Which of the following elements have the highest percentage in terms of frequency in the Earth's crust and human body, respectively? A. Nitrogen, Oxygen. B. Oxygen, Silicone. C. Carbon, Oxygen. D. Oxygen, Oxygen
Answer:
Oxygen is the most abundant element in the Earth's crust.
Explaination: It makes up 46% of the mass of the Earths crust.
Answer
The most abundant elements in the human body are oxygen, carbon and hydrogen. Oxygen makes up 65% of the body.
What is the molarity of 1. 5 liters of an aqueous solution that contains 52 grams of lithium fluoride.
Answer:
1.3 M
Explanation:
The formula mass of lithium fluoride is 7+19=26 g/mol. This means that in 52 grams of LiF, there is 2 moles.
Molarity = (moles of solute)/(liters of solution), so the answer is 2/1.5 = 1.3 M
calculate the moles of 70g of Li
[tex]\text{No. of moles} = \dfrac{\text{Mass of substance(Li)}}{\text{Molar mass of of substance(Li)}}\\\\\\~~~~~~~~~~~~~~~~~=\dfrac{70}{6.94}\\\\\\~~~~~~~~~~~~~~~~~=10.08~ \text{mol.}[/tex]
A hydrogen atom initially in its ground state absorbs a photon with a wavelength of 97.25 nm. To which energy level is it excited
This question involves the concept of excitation energy.
The energy level to which the atom is excited is "4".
What is excitation energy?The excitation energy of an atom is defined as the energy required by the atom to get excited from one energy level to some upper energy level. Mathematically, it can be given by the following formula:
[tex]E=E_o(\frac{1}{n_i^2}-\frac{1}{n_f^2})[/tex]
where,
E = excitation energy = [tex]\frac{hc}{\lambda} = \frac{(6.63\ x\ 10^{-34}\ J.s)(3\ x\ 10^8\ m/s)}{9.725\ x\ 10^{-8}\ m}=2.04\ x\ 10^{-18}\ J[/tex]
E (in eV) = [tex](2.04\ x\ 10^{-18}\ J)(\frac{1\ eV}{1.6\ x\ 10^{-19}\ J})[/tex] = 12.78 eV
h = plank's constant = 6.63 x 10⁻³⁴ J>s
c = speed of light = 3 x 10⁸ m/s
λ = wavelength = 97.25 nm = 9.725 x 10⁻⁸ m
E₀ = energy of hydrogen atom in ground state = 13.6 eV
[tex]n_i[/tex] = initial orbit = 1
[tex]n_f[/tex] = final orbit = ?
Therefore,
[tex]12.78\ eV=13.6\ eV(\frac{1}{1^2}-\frac{1}{n_f^2})\\\\\frac{12.78\ eV}{13.6\ eV}=1-\frac{1}{n_f^2}\\\\\frac{1}{n_f^2}=1-0.94\\\\n_f^2=\frac{1}{0.06}\\\\n_f=\sqrt{16.67}\\n_f = 4[/tex]
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1-3 gas stoichiometry! please help and put in steps in every problem. please help if u can
Answer:
um Im not sure what the heck that is
What kind of music might you expect from a group that called themselves "The Entropics"?
Answer:
See explanation.
Explanation:
Heavy metal or something else that is heavily disordered. Would still sound better than cardi b.
what is an example of taking action or doing service in the cement industry
Answer:
mining of clay limestone and then heated to a certain temperature of 1450⁰ in a cement kiln
Choose all that apply for raft spiders.
question 9 options:
raft spider's legs have a waxy surface that repels water
raft spiders sprint along submerged plants to catch underwater prey.
raft spider's light weight and large surface area allow it to walk on water.
raft spider's heavy weight and small surface area allow it to walk on water
Raft spider's light weight and large surface area allow it to walk on water.
What are raft spiders?Raft spiders are a specie of siders that can move on the surface of water. They are found around the north-western and central Europe.
The following apply to the raft spiders;
raft spider's legs have a waxy surface that repels waterraft spider's light weight and large surface area allow it to walk on water.Learn more about raft spiders:https://brainly.com/question/11416236?
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Guided Practice
Old-fashioned windmills are not aerogenerators because
Answer:
What is the main problem with windmills?
Image result for Guided Practice Old-fashioned windmills are not aerogenerators because
As with all energy supply options, wind energy can have adverse environmental impacts, including the potential to reduce, fragment, or degrade habitat for wildlife, fish, and plants. Furthermore, spinning turbine blades can pose a threat to flying wildlife like birds and bats.
Why are the windmills not moving?
Why do the turbines not spin at times? The most common reason that turbines stop spinning is because the wind is not blowing fast enough. Most wind turbines need a sustained wind speed of 9 MPH or higher to operate. Technicians will also stop turbines to perform routine maintenance or repairs.
Calculate the energy required to produce 6.0 moles of Cl2O7 using the following reaction 2 Cl2 + 7 O2 + 130kcal -> 2 Cl207
Answer:
455 Kcal
Explanation:
2Cl2(g) + 7O2(g) + 130kcal → 2Cl2O7(g)
Rearranging we get,
2Cl2(g) + 7O2(g) → 2Cl2O7(g) Δ H = 130 kcal . mol⁻¹
So for per mol reaction will be as above.
In case of 7 mols of product, we need 7/2 mole ratio x 130 = 455 Kcal
For group 1a metals, which electron is the most difficult to remove?
The periodic table contains groups and periods that include the elements. For group 1 metal lithium is least likely to lose an electron.
What are group 1 metals?Group 1 metals are the alkali metals that include, Li, Na, K, Rb, and Cs. They show the property exhibited by the metals. The chemical trends of group 1 show that cesium loses an electron more easily than the other elements.
When going down the group the tendency to lose electrons increases as the atomic radius increases. The electron gets far away from the nucleus making it easy to get removed.
Therefore, lithium being the first element of the group has the smallest radii and is least likely to lose an electron.
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What is the mass number of an isotope with an atomic number of 57 and that has 69 neutrons?
Answer:
mass number=126
Explanation:
57+69=126
Sodium hydroxide (NaOH) is a strong base that is very corrosive. What is the mass of 2.75 × 10-4 moles of NaOH?
3.24 x 10–3 g NaOH
1.10 x 10–2 g NaOH
6.10 x 10–2 g NaOH
6.50 x 10–2 g NaOH
The mass of 2.75 × [tex]10^{-4}[/tex]moles NaOH will be 1.1 x [tex]10^{-2}[/tex] grams
Mass/mole relationshipRecall that:
Mole = mass/molar mass.
Thus, mass = mole x molar mass.
In this case, the mole is 2.75 × [tex]10^{-4}[/tex] moles and the molar mass of NaOH is 40 g/mol.
Mass = 2.75 × [tex]10^{-4}[/tex]x 40 = 1.1 x [tex]10^{-2}[/tex] grams
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Answer:
Answer is option B or:
1.10 x 10–2 g NaOH
Explanation:
hope this helps! (edge)
Antoine lavoisier is credited with the discovery of the law of conservation of mass. the law states that in a chemical reaction, matter is not created or destroyed but preserved. which equation correctly models this law?
h2 + cl2 ---> 2hcl
h2 + cl2 ---> hcl
h + cl ---> 2hcl
2h2 + cl2 ---> 2hcl2
The Antoine's law means that the amount of substance before reaction must be equal the amount of substance after reaction
The equation h2 + cl2 ---> 2hcl correctly models this law.
the condensed formula ch3ch(ch3)2 represents
The molecular formula CH₃CH(CH₃)₂ is the condensed formula for the hydrocarbon methylpropane.
What are organic compounds?Organic compounds are compounds that are obtained from organic materials.
The most common organic compound are the hydrocarbons,
The hydrocarbons includes the alkanes, alkenes, alkynes, etc.
The given compound CH₃CH(CH₃)₂ is the condensed formula for the hydrocarbon methylpropane.
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Why is science boring
Answer:
cuz what we are shown in school often fails to foster curiosity in us.
Explanation:
Explanation:
because it have many laws, theory, reaction and many more which is enough to make a student depressed
How does increased air temperatures affect salinity of the oceans and the great
ocean conveyor belt?
1. increased air temperatures decreases the salinity of the ocean since more ice is
melting adding more freshwater to the oceans, therefore slowing down the great
ocean conveyor belt.
2. increased air temperatures decreases the salinity of the ocean since more ice is
melting adding more freshwater to the oceans, therefore speeding up the great ocean
conveyor belt.
3. increased air temperatures increases the salinity of the ocean since more water is
evaporating into the atmosphere, therefore slowing down the great ocean conveyor
belt.
4. increased air temperatures increases the salinity of the ocean since more water is
evaporating into the atmosphere, therefore speeding up the great ocean conveyor
belt.
Increased air temperatures decrease the salinity of the ocean since more ice is melting adding more fresh water to the oceans, therefore slowing down the great ocean conveyor belt.
What is an ocean conveyor belt?Ocean conveyor belt system in which water moves between the cold depths and warm surface in oceans throughout the world.
Increases in temperatures of surrounding entities like ice and an increase in precipitation adds fresh water into the sea, which lower salinity. Seawater with lower salinity is lighter in density and won't sink as much as denser water.
As the seawater gets saltier, its density increases, and it starts to sink. Surface water is pulled in to replace the sinking water, which in turn eventually becomes cold and salty enough to sink. This initiates the deep-ocean currents driving the global conveyer belt.
Hence, option A is correct.
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In a room there is a 100g block of aluminum and a container holding 200g of liquid water. In one instant the aluminum is 10 °C and the water is at 1 °C. At that instant, which object has more thermal energy? Show your work.
Answer:
Explanation:
Givens
The heat capacity for aluminum = 0.89 J/(oC*grams)
The heat capacity for water = 4.18
m water = 200 grams
t water = 1 degree C
t aluminum = 10 degrees C
Formula
Thermal energy = m * c * t
Solution
Water
Energy = m * c * t
Energy = 200 * 4.18 * 1
Energy = 836 Joules
Aluminum
Energy = mc t
Energy =100 * 0.89 * 10
Energy = 890
Answer Aluminum has the higher Thermal Energy
Note this is a very tricky question. Usually delta t is given in terms of a change in temperature or heat transfer. This question assumes the substance is at a constant temperature at a short time interval so delta t is a constant amount for that time interval. Be very careful when you think about this, because the laws of thermo dynamics begin to act almost immediately.
When trying to identify an unknown element a scientist determines
Elements are a substance that is the smallest unit and can't be divided further. The number of valence electrons determines the reactivity with other elements.
What are valence electrons?Valence electrons are the electrons that are found in the outermost shell of the atom. These electrons take part in chemical reactions to form chemical bonds.
The number of these electrons will help determine how the unknown element reacts with the other elements chemically as valence electrons are responsible for the chemical bond formation.
Therefore, the valence electrons of the unknown element are used to determine the property.
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Need help with this chemistry question will reward with 50 points just please put the correct answer I'm very confused on it
Answer: 2Na3 (s)-> 2Na (s) +3N2 (g)
Explanation:
look at the keywords then balance equation
Ionization, radical and valency electron
Answer:
Ionization, in chemistry and physics, any process by which electrically neutral atoms or molecules are converted to electrically charged atoms or molecules (ions).radical, also called Free Radical, in chemistry, molecule that contains at least one unpaired electron. For neutral atoms, the number of valence electrons is equal to the atom's main group number.What is the chemical formula of polypropylene (in text, no pictures)?
Answer:
(C3H6)n
it is made up of carbon and hydrogen atoms.
Wave particle duality is most apparent in analyzing the motion of.
Answer:
Wave particle duality is most apparent in analyzing the motion of. an electron. A photon of which electromagnetic radiation has the most energy.
Wave particle duality is most apparent in analyzing the motion of an electron.
What is wave-particle duality used for?Wave-Particle duality used to realize the particle and wave nature of light. Based on the idea that light and all other electromagnetic radiation may be considered a particle or a wave nature, in 1923 physicists Louis De Broglie suggested that the same kind of duality must hold to matter.
For example, an electron that produced part of an electric current in a circuit behaves like a particle moving in unison with other electrons inside the conductor. The same electron acts as a wave when it passes over through with a solid crystalline structure and forms a diffraction image.
A photon of which electromagnetic radiation has the most energy.
Thus, Wave particle duality is most apparent in analyzing the motion of. an electron.
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How many grams of glucose would be found in 1l of a 22% solution?
40 g glucose
Explanation:
I have to assume that you are asking about a 2% m/v solution ( Note that specifying 2% in isolation has no meaning )
2% m/v glucose solution is : 2 g glucose in 100 mL solution
Which is ( multiply by 10): 2% m/v = 20 g glucose in 1000 mL ( = 1.0 L) solution
And so 2%m/v = 40 g glucose in 2000 mL or 2.0 L solution
Answer: 40 g glucose.
Can someone please help? This is super hard!!
Organic Compounds are named according to IUPAC Nomenclature technique.
The name for the first structure is 3-Bromo-2,4-dimethylhexane.
"International Union of Pure and Applied Chemistry "
Following are the names of given structures ;
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How much mass would a sample of magnetite, a magnetic stone, with a volume of 8 cm^3 and a density of 5 g/cm^3 have?
According to the law of definite proportions, if a sample of a compound contains 24.00 grams of carbon and 4.00 grams of hydrogen, then another sample of the same compound which contains 48.00 grams of carbon must contain ________. Group of answer choices
Answer: 8.00 grams
Explanation:
The ratio of carbon and hydrogen must be the same.
Which statement is true about A nickel-cadmium dry cell?
Answer:
The cathode reaction is NiO2+H2O+2e−→Ni(OH)2+2OH−.
A gas has a volume of 62.65 L at STP. At what temperature (in oC) would the volume of the gas be 78.31 L at a pressure of 612.0 mm Hg?
Answer:
1.788 C DEGREES
Explanation:
STP is 1 atm at 273.15 K
P1V1/T1 = P2V2/T2
(1)(62.65) / (273.15) = (612/760)(78.31)/T2
T2 = 274.93 K = 1.788 C
what is the different nobel gases that didnt have octet rule
The noble gas, Helium has only two electrons with the electronic configuration as 1s2. Hence, it does not have a complete octet. and thus, it doesn't follow the octet rule.
An octet is a set of eight. Atoms of each of the noble gases (except helium) have eight electrons in their highest occupied energy levels and the general electron configuration of ns2np6.