Câu 3: Nêu phương pháp hóa học nhận biết các dung dịch không màu sau: (a) HCI, NaOH, H2SO,, NaCl. (b) HNO3. KOH, BaCl. Ca(OH)2. Ba(NO3)2 (c) MgCl2, KCl, CuCl2, FeCl3, FeCl2 (chỉ dùng một thuốc thử). (d) Na2CO3, BaCl2, NaNO3 (chỉ dùng một thuốc thử)
Answer:
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Helium is in group 18 of the periodic table. How is helium different from the other elements in this group?(1 point)
A _ Helium atoms have a full outer energy level, while atoms of the other elements in the group do not have a full outer energy level.
B _ Helium atoms have 2 electrons, while atoms of the other elements in the group all have 18 electrons.
C _ Helium atoms have 2 valence electrons, while atoms of the other elements in the group all have 8 valence electrons.
D _ Helium atoms have valence electrons in the first energy level, while atoms of the other elements in the group have valence electrons in the second energy level.
The correct answer to the question is option C. Helium atoms have 2 valence electrons, while atoms of the other elements in the group all have 8 valence electrons.
Group 18 of the periodic table are known as the noble gas family. Their outermost shell is completely filled.
Members of the group 18 includes:
1. Helium (He)
2. Neon (Ne)
3. Argon (Ar)
4. Krypton (Kr)
5. Xenon (Xe)
6. Radon (Rn)
Among this group, only Helium (He) has a valence electron of 2. Other members of the group has a valence electron of 8.
Helium is part of the group 18 because its outermost shell is completely filled by its 2 electrons.
Therefore, option C gives the right answer to the question as helium only have 2 valence electrons while other members of the group has 8 valence electrons.
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Identify the more polar bond in each of the following pairs of bonds:
a. HF or HCl
b. NO or CO
c. SH or OH
d. PCl or SCl
e. CH or NH
f. SO or PO
g. CN or NN
Answer:
a.HF
b.co
c.oH
d.pcl
e.NH
f.po
g.CN
a) Among HF or HCl the more polar bond is HF. b) Among NO or CO, the more polar bond is CO. c) Among SH or OH, the more polar bond is OH. d) Among PCl or SCl, the more polar bond is PCl. e) Among CH or NH, the more polar bond is NH. f) Among SO or PO, the more polar bond is SO. g) Among CN or NN, the more polar bond is CN.
To determine the more polar bond in each pair, we need to consider the electronegativity difference between the bonded atoms. The greater the electronegativity difference, the more polar the bond. Electronegativity is a measure of an atom's tendency to attract electrons towards itself in a chemical bond.
The electronegativity values (Pauling scale) for the elements involved in the bonds are:
H = 2.20
F = 3.98
Cl = 3.16
N = 3.04
O = 3.44
S = 2.58
P = 2.19
C = 2.55
a. HF or HCl
HF: Electronegativity difference = 3.98 - 2.20 = 1.78
HCl: Electronegativity difference = 3.16 - 2.20 = 0.96
The more polar bond is HF.
b. NO or CO
NO: Electronegativity difference = 3.04 - 2.55 = 0.49
CO: Electronegativity difference = 3.44 - 2.55 = 0.89
The more polar bond is CO.
c. SH or OH
SH: Electronegativity difference = 2.58 - 2.20 = 0.38
OH: Electronegativity difference = 3.44 - 2.20 = 1.24
The more polar bond is OH.
d. PCl or SCl
PCl: Electronegativity difference = 3.16 - 2.19 = 0.97
SCl: Electronegativity difference = 3.16 - 2.58 = 0.58
The more polar bond is PCl.
e. CH or NH
CH: Electronegativity difference = 2.55 - 2.20 = 0.35
NH: Electronegativity difference = 3.04 - 2.55 = 0.49
The more polar bond is NH.
f. SO or PO
SO: Electronegativity difference = 2.58 - 3.44 = -0.86
PO: Electronegativity difference = 2.19 - 3.44 = -1.25
The more polar bond is SO.
g. CN or NN
CN: Electronegativity difference = 3.44 - 2.55 = 0.89
NN: Electronegativity difference = 3.04 - 3.04 = 0
The more polar bond is CN.
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what is the volume of a substance with a mass of 64.9 g/ and a density of 2.1 g/ml?
Classify the following properties of the element
silicon as chemical or physical properties:
a. blue-gray color
b. brittle
c. doesn't dissolve in water
d. melts at 1410°C
e. reacts vigorously with fluorine
We have that this how they differ
Physical properties
Blue-gray color BrittleChemical Properties
Doesn't dissolve in water Melts at 1410°C Reacts vigorously with fluorine
From the Question we are told that
Silicon properties:
a. blue-gray color
b. brittle
c. doesn't dissolve in water
d. melts at 1410°C
e. reacts vigorously with fluorine
Physical properties
This Refer to Properties that can be seen and Measured
While
Chemical Properties
This are Refers to the effect of the element in reactions
Therefore
Physical properties
Blue-gray color BrittleChemical Properties
Doesn't dissolve in water Melts at 1410°C Reacts vigorously with fluorineFor more information on this visit
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Acrylonitrile and ethyl acetate have the same boiling point: 77.2°C. In one to two sentences, explain what outcome you would expect if a
mixture of these two substances were distilled.
plsss hurry!
Acrylonitrile and ethyl acetate can not be separated by simple distillation since they have the same boiling point.
Distillation is a separation technique in chemistry which can be applied only when the substances to be separated have different boiling points. The method relies on the difference between the boiling points of the components of a mixture in order to achieve separation.
Whereby Acrylonitrile and ethyl acetate have the same boiling point: 77.2°C, separation by distillation becomes impossible because the two substances are collected together.
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aluminum is above carbon in the reactivity series.Explain why the aluminum in aluminum oxide cannot be extracted using carbon.
Aluminum is too high in the electrochemical series (reactivity series) to extract it from its ore using carbon reduction. The temperatures needed are too high to be economic. ... The aluminum oxide has too high a melting point to electrolyse on its own. The usual aluminum ore is bauxite.
What is a claim? (Please check all that apply)
An answer to a question that's asked.
A fact you're asserting is true.
Data from graphs and observations.
An explanation.
Answer:
Claim: It is an answer to your question
Explanation:
4. List three (3) safety rules when using a Bunsen burner.
1.
2.
3.
Answer:
1. place the bunsen burner away from any overhead shelving, equipment or lights by at least 1 foot.
2. remove all un-needed supplies and excess chemicals from the area.
3. tie-back any long hair, take off loose jewlery, or change out of loose clothing.
List nonscientific careers that use chemistry.
Non scientific careers are the careers that do not involve a person studying science courses or pursuing fields related to sciences.
Some of the nonscientific careers that use chemistry include:
Astrophysicist: An individual who studies the universe and its contents, such as the planets, stars etc. ProfessorSales: Those in the sales department may be involved in the use of chemicals.LawyerChefFarmer: A farmer can make use of chemicals such as herbicides, pesticides etc in controlling herbs and pests in his farm.Technical Writer: A writer may need to study and learn about a chemical or make use of it for his writing purpose.Read related link on:
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En la practica de la papa,¿a que atribuyes el hecho de la rapidez de reacción?
Answer:
El rendimiento de tubérculos de la papa es vulnerable a las altas temperaturas y se ve desafiado por el aumento asimétrico de las temperaturas diurnas y nocturnas. Este estudio tuvo como objetivo evaluar la fotosíntesis, el crecimiento de biomasa, la distribución de la masa de tubérculos y el rendimiento de tubérculo seco en papas cosechadas temprano que se cultivaron en el campo bajo condiciones de alta temperatura diurna y nocturna durante diferentes etapas de crecimiento.
Classify vodka (composed of 50% water and 50% alcohol).
Answer:
Liquor
Explanation:
Jane and Jack have a bicycling competition Jane rides a constant speed of 12 miles per hour while Jack rides at a constant speed of 330 feet per minute. How fast are Jane and Jack going in meters per second? Who finishes first? Show your factor-label method work. There are 5280 feet in one mile. There are 3.281 feet in one meter
Answer:
Explanation:
I don't know how you want the conversion done. I use dimensional analysis.
Jane
12 miles / hour [1.6 km/1 mile][1000 m/1 km][1 hour / 3600 sec]
12 * [1.6 * 3600 / 1000 m/s] = 69.12 m/s
5.33 m/s This answer is a bit shorter than using 5280 feet.
Using 5280 feet
12 miles / hour [5280 ft/1 mile] [1 m/3.281 feet] * [1 hr/3600 sec]
12 * 5280 / (3.281 * 3600)
12 *. 4470
5.36
Jack
330 feet / minute [ 1 meter / 3.281 feet] [1 minute / 60 seconds]
330 * 1/(3.281 * 60)
330 * 1/(196.86)
1.676 m/s
She's going faster than he is, no matter which method is used to do the calculation
Express 0.021 in scientific
notation.
[ ? ]10
Answer:
0.021 in scientific notation is 2.1 x 10^-2
Explanation:
Since there are two zeros before the non-zero digits, 10 should be raised to -2.
hope this helps
Using scientific notation, one can express extremely big or extremely small values. When a number between 1 and 10 is multiplied by a power of 10, the result is represented in scientific notation. 0.021 in scientific notation is 2.1 x 10⁻².
A way to express numbers that are either too large or too little to be conveniently stated in decimal form is through scientific notation. It is also known as "scientific form" in Britain, because scientists, mathematicians, and engineers frequently use it for intricate calculations involving large numbers.
A condensed manner of writing numbers is known as scientific notation (also known as standard form). A number is represented by a number from 1 to less than 10, multiplied by a power of 10, when it is written in scientific notation.
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What did the Copernican revolution demonstrate?
A. That science was limited to theories that could be tested
B. That science was a process of changing ideas
C. That science was only accurate when expensive equipment was
used
D. That science was not reliable and could not be trusted
Answer:
i think it's B.
Explanation:
i know that one of them is multiple choice but i’m not sure which one it is.
Explanation:
1. neutrons
2. protons
3. protons and neutrons
4. neutrons
5. electrons
I'm not sure with 1 and 4, sorry :<
Milk Souring
a
Chemical Change
b
Physical Change
Answer:
Chemical Change
Explanation:
It is a chemical change because milk is a substance and if it changes its molecular structure ,so it is a chemical change.
Voyager 2 traveled approximately 4.4 billion miles in 2.0 years. What was Voyager 2's average speed expressed in m/s?
The average speed of a body is the ratio of distance covered to time taken.
From the question, we have the following parameters;
Distance covered = 4.4 * 10^9 miles or 7081.1136 meters
Time taken = 2.0 years or 6.307 * 10^7 seconds
Average speed = Distance covered/ Time taken
Average speed = 7081.1136 meters/6.307 * 10^7 seconds
Average speed = 1.12 * 10^-4 m/s
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What does science mean to you?
Answer:
The study of properties for all things living and non-living
Which option is an isotope with 6 protons and 8 neutrons?
* oxygen-6
* oxygen-14
*carbon-14
*carbon-8
Answer:
carbon-14
Explanation:
becouse protons and neutrons are nagetivly charged
You push a shopping cart for fun with a force of 60N. If the shopping cart has a mass of 12kg, what is the acceleration on the cart
Answer:
[tex]\boxed {\boxed {\sf 5 \ m/s^2 }}[/tex]
Explanation:
We are asked to find the acceleration of a shopping cart, given the force and mass. According to Newton's Second Law of Motion, force is the product of mass and acceleration.
[tex]F= m \times a[/tex]
The mass of the shopping cart is 12 kilograms and the force is 60 Newtons. Let's convert the units for force. 1 Newton is equal to 1 kilogram meter per second squared, so the force of 60 Newtons is also 60 kilogram meters per second squared.
F= 60 kg*m/s²m= 12 kgSubstitute the values into the formula.
[tex]60 \ kg *m/s^2 = 12 \ kg \times a[/tex]
We are solving for the acceleration, so we must isolate the variable a. It is being multiplied by 12 kilograms. The inverse operation of multiplication is division, so we divide both sides by 12 kg.
[tex]\frac {60 \ kg *m/s^2 } { 12 \ kg}= \frac{12 \ kg \times a }{12 \ kg}[/tex]
[tex]\frac {60 \ kg *m/s^2 } { 12 \ kg}=a[/tex]
The units of kilograms cancel.
[tex]\frac {60 \ m/s^2 } { 12 }=a[/tex]
[tex]5 \ m/s^2 =a[/tex]
The acceleration of the shopping cart is 5 meters per second squared.
Negative effects on farming. Atleast 10 negative effects
(marks 10)
Answer:
climate change, dead zones, genetic engineering, pollutants, deforestation, soil degradation, waste, Over irrigation, salt buildup in soils, monoculture
Explanation:
Hopefully this'll help you!
What series does the following compound belong to?
will mark brainliest if correct
Answer:
1. Evaporation
2. Filtration
3. Distillation
4. Chromatography
Explanation:
[tex].[/tex]
0.0702 divided by 1.35
Answer:
0.052
Explanation:
0.0702 / 1.35 = 0.052
Measurements of the heights of various plants in an experiment are called
Answer:
Option 1 Data
Answer:
data
Explanation:
that is the answer
please 5 stars
what is atomic weight?
Answer: The sum of an atom's protons, neutrons, and electrons, with protons equal to 1 AMU each, and electrons are 0 AMU each.
Explanation: By convention, atomic mass of an element is calculated by adding the masses of it's protons, neutons, and electrons. By definition, protons and neutrons are assigned values of 1 "atomic mass unit," or AMU, each, and electons are so small that they are assigned a value of 0 AMU each. Thus, a carbon 12 isotope atom (6 protons, 6 neutrons, and 6 electrons) would have a total of (6+6+0 =) 12 AMU. Carbon-13 has an additional neutron, so it's mass is (6+7+0)= 13 AMU. Molecules are the sum of each of it's individual atoms.
What is an AMU in actual mass? The definition states that 1 AMU is 1/12 the mass of a sinlge Carbon 12 isotope. By defining it in this manner, independent laboratories can calibrate their own instruments with a universal standard. Yes, even the Klingons can calibrate in their own galaxy, far, far away. For those physicists who know the value of even small amounts of mass, 1 AMU is equal to 1.66054x10^-24 grams. Before you scoff, just be reminded that E=mc^2, so while m, mass, may be small, c^2 (speed of light squared) is very large.
What kind of mixture is a graham cracker?
Answer:
so here is the answer (What kind of a question my freind
Explanation:
Graham crackers are a whole wheat sweet cookie used in baking and making S'mores. Did you know that Graham crackers are called that because they're made from Graham Flour? It's a flour similar to conventional whole wheat flour in that both are made from the whole grain, but Graham flour is ground more coarsely.
What is the density of water (in g/mL) to four significant figures at 20°C?
ANSWER:
I calculated it in g/cm^3, It equals 0.9982 g/cm^3
The density of water at 20°C is found to be 0.9982 g/mL.
What is Density?Density may be defined as the classical measurement of quantity or mass per unit of volume in a particular substance. According to mathematics, density is simply characterized as mass divided by volume. That is:
[tex]Density = \frac{Mass }{Volume }[/tex]
Density typically describes how much space an object or substance takes up in relation to the amount of matter in that object or substance.
Density only significantly depends on the mass of the body as well as the volume occupied by it. The SI unit of density is kg/[tex]m^3[/tex]. The density remarkably does not vary much with respect to the temperature.
Therefore, the density of water at 20°C is found to be 0.9982 g/mL.
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What begins the combustion phase of a four-stroke engine cycle?
A. The air-fuel mixture is compressed.
O
B. An air-fuel mixture flows into the cylinder.
O
C. The air-fuel mixture is ignited.
O
D. The air-fuel mixture expands.
Answer: B
Explanation: The engine cycle begins with the intake stroke as the piston is pulled towards the crankshaft (to the left in the figure). The intake valve is open, and fuel and air are drawn past the valve and into the combustion chamber and cylinder from the intake manifold located on top of the combustion chamber.