Answer:
They work by increasing activity in the brain, particularly in areas that help control attention and behaviour. Methylphenidate is used to treat children with attention deficit hyperactivity disorder (ADHD). It helps with hyperactivity and impulsive behaviour, and allows them to concentrate better.
Explanation:
Methanol has a normal boiling point of 64.6C and a heat of vaporization of 35.2 kJ/mol. What is the vapor pressure (in Torr) of methanol at 12.0C
Answer:
vapor pressure of methanol at 12.0C = 75.09 torr
Explanation:
Using Clausius Clapeyron equation
, we have that
ln (P2/P1)= (ΔHvap /R) (1/T1 - 1/T2)
Given
At Normal boiling point,
Temperature T1= 64.6°C = 64.6 + 273 = 337.6 K, Pressure,P1 = 1 atm
Heat of vaporization = 35.2 kJ/mol
Changing to J/mol
=35.2 x 1000= 35200 J/mol
Temperature , T2 = 12.0oC = 12 + 273 = 285 K
Using gas constant, R = 8.314 J/mol.K
ln (P2/P1)= -(ΔHvap /R) (1/T1 - 1/T2)
ln (P2/ 1 atm) = (35200 J/mol/ (8.314 J/mol.K) X( 1/337.6 - 1/285)
ln (P2/ 1 atm) =4,233.822 X (0.00296-0.003508)
ln (P2/ 1 atm) = 4,233.822468 x-0.0005466866
ln (P2/ 1 atm)= -2.31457
P2 = e^⁻2.31457 x 1 atm
P2=0.098808atm
= 0.098808atm x760 = 75.09 torr
How can you increase the gravitational potential energy (GPE) of an empty shoe box on the middle shelf of a bookcase?
Answer:
Add Items to it
Explanation:
Lol I took the test. Sorry If I'm incorrect
Answer:
add items to the box to increase its mass on the self it is on
Explanation: :p
How many atoms are there in 4500 grams of sulfur(s)?plaease help
Answer: The Avagadro constant = 6.022 x 10²³ denotes the no of molecules in one mole of the substance
Explanation:
According to the theory of plate tectonics, where do activities such as earthquakes and volcanic eruptions occur?
A
along plate boundaries
B
in the centers of plates
C
above the surfaces of plates
D
in the outer regions of plates
Answer:
A or C.... Any one. If i am wrong let me know!
3. A student mixes a solid powder into a beaker of fluid. Which of the following would indicate that a chemical change has definitely occurred?
Explanation:
A chemical change is a change in which a new kind of substance is produced. Such changes are always accompanied by energy changes.
They are mostly reversible.
Some examples of such reactions are combustion, rusting of iron, precipitation, rancidity of butter, souring of milk.
There might be some little change in mass It requires a considerable amount of energyWhich of the following are products of the reaction listed? Zn + 2HCI
ZnCl2 + H2
H2
HCI
ZnCl2
Zn
Answer:
uh A.)? [ZnCI2+H2]? /////////
Explain why hydrogen can only have 2 valence electrons around it when it bonds to other items. What is the maximum number of bonds hydrogen will form?
Answer:
In first shell only 2 electrons are present in hydrogen only one electron is present in valence shell. To complete its duplet hydrogen can share lose or gain only one electron to form chemical bond.
Hydrogen can form only one bond.
Explanation:
Which of the following statements is true?
a. Atechnological society has no impact on the environment.
b. Atechnological society has a completely positive impact on the environment.
C. Atechnological society has both a positive and negative impact on the environment
d. Atechnological society has a completely negative impact on the environment.
Please select the best answer
Answer:
C. A technological society has both a positive and negative impact on the environment
Explanation:
It is correct to suggest and to acclaim that a technological society has both a positive and negative impact on the environment.
The environment is the region of space where living organisms and non-living components can be found.
Technology no doubt has opened up our knowledge about the environment. We are now aware of very topical issues that affects the environment and how to combat them. On the other side, technological advance has also bode poorly for the environment. New chemical wastes generated by industrial processes have proven very costly to the environment.We see that technology has both negative and positive effects on the environment.
In a typical calorimetry experiment (similar to what you did with the combustion of cheese balls), a small bag of Skittles (10.0 g) was combusted and the temperature of the water (1.00 kg) increased by 40.0 oC. How much energy (in calories and Food calories) was released by the combustion of the Skittles
This question is incomplete, the complete question is;
In a typical calorimetry experiment (similar to what you did with the combustion of cheese balls), a small bag of Skittles (10.0 g) was combusted and the temperature of the water (1.00 kg) increased by 40.0 °C.
a) How much energy (in calories and Food calories) was released by the combustion of the Skittles
b) How many small bags of skittles would a 140 lb person have to eat in order to equal the amount of food calories burned by walking a marathon?
Marathon = 26.2 miles, average person burns 0.453 food calories/mile pound)
Answer:
a)
Number of calories = 40000 Cal
Number of food calorie = 40 KCal
b)
41.54 bags of skittles are required
Explanation:
Given that;
mass of water = 1kg = 1000g
change in Temp ΔT = 40°C
specific heat of H₂O = 4.84 = 1 Cal
Now
heat absorbed by the water = MSΔT
= 1000gm × 1 cal × 40°C = 40000 Cal
so
Number of calories = 40000 Cal
(since food calories = 1000 small calories)
so
Number of food calorie = 40 KCal
Next
number of mile lb , if the man runs in the marathon will be;
26.2 × 140
= 3668 mile lb
0.453 food calorie is burned for 1 mile pound.
So, amount of food calorie required if the man runs in the marathon will be
0.435 × 3668 mile lb
= 1661.60 food calires.
now
40KCal food calorie is released by 10gm.
So, 1661.60 cal will be released from
⇒ (10gm × 1661.60) / 40 = 415.4 gm
now
1 bag = 10gm,
therefore 415.4 gm = 41.54 bags
∴ 41.54 bags of skittles are required
How many moles are present in 300.0 mL of acetone, given that the specific gravity of acetone is 0.784.
The number of moles of acetone is 4.1 moles.
What is the number of moles of acetone?Let us recall that specific gravity refers to the ratio of the density of a substance to the density of water. Also noting that the density of water has been set to 1 g/mL, the density of the acetone solution is 0.784 g/mL.
Density = mass/volume
mass = Density * volume
mass = 0.784 g/mL * 300.0 mL
= 235.2 g
Number of moles = mass/molar mass
Molar mass of acetone = 58 g/mol
Number of moles of acetone = 235.2 g/ 58 g/mol
= 4.1 moles
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An alkane with 15 carbons must contain how many hydrogens?
34
32
30
Answer:
It should contain 32 hydrogen.
Calculate the frequency of a beam of light that is 35.6m long.
Answer:
f = 0.084 s⁻¹
Explanation:
Given data:
Frequency of light = ?
Wavelength = 35.6 m
Solution:
Formula:
Speed of light = wavelength × frequency
Speed of light = 3× 10⁸ m/s
by putting values,
3× 10⁸ m/s = 35.6 m × f
f = 3× 10⁸ m/s / 35.6 m
f = 0.084 s⁻¹
Which of the following is NOT a level of organization in an ecosystem? a. community c. population b. ecosystem d. all of the above are levels of organization
Answer:
d. all of the above are levels of organization
Explanation:
The followings are the levels of the organization in an ecosystem
1. Individual
2. Population
3. Community
4. Ecosystem
5. Biome
6. Biosphere
So as per the given situation, it involved all three levels that are mentioned in the question
hence, the correct option is d.
Therefore the same is to be considered
The given option are all consisting in the level of organization of ecosystem. Thus, option D is correct.
The ecosystem has been the geographical representation comprising plants, animals, and other biotic and abiotic components.
The ecosystem has been organized in the levels for the understanding of the working and the activity of the ecosystem. The levels of the ecosystem has been:
IndividualPopulationCommunityEcosystemBiomeBiosphereThe organizational levels of the ecosystem have been comprised of community, population, and ecosystem. Thus all the given are level or organizations in the question. Thus, option D is correct.
For more information about the ecosystem, refer to the link:
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In the free radical chlorination of methylcyclopentane, what is the total number of distinct monochlorinated compounds, including stereoisomers, that would be formed?
A) 4
B) 6
C) 8
D) 10
Answer:
B) 6
Explanation:
Methylcyclopentane consist of 3 types of hydrogen which are 1° (primary), 2° (secondary) and 3° (tertiary) hydrogen atoms. In the chlorination of methylcyclopentane, there are four monochlorinated products possible and two stereoisomers.
Need help please....
Which two factors often determine the type of rock that is formed by a process?
A.The type of material that is present at the beginning of the process
B.The amount of time the process of rock formation takes
C.The season in which the rock formation process ends
D.Whether the process takes place north or south of the equator
Answer:
A and B
Explanation:
Trust me I just did it on a p e x
Answer: he’s correct it’s d and b for me but it’s the same answers
Explanation:
Calculate the wavelength of a radio wave with a frequency of 102.7 x 10^6 s^-1
Determine the frequency of light whose wavelength is 5.267 nm.
Answer:
λ = 0.029×10² m
f = 0.57×10¹⁷ s⁻¹
Explanation:
Given data:
Wavelength of wave = ?
Frequency of wave = 102.7×10⁶ s⁻¹
Solution:
Formula:
Speed of wave = Wavelength × Frequency
speed of wave = 3×10⁸ m/s
by putting values,
3×10⁸ m/s = λ × 102.7×10⁶ s⁻¹
λ = 3×10⁸ m/s / 102.7×10⁶ s⁻¹
λ = 0.029×10² m
2nd)
Given data:
Wavelength of wave = 5.267 nm (5.267×10⁻⁹ m)
Frequency of wave = ?
Solution:
Formula:
Speed of wave = Wavelength × Frequency
speed of wave = 3×10⁸ m/s
by putting values,
3×10⁸ m/s = 5.267×10⁻⁹ m × f
f = 3×10⁸ m/s / 5.267×10⁻⁹ m
f = 0.57×10¹⁷ s⁻¹
The jars below, from left to right, each contain exactly one mole of carbon, sulfur, and aluminum, respectively. Which jar contains the most atoms?
Answer:
D. Each jar contains the same number of atoms
Explanation:
Each of jar containing 1 mole of the element has consisted of an equal number of atoms.
Each jar has been consisted of 1 mole of gas. The number of atoms in a mole of gas can be calculated with Avogadro's number.
Avogadro number has been the constant, that relates the particles and the sample constituents. The value of the Avogadro number has been [tex]\rm 6.023\;\times\;10^2^3[/tex] .
1 mole of gas = Avogadro's number molecules
1 mole of Carbon = [tex]\rm 6.023\;\times\;10^2^3[/tex] atoms of carbon1 mole of Sulfur = [tex]\rm 6.023\;\times\;10^2^3[/tex] atoms of sulfur1 mole of Aluminum = [tex]\rm 6.023\;\times\;10^2^3[/tex] atoms of aluminum.Thus, each of them containing 1 mole of the element has consisted of an equal number of atoms.
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What are the respective concentrations (M) of Mg2+and Cl-afforded by dissolving 0.325 mol MgCl2 in water and diluting to 250 mL?A) 0.0013 and 0.0013B) 0.0013 and 0.0026C) 1.30 and.1.30D) 1.30 and 2.60E) 2.60 and 2.60
Answer: D) 1.30 and 2.60
Explanation:
Molarity of a solution is defined as the number of moles of solute dissolved per liter of the solution.
[tex]Molarity=\frac{n\times 1000}{V_s}[/tex]
where,
n = moles of solute
[tex]V_s[/tex] = volume of solution in ml
molarity of [tex]MgCl_2[/tex] = [tex]\frac{0.325\times 1000}{250ml}=1.30 M[/tex]
[tex]MgCl_2\rightarrow Mg^{2+}+Cl^{-}[/tex]
As 1 mole of [tex]MgCl_2[/tex] dissociates to give one mole of [tex]Mg^{2+}[/tex] and two moles of [tex]Cl^-[/tex] ions .
Molarity of [tex]Mg^{2+}[/tex] = 1.30 M
Molarity of [tex]Cl^{-}[/tex] = [tex]1.3 M\times 2=2.60M[/tex]
What is the Systematic name for the compound SECI2
Answer: selenium dichloride
Explanation:
REG: ED 101/6/12062
Course Code:
.
1. Using appropriate chemical equations, explain stellav nucleosynthe
sis of elements; o Ne, Na and Mg ( 6 Marks).
Answer:
See explanation
Explanation:
Nucleosynthesis is the process that creates new atomic nuclei from pre-existing ones via nuclear reactions.
A nuclear reaction involves the nucleus of atoms. It means the transformation of one element to another.
In the image attached i have shown the equations representing the nucleosynthesis of O, Ne, Na and Mg.
The nucleosynthesis of O involves the bombardment of C-12 with alpha particles, gamma rays are produced.
The nucleosynthesis of Ne involves the bombardment of O-16 with alpha particles, gamma rays are produced.
The nucleosynthesis of Na involves the bombardment of Ne-20 with alpha particles, protons are produced.
The nucleosynthesis of Mg involves the bombardment of Ne-20 with alpha particles, gamma rays are produced.
I need help plz before 12:18 because my teacher did she was going to Fall me
Answer:
You are right, it is the Engineer
Explanation:
454 grams of isomaltitol, C12H24O11, was combusted in a furnace completely in an excess oxygen. The products of this reaction are water and carbon dioxide. What is the theoretical yield (in kilograms) of water produced from this reaction?
The theoretical yield (in kilograms) of water produced from this reaction : 0.285 kg
Further explanationReaction
2C₁₂H₂₄O₁₁ + 25O₂ → 24CO₂ + 24H₂O
mass of C₁₂H₂₄O₁₁ - isomaltitol = 454 g
mol C₁₂H₂₄O₁₁(MW=344.31 g/mol) :
[tex]\tt mol=\dfrac{mass}{MW}\\\\mol=\dfrac{454}{344.31 g/mol}\\\\mol=1.319[/tex]
mol H₂O based on C₁₂H₂₄O₁₁ as limiting reactant(O₂-oxygen as an excess)
From the equation above, mol ratio of C₁₂H₂₄O₁₁ : H₂O = 2 : 24, so mol H₂O:
[tex]\tt mol~H_2O=\dfrac{24}{2}\times 1.319=15.828[/tex]
then mass H₂O (MW=18 g/mol) :
[tex]\tt mass=mol\times MW\\\\mass=15.828\times 18=284.904~g=0.285~kg[/tex]
What is the mass of a single bromine molecule, Br2?
The mass of a single bromine molecule, Br₂ is 2.654 x 10⁻²² g.
Bromine is a diatomic element. It has a symbol Br and the atomic number is 35. Bromine is a naturally occurring element which is liquid at room temperature.
Molar mass of Br₂ is 159.808 g/mol. The molar mass of bromine is 79.904 g/mol. In Br₂, there are two bromine atoms.
To calculate the mass of a single bromine molecule -
In 1 mole of Br₂, there is Avogadro's number of molecules.
Avogadro's number = 6.022 x 10²³
Therefore, 1 mole = 6.022 x 10²³
1 mole of bromine has mass of 79.9 g/mol
So, it gives us -
1/6.022 x 10²³ = 1.66 x 10²³/79.9 = 2.654 x 10⁻²²g
For the mass of a single bromine molecule, Br₂ = 2.654 x 10⁻²² g
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Two identical sister chromatids are held together at what
region on a duplicated chromosome?
a Chromatin
b Centromere
C Centriole
Check it
If I DECREASE the mass and INCREASE the distance, what happens to the force of gravity?
Answer:
Decreases
Explanation:
F = GM1M2/R²
please mark me brainliest and 5 star
20. Rank the following elements from the smallest to largest ionization energy:
a. Sulfur, Oxygen, Polonium, Selenium
Answer:
Polonium
Selenium
Sulfur
Oxygen
Explanation:
If you see in the Table S of the periodic Table there is a column that says First Ionization Energy (kJ/mol) and you can see the numbersof these elements so then you just put it in order
Polonium 812
Selenium 941
Sulfur 1000
Oxygen 1314
5. What is the distance of something from side to side?
Answer:
Distance of something it can be any type of distance
Determine the overall orders of the reactions to which the following rate laws apply:
(a) Rate = K[NO2]
(b) Rate = K[H2][Br2]^1/2
(c) Rate = K
Answer:
How do you determine the overall order of a reaction?
The overall order of the reaction is found by adding up the individual orders. For example, if the reaction is first order with respect to both A and B (a = 1 and b = 1), the overall order is 2. We call this an overall second order reaction.
Explanation:
QUESTION 7
5 points
Save Answer
If you know that ethylene glycol liquid (antifreeze) has a density of 1.113 g/ml, please calculate how much 39.5 cc's of ethylene glycol weighs?