of a charged particle is like an electric current in a wired loop. It generates a magnetic field called the magnetic moment. When a small magnetic bar is placed in the field of a larger magnet, it rotates to align itself with the field of the larger magnet, a lower energy arrangement than an orientation against the field. Quantum mechanics requires that the proton's magnetic moment is aligned with the external field or against the field. The lowest energy state with the proton aligned with the field is called the spin alpha state (α spin). The higher energy state with the proton aligned against the external magnetic field is called the beta spin state (β spin).
In the absence of an external magnetic field, the magnetic moments of the protons have random orientations. When an external magnetic field is applied, each proton in a sample it assumes β state or α state. Because the state of spin α is lower in energy, there are more α spins than β spins.
Because a gas has no definite volume or shape, in what way does it take up space? (2 points)
Group of answer choices
By taking the volume of a solid
By taking the volume of a liquid
By taking the shape of its container
By taking the volume of its container
Answer:
By taking the volume of the container.
Answer:
By taking the volume of the container
Explanation:
it does not have any specific volume or shape, so the way it volume is the volume of container.
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The transfer of thermal energy by particles moving through a fluid (either a
gas or a liquid) is called?
Answer:
Convection
Explanation:
Convection is the transfer of thermal energy by particles moving through a fluid.
Answer:
convection
Explanation:
trust
write a brief short note on translation and transcription?
Answer:
Transcription is when you make a copy of the RNA from DNA. This is how the mRNA can leave the nucleus which exists to the cytoplasm and into ribosomes where protein synthesis occurs. Translation is what happens after transcription and this is where protein synthesis occusrs in the ribosomes/endoplasmic reticulum.
Explanation:
What does green design refer to?
A. Using materials and design techniques that reduce the negative
environmental impact of a structure
B. Using innovative steel production, modern safety elevators, and
other engineering technologies
C. Using natural colors when designing building so that they don't
seem harsh against the natural landscape
D. Incorporating various materials' strengths and weaknesses in the
design process
SUBMIT
Answer:
A. Using materials and design techniques that reduce the negative
environmental impact of a structure
Explanation:
A P E X
Using materials and design techniques that reduce the negative
environmental impact of a structure. Hence, option A is correct.
What is green design?Green design is the 'creation of buildings which are energy-efficient healthy, comfortable, flexible in use and designed for long life.
The word ‘Green’ represents designs which are eco-friendly and less harmful to humans and other organisms. It helps in the protection of natural resources such as water, air etc.
Green designs are also referred to as techniques and materials that reduce the negative environmental impact of a structure.
Hence, option A is correct.
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Bismuth oxide reacts with carbon to form bismuth metal: Bi2O3(s) + 3C(s) → 2Bi(s) + 3CO(g) When 775 g of Bi2O3 reacts with excess carbon, (a) how many moles of Bi form? mol Bi (b) how many grams of CO form? g CO
Answer:
(a) 3.33 mol Bi
(b) 140. g CO
Explanation:
Step 1: Convert 775g to moles
Bi Molar Mass - 208.98 g/mol × 2 = 417.98 g/mol
O Molar Mass - 16.00 g/mol × 3 = 48.00 g/mol
775g Bi₂O₃ ÷ 465.98 g/mol = 1.66316 mol Bi₂O₃
Step 2: Find the conversion from Bi₂O₃ to Bi
1 mole of Bi₂O₃ equals 2 moles of Bi
Step 3: Use Dimensional Analysis
1.66316 mol · [tex]\frac{2 \hspace{2} mol \hspace{2} Bi}{1 \hspace{2} mol \hspace{2} Bi_2O_3}[/tex] = 3.32632 mol Bi
3.32632 mol Bi ≈ 3.33 mol Bi (3 significant figures)
Step 4: Find the conversion from Bi₂O₃ to CO
1 mole of Bi₂O₃ equals 3 moles of CO
Step 5: Use Dimensional Analysis
1.66316 mol · [tex]\frac{3 \hspace{2} mol \hspace{2} CO}{1 \hspace{2} mol \hspace{2} Bi_2O_3}[/tex] = 4.98948 mol CO
Step 6: Find molar mass of CO and convert moles to grams
C - 12.01 g/mol
O - 16.00 g/mol
4.98948 mol CO · 28.01 g/mol = 139.775 g CO
139.775 g CO ≈ 140. g CO (3 significant figures)
Students observed cells under the microscope. They observed that the cells had a cell wall, cell membrane,
nucleus, and many chloroplasts.
Which observation helps students identify the type of cell observed?
A The presence of a nucleus means the cells are from a plant.
B The presence of a cell membrane means that the cells are from an animal.
C The presence of chloroplasts means that the cells are from a plant.
D The presence of a cell wall means that the cells are from an animal.
Answer:
option B is the right answer
Uranium is a type of atom. In special circumstances that usually involve high amounts of energy, uranium can be broken. When this occurs, different pieces of the original atom remain, including a substance called plutonium. Which statement most likely describes plutonium? It will still be uranium, just smaller pieces of uranium. It must no longer be a form of matter. It must be a different kind of atom. It will be different than, but have the same properties as, uranium.
Answer:
It's c
Explanation:
I'm taking the test now on edge.
It must be a different kind of atom statement mostly likely describes plutonium. Hence option C is correct.
What are atoms?It is the smallest unit of matter that possess the properties of the chemical element. It can’t be an independently, they form ions and molecules they both are combine and form large numbers of matters.
Atoms are basically three types: Neutrons, protons and electrons.
In periodic table plutonium is above uranium. Plutonium is more powerful as compared to uranium because it is an isotope and more radioactive.
Almost all of naturally occurring. Uranium 92U238with a half-life of 4.468 x 109 year. Most rest of the natural uranium is92U235.
Uranium is generally used in the process of nuclear fission whereas plutonium is used for the production of nuclear weapons.
It must be a different kind of atom statement mostly likely describes plutonium. Hence option C is correct.
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Explain the role that gravitation played in the formation of the Moon after the large planetesimal hit Earth.
Answer:
The gravity pulled the bits back and formed a ball which is the moon
Explanation:
hope this helps :)
Answer:
While some of the debris from the collision merged back into Earth, the gravity caused the accretion of much of the debris into a separate ball, forming the Moon.
Explanation:
Determine the pH of 023M HNO3 solution.
Answer:
pH = 1.683
Explanation:
plz mark as brainliest if it helps
A certain substance X has a normal freezing point of −3.1°C and a molal freezing point depression constant =Kf·6.23°C·kgmol−1. Calculate the freezing point of a solution made of 12.3g of urea NH22CO dissolved in 300.g of X. Be sure your answer has the correct number of significant digits.
Answer:
Freezing T° of solution = - 7.35 °C
Explanation:
This is about the freezing point depression, a colligative property which depends on solute.
The formula is: Freezing T° pure solvent - Freezing T° solution = m . Kf . i
Freezing T° of pure solvent is -3.1°C
At this case, i = 1. As an organic compound the urea does not ionize.
We determine the molality (mol/kg of solvent)
We convert mass to moles:
12.3 g . 1mol / 60.06 g = 0.205 moles
0.205 mol / 0.3 kg = 0.682 mol/kg
We replace data in the formula:
-3.1°C - Freezing T° of solution = 0.682 mol/kg . 6.23 kg°C/mol . 1
Freezing T° of solution = 0.682 mol/kg . 6.23 kg°C/mol . 1 + 3.1°C
Freezing T° of solution = - 7.35 °C
Oxidation state of N in n2(g)
Answer:
0
Explanation:
did research