Answer:
A. Controlled variable
Explanation:
a controlled variable or a constant variable is a variable that doesnt change during an experiment
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.)
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.
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)
What percentage of light hits Earth’s surface directly?
3 percent
5 percent
31 percent
47 percent
Answer: yall trust me on this one, i took one for the team. The answer is "C" or you can say 31 percent. boys get me 50 thanks.
Explanation:
The percentage of sunlight that hits the Earth's surface directly is 31 percent. The correct option is C.
What is sunlight?Sunlight is the electromagnetic radiation transferred by the sun.
The sun is 93 million away from the earth, so it takes eight and half minutes to reach the sunlight to the earth.
Only 30 to 34 percent of light reaches the earth, and the remaining lights are reflected back by clouds and the earth itself.
Thus, the correct option is C, 31 percent.
Learn more about sunlight
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Group of molecules which do not contain carbon
O enzymes
O inorganic compounds
O buffer
O elements
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.
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
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
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".
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.
Learn more about green design here:
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I need helpp!!!!!!!!!
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:
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
Akito is warming a test tube over a Bunsen burner. He heats it too much and the glass breaks.
Which best describes what Akito should do first?
Ο Ο Ο Ο
O get paper towels
O change lab stations
turn off the burner
remove his contacts
Answer:
c
Explanation:
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
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.
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 of the following is not true about water ? *
Water has a freezing point of 0℃
Water is chemically stable and makes a good energy source
Water has a density of 1 g/mL
water is polar
water has a boiling point of 100℃
Water is less dense as a solid
In which field(s) is knowledge about how science works important?
A. Medicine
B. All of these are correct
C. Law
D. Politics
E. Agriculture
Answer:B
Explanation:
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
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 of the following experimental methods cannot be used to measure the rate of a reaction? Group of answer choices measurement of the absorbance of a colored reactant with time measurement of the change in the partial pressure of a gas-phase product over time measurement of the equilibrium concentration of an acidic product via titration with a strong base measurement of the absorbance of a colored product with time measurement of the change in the partial pressure of a gas-phase reactant over time
Answer:
measurement of the equilibrium concentration of an acidic product via titration with a strong base
Explanation:
The rate at which a reaction proceeds refers to how quickly the reaction is occuring. In other words, it is how quickly the reactants are changing to the products. According to the question, the rate of a reaction can be measured experimentally using the reactants' or products' properties e.g volume, pressure etc.
Since reactions must involve reactants and products, the manner in which either the reactants or products changes over time can be measured. For example; measurement of the absorbance of a colored reactant or product with time, measurement of the change in the partial pressure of a gas-phase reactant or product over time can be used.
However, a measurement of the equilibrium concentration of an acidic product via titration with a strong base will not tell us how fast the reaction is going because it is in an EQUILIBRIUM state i.e. reaction is occuring at an equal rate
In the density of a liquid activity, the graph had an intercept. If you were to make a similar graph using metal blocks, would the graph have an intercept?
Answer:
NO
Explanation:
It would be difficult to plot a line of best fit on the scattered graph of the activities of metal blocks as the activities would almost be the same horizontally on the graph and an attempt to draw/determine an intercept will be almost impossible. The line of best fit is usually drawn to determine the relatedness/correlation of the variables.
Drawing intercept for the activities of the liquid is easier because a line of best fit can be easily placed between the clustered liquid activities on the scattered plot.
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:
Determine the pH of 023M HNO3 solution.
Answer:
pH = 1.683
Explanation:
plz mark as brainliest if it helps
Describe the evidence for Mercury having a molten iron core
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.
Oxidation state of N in n2(g)
Answer:
0
Explanation:
did research
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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