Answer:Boiling point of a solution is found to be 100.34
o
C. Boiling point of pure
water is 100
o
C.
The elevation in the boiling point ΔT
b
=100.34−100=0.34
o
C.
12 gm glucose (molecular weight 180 g/mol) is dissolved in 100 gm water.
The number of moles of glucose =
180g/mol
12g
=0.0667mol
Mass of water =100g×
1000g
1kg
=0.100kg
Molality of solution m=
0.100kg
0.0667mol
=0.667mol/kg
The elevation in the boiling point ΔT
b
=K
b
×m
0.34
o
C=K
b
×0.667mol/kg
K
b
=0.51
o
Ckg/mol
The molal elevation constant for water is 0.51
o
Ckg/mol.
Explanation:
Q
a. Ahmed worked on his crops of wheat and maize to produce a better-quality crop (which gives a more yield). In detail, write down how he altered his crop into a better yielding crop.
b. What is the name of the process that Ahmed used to breed his new better-quality wheat and maize.
Answer:
.
Explanation:
1. Kaleigh notices when she goes to the beach that sometimes the water rises as high as the pier. At other times of the day, the water barely covers the pillars under the pier. These differences in water level are primarily due to the gravitational influence of which of the following?
a. The Earth’s revolution b. The Moon c. asteroids d. comets
may we met again !
i love you,ella
Answer: When I see you again!
Explanation:
What does a salt bridge do?
A. It supplies energy to make the redox reaction happen.
B. It supplies the electrolyte solutions with metal ions.
C. It creates a path for metal ions to flow from anode to cathode.
D. It prevents charges from building up in the solutions.
Answer:
D. It prevents charges from building up in the solutions :)
Explanation:
A P E X
Consider the balanced equation. PCl3 + 3H2O Right arrow. H3PO3 + 3HCl What is the percent yield of HCl if 42.0 g of HCl are produced from the reaction of 62.0 g of PCl3? Use Percent yield equals StartFraction actual yield over theoretical yield EndFraction times 100..
Answer:
Percient yield of reaction: 85 %
Explanation:
The reaction is:
PCl₃ + 3H₂O → H₃PO₃ + 3HCl
We only have data from the chloride, so we assume water is in excess. We convert the mass to moles:
62 g . 1mol / 137.32 g = 0.452 mol
If ratio is 1:3, from 0.452 mol we would produce three times as big, that amount. (0.452 . 3) = 1.36 moles of HCl.
We convert the amount to mass.
1.36 mol . 36.45g / 1mol = 49.4 g
This value of produced HCl is the theoretical yield. To determine the percent yield we make:
(Yield produced / Theoretical yield) . 100
(42 g / 49.4g) . 100 = 85%
Answer:
Yes it is 85.0%
Explanation:
If there are 400 radioactive atoms in a sample, how many will remain after four half-lives have passed?
Enter the exact number as your answer. Do not spell out the number.
Answer:
25 atoms
Explanation:
Given data:
Total number of atoms = 400 atom
Atoms remain after 4 half lives passed = ?
Solution:
At time zero = 400 atom
At first half life = 400 atom/2 = 200 atom
At 2nd half life = 200 atom/2 = 100 atom
At 3rd half life = 100 atom/2 = 50 atom
At 4th half life = 50 atom/2 = 25 atom
Thus, 25 atoms are remained after 4 half lives.
25 atoms of the radioactive atoms will remain after 4 half lives.
Given in the question,
Initial amount of a radioactive element = 400 atomsNumber of half lives = 4Expression for the amount remaining of a radioactive element after 'n' half lives is given by,
[tex]N=N_0(\frac{1}{2})^n[/tex]
Here, [tex]N_0=[/tex] Initial amount
[tex]n=[/tex] Number of half lives
By substituting the vales of [tex]N_0[/tex] and [tex]n[/tex] in the question,
[tex]N=400(\frac{1}{2})^4[/tex]
[tex]=\frac{400}{16}[/tex]
[tex]=25[/tex]
Therefore, 25 atoms of the radioactive atoms will remain after 4 half lives.
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A mixture contains 21.7 g NaCI, 3.74 g KCI, and 9.76 g Lici. What is the mole fraction of NaCl in this mixture?
Molar mass
NaCl: 58.44g/mol
KCl: 74.55g/mol
LiCl: 42.39g/mol
Answer:Mole Fraction of NaCl=0.5697
Explanation:
No OF Moles of NaCl= Mass / Molar mass
=21.7 g/58.44g/mol
=0.371moles
No OF Moles of KCl= Mass / Molar mass
=3.74g/74.55g/mol
=0.0502moles
No OF Moles of LiCl= Mass / Molar mass
=9.76 g/42.39g/mol
=0.230moles
Mole Fraction of NaCL = Moles of NaCL/ Total number of moles of the mixture
=0.371/( 0.371+ 0.0502+0.230)
0.371/0.6512
=0.5697
Answer:
Mole fraction: 0.570
Explanation:
Mole fraction is defined as the ratio of moles of a compound in a mixture over the total moles of the mixture. To solve this problem, we need to find moles of the 3 salts:
Moles NaCl -Molar mass: 58.44g/mol-:
21.7g NaCl * (1mol / 58.44g) = 0.3713 moles
Moles KCl -Molar mass: 74.55g/mol-:
3.74g KCl * (1mol / 74.55g) = 0.0502 moles
Moles LiCl -Molar mass: 42.394g/mol-:
9.76g LiCl * (1mol / 42.394g) = 0.2302 moles
Mole fraction NaCl:
0.3713mol / (0.3713mol + 0.0502mol + 0.2302mol) =
0.570
A hot metal plate at 150°C has been placed in air at room temperature. Which event would most likely take place over
the next few minutes?
O Molecules in both the metal and the surrounding air will start moving at lower speeds.
O Molecules in both the metal and the surrounding air will start moving at higher speeds.
O The air molecules that are surrounding the metal will slow down, and the molecules in the metal will speed up.
O The air molecules that are surrounding the metal will speed up, and the molecules in the metal will slow down.
Answer:
It would be the third answer.
Explanation:
This is because over the next few minutes, the heat would radiate away from the atoms in the metal plate and the atoms around the plate would absorb this radiation.
How are the cells of the bicep muscle similar to the cells of the heart muscle?
A. They digest food.
B. They make energy.
C. They use carbon dioxide.
D. They form tissue that moves.
Answer:
I believe it's D
Explanation:
they both are worked a lot and it makes the most sense.
The cells in both bicep muscle and heart muscle make energy for contraction and relaxation. Hence, option B is correct.
What is cardiac muscles ?Cardiomyocytes have a rather rectangular form and are short and thin. They have a single nucleus, cell organelles that are identical to those seen in skeletal muscle cells, and many sarcosomes, which supply the energy needed for contraction.
Intercalated discs with gap junctions for diffusion and communication link cardiomyocytes structurally. Myofibrils, which in turn are composed of thick and thin myofilaments, make up the sarcoplasm.
Due to their high energy needs, skeletal muscle cells have many mitochondria that enable them to produce enough ATP. Therefore, the cells in the bicep muscles and cardiac muscles produce energy.
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Balance the following equations:
i. H2SO4 + ….NaHCO3 → Na2SO4 + ….H2O + ……CO2
ii. H2 + I2 → ….HI
iii. …..NaOH + H2SO4 → Na2SO4 + …..H2O
iv. ……FeSO4 → Fe2O3 + SO2 + SO3
v. C3H6O2 + …..O2 → ….CO2 + …..H2O
b) Calculate the molecular masses of the following:
i. H2SO4
ii. CH4
iii. NH3
c) 56g of iron reacts with 71g of chlorine. How many grams of iron react with 35.5g of chlorine?
(I) [tex]H_2SO_4+ 2NaHCO_3--> Na_2SO_4 + 2 H_2O + 2CO_2[/tex]
(II) [tex]H_2+I_2 --> 2HI[/tex]
(III) [tex]2NaOH+H_2SO_4--> Na_2SO_4+ 2H_2O[/tex]
(IV) [tex]2FeSO_4--> Fe_2O_3+SO_2+SO_3[/tex]
(V) [tex]2C_3H_6O_2+7O_2-->6CO_2+6H_2O[/tex]
_____________________________________Molecular Masses of the following:------------------------------------------------------------------------------------------------------------
(I) [tex]H_2SO_4[/tex]
(ANS) [tex]98 \frac{grams}{mol}[/tex]
__________________________________________________________
Solution:
Molecular mass of,
H = 1
S = 32
O = 16
Now,
There are 2 atoms of Hydrogen, 1 atoms of Sulfur and 4 atoms of Oxygen present, thus,
[tex]H_2SO_4 = (1x2)+32+(16x4)[/tex]
[tex]H_2SO_4 = 98 \frac{grams}{mol}[/tex]
_____________________________________(II) [tex]CH_4[/tex]
(ANS) [tex]16 \frac{gram}{mol}[/tex]
_________________________________________________________
Solution:
Molecular Mass,
Carbon = 12
Hydrogen = 1
Now
There are 1 atom of Oxygen and 4 atoms of Hydrogen present, thus,
[tex]CH_4 = 12 + (1x4)[/tex]
[tex]CH_4 = 16\frac{grams}{mol}[/tex]
_____________________________________(III) [tex]NH_3[/tex]
(ANS) [tex]17 \frac{grams}{mol}[/tex]
__________________________________________________________
Solution:
Molecular Mass,
Nitrogen = 14 grams
Hydrogen = 1
Now,
There are 1 atoms of Nitrogen and 3 atoms of Hydrogen present, thus,
[tex]NH_3 = 14 + (1x3)[/tex]
[tex]NH_3 = 17 \frac{grams}{mol}[/tex]
_____________________________________How many Grams of Iron(fe):[tex]Fe + Cl_2 --> FeCl_2[/tex]56 71
x 35.5
_____________________________________[tex]X = \frac{56 x 35.5}{71}[/tex]
Simplify the equation
X = 28 grams
__________________________________________________________
Answer:
28 grams of Iron(fe) will react with chlorine.
_____________________________________Best Regards,'Borz'Which statement about plant and animal cells is true? A. Plant cells have a nucleus and a cell wall; animal cells do not have either of these structures. B. Plant cells have a cell wall and chloroplasts; animal cells do not have either of these structures. C. Plant cells have a cell wall and a cell membrane; animal cells have a cell wall but not a cell membrane. D. Plant cells have chloroplasts and mitochondria; animal cells have chloroplasts but do not have mitochondria.
Answer:
B. Plant cells have a cell wall and chloroplasts; animal cells do not have either of these structures.
Explanation:
A major difference between a plant cell and an animal cell is presence of chloroplasts in plant cells. Another key difference between plant and animal cells is the presence of a cell wall in plant cells. Both structures are absent in an animal cells.
The cell wall surrounds the plasma membrane of plant cells. This helps to provide the required tensile strength and protection against mechanical and osmotic stress.
Cell walls also help plants to maintain shape and rigidity.
The plant cell has a cell wall and chloroplast, while the animal cell lacks both of them. Thus, option B is correct.
The cell has been the smallest unit of life that has been performing varying functions with the help of different organelles.
The plant cell has been exposed to harsh environmental conditions, thus has been consisting of the cell wall along with the cell membrane. However, animal cell lacks a cell wall.
The food has been processed in the plant cells with the help of photosynthesis that required chlorophyll. The chlorophyll has been consisted in the chloroplast. Thus plants cell have consisted of chloroplast, however, animal cells lack chlorophyll as well as chloroplasts.
Thus, the plant cell has a cell wall and chloroplast, while the animal cell lacks both of them. Thus, option B is correct.
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i need so much help 50 points!!!!!! complete the graph
Is nuclear energy poised to be part of America’s future?
Answer:
Nuclear energy powers our businesses, homes and military. America’s 95 operating nuclear reactors generate approximately 20% of our nation’s electricity and provide over half of our carbon-free energy. They also create good-paying jobs at power plants and uranium mines. Wyoming produced 87% of America’s domestic uranium supply in 2018.
Today, nuclear energy faces serious hurdles. Regulatory costs and subsidies for renewable energy technologies are forcing America’s nuclear power plants to close at an alarming rate.
Russia and China are subsidizing their government-owned nuclear companies to assert their energy influence around the world. China is searching the globe for uranium reserves and investing heavily in the countries where it’s found. They want to secure more nuclear fuel for themselves and increase their control of the global supply.
Meanwhile, American nuclear power plants have come to rely on cheap Russian imports of uranium to meet their nuclear fuel needs. Right now, roughly 40% of the uranium coming into the United States originates in Russia or its satellite states of Kazakhstan and Uzbekistan. Russian-backed companies are developing fuel that can be placed directly in American reactors.
Explanation:
how does skin protect the body from pathogens?
Answer:
It blocks pathogens from getting inside our body.
Explanation:
The skin is the biggest organ, it cover the whole body and organ system from any toxic things.
27. Based on Reference Table S, which of the
following atoms requires the least energy for the
removal of the most loosely bound electron?
A) Br
B) Sr
C) Be
D) Sn
Answer:
This question is incomplete but the correct option is B
Explanation:
This question is incomplete because of the absence of the "Reference Table S", however the question can still be answered in the absence of the table. The energy described in the question is the ionization energy (energy required to remove the most loosely bound electron in an atom). This question seeks to know the atom (from the options provided) with the least ionization energy.
Ionization energy increases from left to right across the period because it's easier to remove a single electron (valence electron) from the outermost shell than to remove two electrons from the same shell; thus the more the valence electrons (in a shell), the higher the ionization energy. Thus, bromine (Br) and tin (Sn) have high ionization energies because they have more number of electrons in there outermost shell.
Berylium (Be) and strontium (Sr) are both in the group 2 of the periodic table because they both have 2 electrons in there outermost shell. Ionization energy decreases down a group. This is because the farther an electron is from the nucleus, the weaker the force of attraction between the nucleus and the electron. Thus, strontium (Sr) would have a lesser ionization energy between the two and would indeed have the least ionization among the options provided. Hence, the correct option is B
What was J.J. Thomson's Model known as?
A. The Pizza Model
B. The Chocolate Chip Model
C. The Mint Chocolate Chip Model
D. The Butterscotch Model
Answer:
B.The Chocolate Chip Model
Explanation:
PLEASE HELP ASAP!!
What is the purpose of a unit conversion?
O
A. To change an amount in one unit to its equivalent amount in
another unit
B. To express a scientific expression in a general form all scientists
can understand
C. To express the amount of something in terms of its number of
smallest units
D. To keep track of the units associated with a number throughout an
equation
Answer:
A
Explanation:
A conversion factor is used to change the units of a measured quantity without changing its value.
Unit conversion is very important because the rest of the world other than three contries uses the metric system. So, converting unitsis important in science because it uses the metric system. The metric system are measurements like cm, m, l, mL, etc.
NaOH
+
AL-
Na3AlO3 +
H2
How many moles of NaOH are required to produce 405 moles of hydrogen?
Answer:
i have no idea and i dont get it
How many molecules are present in 3HNO4?
1) 14
2) 18
3) 3
4) 4
Answer:
2
Explanation:
If you take H and N, that is two molecules right off the bat. If you take O4, that makes 6. Take the total of all 6, and multiply it by 3, with equals 18.
3HNO4 = 18
what properties of gold and platinum make these metals desirable for jewelry?
Answer: They are non-reactive and don't conform with other elements to form compounds. Because they are non-reactive, they don't corrode easily.
Explanation:
The properties of gold and platinum which make these metals desirable for jewelry is due to their electronic configuration due to which they are non-reactive and do not corrode easily.
What is electronic configuration?Electronic configuration is defined as the distribution of electrons which are present in an atom or molecule in atomic or molecular orbitals.It describes how each electron moves independently in an orbital.
Knowledge of electronic configuration is necessary for understanding the structure of periodic table.It helps in understanding the chemical properties of elements.
Elements undergo chemical reactions in order to achieve stability. Main group elements obey the octet rule in their electronic configuration while the transition elements follow the 18 electron rule. Noble elements have valence shell complete in ground state and hence are said to be stable.
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Which of the following is the correct electron dot structure for a hydroxide ion?
Answer:
A
Explanation:
A hydroxide ion is given as:
OH⁻
The electron dot notation shows only the chemical symbol of the element surrounded by dots to represent the valence electrons. The chemical symbol denotes the nucleus and all electrons except the valence electrons.
The dots are arranged on the four sides in pairs.
Oxygen is made up of 6 valence electrons, and since the ion has a net negative charge, the hydrogen and oxygen achieved their stable configuration this way.
Calculate the speed of a bicycle
traveling 20 km in 2 hours. Show the
formula, and your work with the correct
units. HELP PLEASE AND HURRY
Answer:
10 km/hr
............
The speed of a bicycle is 10 km/hour or 0.27 m/sec.
What is the Speed?The speed may be defined as the rate of change of position of an object in any direction. It is significantly measured as the ratio of distance to the time in which the distance was covered. Speed is a type of scalar quantity that has only direction but no magnitude.
According to the question, the distance traveled by bicycle = 20 km or 2000 meters.
The total time is taken = 2 hours or 7200 seconds.
Now, the formula for calculating the speed is as follows:
S = Distance/ Time = 20km/2 hours = 10 km/hour.
S = Distance/ Time = 2000 meters/7200 seconds = 0.277 m/sec.
Therefore, the speed of a bicycle is 10 km/hour or 0.27 m/sec.
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lonic bonds tend to form between
a. nonmetals; nonmetals
b. metals; nonmetals
c. metals; metals
d. all of these
How many valence electrons does this atom have? (Urgent plz help)
Answer: theres 5
Explanation: valence electrons are the electrons in the outer shell. I took that test a few weeks ago :0
Ca(C2H302)2
Name the following compounds.
Answer:
nut
Explanation:
What is the formula to the covalent molecule Hexaboron Diphosphide?
Answer:Naming Covalent compounds
A B
hexaboron silicide B6Si
chlorine dioxide ClO2
hydrogen iodide HI
iodine pentafluoride IF5
Explanation:
which of these is an equation that follows the law of conservation of mass
Answer:
D
Explanation:
The yield ( → ) symbol always points to the
I dont get what the question is?? im so sorry!
How many atoms of S are in the following formula: 3Na(SO4)2
1) 6
2) 8
3) 3
4) 5
Answer:
6
Explanation:
You witnessed a student throw away a broken beaker in the regular trash can. Which of the following is the most important reason to alert your instructor?
Answer:
D
Explanation: