The energy of an electron at n=2 is determined as -3.4 eV.
What is energy level an electron?The energy level of an electron is the fixed distances from the nucleus of an atom where electrons may be found.
Energy of an electron at a known energy levelThe energy of an electron at a known energy level can be calculated using the following formula as shown below.
En = -13.6/n²
where;
n is the energy level of the electronSubstitute the given parameters and solve for the energy of the electron at the given energy level.
En = (-13.6)/(2²)
En = -3.4 eV
Thus, the energy of an electron at n=2 is determined as -3.4 eV.
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Which element, Oxygen (O) or Fluorine (F), has a smaller atomic radius?
O, because the attraction between protons and valence electrons is weaker.
F, because the attraction between protons and valence electrons is stronger.
F, because the attraction between protons and valence electrons is weaker.
O, because the attraction between protons and valence electrons is stronger.
Fluorine has a smaller ionic radius than oxygen, because the attraction between protons and valence electrons is stronger; option B
What is ionic radius?Ionic radius is the radius of an ion of an element given by the distance from the nucleus up to where the nucleus has an influence on the ion's electron cloud.
The ionic radius of ions of elements depends on;
the nuclear charge, electron shielding,the number of electron shells as well as the number of electrons in the outermost shell of of an ion of an element.The greater the nuclear charge, the smaller the ionic radius.
The greater the electron shielding effect, the greater the ionic radius.
For non-metallic ions just as in metallic ions, the ionic radius decreases from left to right across the period table as a result of the increase in the nuclear charge of the ions.
Also, the ionic radius of nonmetals increase on going down the same group in the periodic table due to to increase in electron shielding as well as addition of an extra electron shell.
Therefore, the ionic radius of fluorine will be smaller than that of oxygen because of a greater nuclear charge.
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Name the following covalent compounds
The atoms of covalent compounds are connected by covalent bonds. Sharing one or more pairs of valence electrons results in the formation of a covalent bond.
How to name covalent compound-
1. Give the elemental name of the non-metal that is on the periodic table that is farthest to the left.
2. Give the other non-metal's name and a suffix ending, such as -ide.
3. To denote the quantity of an element in a molecule, use the prefixes mono-, di-, tri-, etc.
4. Mono is understood and not written if it is the initial prefix.
Names of covalent compounds according to the question-
1. CO₂ - Carbon Dioxide
2. CO - Carbon Monoxide
3. N₂O₄ - Dinitrogen tetraoxide
4. PCl₃ - Phosphorus trichloride
5. CBr₄ - Tetra bromomethane
6. P₂O₅ - Phosphorus pentoxide
7. PCl₅ - Phosphorus pentachloride
8. NF₃ - Nitrogen Trifluoride
9. SO₂ - Sulfur dioxide
10. SO₃ - Sulfur trioxide
11. SCl₆ - sulfur hexachloride
12. SiCl₄ - Silicon tetrachloride
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Jalen's aunt is a meteorologist. She explains to him that, in order to understand the weather, it is important to understand how water moves from the surface of Earth to the atmosphere. If Jalen wants to learn more about the process that moves water in this way, what should he study?
Answer:
Studies have revealed that evaporation—the process by which water changes from a liquid to a gas—from oceans, seas, and other bodies of water (lakes, rivers, streams) provides nearly 90% of the moisture in our atmosphere. Most of the remaining 10% found in the atmosphere is released by plants through transpiration.
Explanation:
PLEASEE HELPPPPP
the law of conservation of mass states that mass cannot be created nor destroyed. Explain what this means and provide an example. Use details to support your answer.
What is meant that mass cannot be created nor destroyed in the law of conservation of mass is that, matter can take part in a chemical reaction, but the initial mass of the matter (reactants) will be equal to the final mass of the matter (products formed).
What is law of conservation of mass?
The law of conservation of mass states that the mass can neither be created nor destroyed but it can be transformed from one form to another.
Examples of law of conservation of mass;
when firewood burns, the mass of the soot, ashes, and gases equals the original mass of the charcoal and the oxygen when it first reacted.So, in the law of conservation of mass, the sum of the masses of the reactants in a chemical reaction and products formed in the process remains unchanged.
Thus, what is meant that mass cannot be created nor destroyed in the law of conservation of mass is that, matter can take part in a chemical reaction, but the initial mass of the matter (reactants) will be equal to the final mass of the matter (products formed).
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Answer:
The law of conservation of mass states that the mass can neither be created nor destroyed but it can be transformed from one form to another.
Explanation:
If you know that the heat lost by placing a warm piece of metal in cool water is 150 kJ, how much heat is gained by the water?
an isotopes of caesium-137 has a half-life of 30 years. if 1.0g of Cs-137 disintegrates over a period of 90 years, how many grams of Cs-137 would remain?
After 90 years amount of Cs-137 isotopes has a half-life of 30 years. would remain is equal to = 0.125 grams.
An important and useful factor of radioactive decay is half of life, which is the amount of time it takes for one half of a radioactive isotope to decay. The half of-life of a selected radioactive isotope is constant; it is unaffected by way of situations and is independent of the initial quantity of that isotope.
The half of life of a chemical reaction can be defined because the time is taken for the awareness of a given reactant to attain 50% of its preliminary awareness. The half of-life of a response is the time required for the reactant's attention to decrease to at least one-half of its initial price. The half of-life of a first-order response is consistent this is associated with the charge consistent for the reaction. t1/2 = 0.693/k
Since all radioactive reaction follows first-order reaction, The rate of reaction does not depend on initial concentration.
calculation:-
1 gram Cs-137 at T = 0
after the first half,
⇒0.5 gram Cs-137 at T = 30
After the second half,
⇒0.25 gram Cs-137 at T = 30.
After the third half,
⇒0.125 gram Cs-137 at T = 90 years.
Hence, after 90 years amount of Cs-137 would remain is equal to = 0.125 grams.
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What volume of silver will weigh exactly 2500g. The density of silver is 10g/cm3
Answer:
250 cm ^3
Explanation:
what's the structure of benzene ?
anyone willing to talk rn ?
Answer:
The structure has a six-carbon ring which is represented by a hexagon and it includes 3-double bonds.
How would you prepare 10mL of a 0.25% m/V HCI solution if 1% m/V HCI was available? How much 1% m/V HCI is needed? How much distilled water is used?
We need to add 7.5 mL of distilled water to the 1% m/V HCI solution available.
What is the volume needed?The percent concentration is one of the common units of concentration that could be used to describe the amount of substance. Let us now try to obtain the volume needed.
Given that;
C1V1=C2V2
C1 = initial concentration
V1 = Volume of the stock solution
C2 = final concentration
V2 = volume of the new solution
Thus;
V1 = C2V2/C1
V1 = 0.25 * 10/1
= 2.5 mL
Hence, the volume of distilled water needed = 10mL - 2.5 mL
= 7.5 mL
Thus, we need to add 7.5 mL of distilled water to the 1% m/V HCI solution available.
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Each dot represents an atom. Different colors represent different types of atoms. Match the picture with the correct type of substance it
represents.
column A
1.___ A
2.___ B
3.___C
4.___D
5.___E
6.___F
column B
a. mixture
b. element
c. compound
You measure a rectangular solid and find it to be 9.14 cm long, 3.82 cm wide, and 5.63 cm high. The mass
of the solid is 74.319g. Determine the density of the solid
The density of the rectangular solid is 0.378 g/ [tex]cm^3}[/tex] .
Density of rectangular solid is calculated by ratio of mass by volume of the of rectangular solid .
Density = mass / volume
mass = 74.319 g ( given )
length of the rectangular solid = 9.14 cm
wide of the rectangular solid = 3.82 cm
height of the rectangular solid = 5.63 cm
volume = length × width × height = 9.14 cm × 3.82 cm × 5.63 cm
volume = 196.57 [tex]cm^3}[/tex]
putting the value of mass and volume in equation ( i ) we get ,
Density = mass / volume
Density = 74.319 g / 196.57 [tex]cm^3}[/tex] = 0.378 g/ [tex]cm^3}[/tex]
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which of the following gives the best description of the speed
Answer:
40 km in a hour?
Explanation:
What are the products formed when an acid reacts with a metal carbonate?
Answer:
Carbon dioxide gasMetal saltWaterExplanation:
[tex]{ \rm{MCO_{3(s)} + HX _{(aq)} \: \rightarrow \: MX_{(s)} + CO _{2(g)} + H _{2}O _{(l)} }}[/tex]
- MCO_3; Can be any metal carbonate such as Magnesium carbonate, Aluminum carbonate.....
- HX; can be any acid such as sulphuric acid, hydrochloric acid, nitric acid.....
- MX; is a metal acidic salt such as magnesium sulphate from magnesium carbonate and sulphuric acid, Aluminum chloride from Aluminum carbonate and hydrochloric acid.
To tolerate biting forces that average 28,000 psi modern dental restorative materials have strengths in excess of
To tolerate biting forces that average 28,000 psi, modern dental restorative materials have strengths in excess of dna psi.
What is dna ?Deoxyribonucleic acid is a polymer made of two polynucleotide chains that coil around one another to form a double helix and which contains the genetic material necessary for the growth, development, and reproduction of all known organisms as well as a large number of viruses. The two types of nucleic acids are DNA and RNA. One of the four major types of macromolecules that are necessary for all known forms of life is nucleic acids, along with proteins, lipids, and complex carbohydrates (polysaccharides).
Due to the fact that the two DNA strands are made up of more straightforward monomeric units known as nucleotides, they are referred to as polynucleotides. Each nucleotide consists of a phosphate group, a sugar called deoxyribose, and one of the four nucleobases that contain nitrogen: cytosine (C), guanine (G), adenine (A), or thymine (T).
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Which sample will have the greatest mass?
Question 3 options:
a)2 mol NO
b) 2 mol NO2
c) 3 mol NO
d) 3 mol NO2
Answer:
C
Explanation:
C is the right answer for this question.
A metal (M) forms a compound with the formula MCl2 . The compound contains 57.69% Cl by mass. Identify the metal in the compound? Give the symbol of the metal.
A metal (M) forms a compound with formula MCl₂. The compound contains 57.69% Cl by mass and the metal is Chromium. Symbol of Chromium metal is Cr.
Given :
57.69 % Cl by mass means that 57.69 grams of chlorine present in 100 grams of compound.
Mass of compound = 100 g
Mass of chlorine = 57.69 g
Mass of metal = 100 - 57.69= 42.31 g
First, we will calculate the moles of chlorine, using formula
Moles = Given mass
molar mass
Moles = 57.69
35.45
Moles = 1.627 moles
The given formula of compound is, MCl₂
Therefore, ratio of M : Cl = 1 : 2
We will calculate the moles of metal,
2 moles of Cl combines with 1 mole of metal
1.627 mole of Cl combines with 1.627 = 0.813 mole of metal
2
calculate the molar mass of metal -
Molar mass of metal = Given mass
moles
Molar mass = 42.31 g = 52.04 g/mol
0.813 mol
The molar mass of metal is 52.04 g/mole.
From this, we can conclude that the metal is Chromium (Cr)
So, the formula will be, CrCl₂
Hence, the identity of the metal is Chromium (Cr)
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Which is the correct formula for copper(II) phosphate?
Answer:
Cu3(PO4)2
ExplanatiWhich of the following is a physical change?
A) Magnesium reduces dry ice, forming black
carbon and MgO.
B) Water forms hydrogen and oxygen gases
via electrolysis.
C) The pH of water is raised by dissolving
sodium hydroxide.
D) Ice forms as water is poured onto dry ice.
E) Water hydrates cobalt chloride, turning
it from blue to pink.
Ice forms as water is poured onto dry ice is a physical change .
So , option D is correct one .
The physical change is explained in following points ,
A physical change is one that simply affects the physical nature of the substance without changing their chemical properties .Its chemical properties remain unchanged .Usually, increasing the temperature or applying pressure—or both—will cause a physical change .Reversing the condition—lowering the temperature, the pressure, or both—restores the material's initial state .In other words, physical changes are reversible .to learn more about physical change please click here ,
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If your front lawn is 18.0 feet wide and 20.0 feet long, and each square foot of lawn accumulates 1450 new snowflakes every
minute, how much snow, in kilograms, accumulates on your lawn per hour? Assume an average snowflake has a mass of
1.60 mg.
The mass of the snow flakes that accumulates in one hour is 15552 Kg.
What is the mass of the snowflakes?We know that area is the product of the length and the breadth of the lawn. We have to first obtain the area of the lawn as;
Length = 20.0 feet
Width = 18.0 feet
Area = 20.0 feet * 18.0 feet = 360 square feet
If 1 square feet accumulates 450 new snowflakes every minute
360 square feet accumulates 360 square feet * 450 new snowflakes every minute/ 1 square feet
= 162000 new snowflakes every minute
If 162000 new snowflakes accumulates in one minute
x snow flakes accumulates in 60 minutes
x = 9720000new snowflakes
If 1 snow flake has a mass of 1.60 mg
9720000 new snowflakes has a mass of 9720000 snowflakes * 1.60mg/ 1 snow flake
= 15552000 mg or 15552 Kg
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At what temperature would 4.62 g of KCl begin to crystallize in 10 mL of water?
Answer:
7° it's that cause the crylatise
The temperature at which 4.62 g of KCl begins to crystallize in 10 mL of water is 62° Celsius.
What is temperature?Temperature is the measurement of the hotness or coldness of the body. It is denoted by Kelvin.
Given, m=4.62 g of KCl, V= 10 ml of water
ro = 1 g/ml for water, so m(water)
V x ro = 10ml x 1(g/ml) = 10 g.
Solubility (for water as solvent) is defined as grams of solute dissolved per 100g of water.
So solubility for this case = m(KCl)/m(water) =
4.62g of KCl/10g of water = 46.2 g of KCl/100 g of water.
According to the graph below, KCl's solubility reached 46.2 g/100 g at a temperature of about 62 degrees Celsius.
KCl/10 g of water or 46.2 g of KCl/100 g of water.
Therefore, cooling the solution is necessary for crystallization. Crystallization will occur in this situation as soon as the temperature falls below 62 degrees Celsius (about).
The ultimate conclusion is that this KCl solution in water will begin to crystallize at 62 degrees Celsius (about).
Therefore, the temperature is 62° Celsius.
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which substance can be broken down by a chemical change ?
1) magnesium
2) manganese
3) mercury
4) methanol
Answer:
Methanol
Explanation:
Methanol is a compound and compounds are pure substances formed by the combination of elements; they can be decomposed by ordinary chemical means. The other answers are incorrect because they are elements and elements consists of only one kind of atom and they cannot be broken down into a simpler type of matter by either physical or chemical means.
What are the products formed when an acid reacts with a metal carbonate?
calculate basicity of H3PO4
H₃PO₄ is a Phosphoric acid and its Basicity is 3.
The basicity of a molecule is determined by the number of acidic hydrogen atoms present. The quantity of acidic hydrogen atoms in a substance is what determines its basicity.
To become acidic, a hydrogen atom must establish a very strong electronegative bond with an oxygen or fluorine atom. H₃PO₄ is acidic because the hydrogen atoms are bonded to or united to three oxygen atoms as a result. H₃PO₄ thus has a basicity of 3. Due to the fact that H₃PO₄ has a basicity value of 3, it is a tribasic acid. The ability of a base to replace a number of hydrogen atoms in a certain acid is known as the basicity process. In H₃PO₄, there are three atoms therefore, the basicity is 3.
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(C3H8) What mass of carbon dioxide (in kg ) is produced upon the complete combustion of 40.2 L of propane (approximate contents of two 5-gallon tanks)? Assume that the density of the liquid propane in the tank is 0.621 g/mL . (Hint: Begin by writing a balanced equation for the combustion reaction.)
The mass of carbon dioxide is obtained as 236 g of carbon dioxide.
What mass of carbon dioxide is produced?We know that the first step when we are trying to solve any type of question that involves stoichiometry is that we have to obtain the balanced reaction equation. This would show us the kind of interaction that is able to take place in order to obtain the results that we seek.
The reaction equation is given as;
C 3 H 8 + 5 O 2 → 3 CO 2 + 4 H 2 O
If 1 mole of propane occupies 22.4 L
x mole of propane occupies 40.2 L
x = 1 mole * 40.2 L /22.4 L
x = 1.79 moles
Now;
1 mole of propane produced 3 moles of carbon dioxide
1.79 moles of propane produced 1.79 moles * 3 moles/1 mole
= 5.37 moles of carbon dioxide
Mass of carbon dioxide =5.37 moles * 44 g/mol = 236 g of carbon dioxide.
The mass of carbon dioxide is obtained as 236 g of carbon dioxide.
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1.) The severity of a tropical storm is related to the depressed atmospheric pressure at its center. In August 1985, Typhoon Odessa in the Pacific Ocean featured maximum winds of about 90 mi/hr and pressure that was 40.0 mbar lower at the center than normal atmospheric pressure. In contrast, the central pressure of Hurricane Andrew (pictured) was 90.0 mbar lower than its surroundings when it hit south Florida with winds as high as 165 mi/hr.
If a small weather balloon with a volume of 50.0 L at a pressure of 1.00 atmosphere was deployed at the edge of Typhoon Odessa, what was the volume of the balloon when it reached the center?
2.) A balloon is filled to a volume of 12.5L at a temperature of 27.1ºC. If the pressure in the balloon is measured to be 2.20 atm, how many moles of gas are contained inside the balloon?
The severity of a tropical storm is related to the depressed atmospheric pressure at its center, then the volume of the balloon is 4.164 L.
What is pressure?Pressure is defined as the force applied perpendicular to the surface of an object per unit area over which the force is distributed.
Volume is defined as the space occupied by the boundary of the object in 3D space.
For ideal gas the equation is P1V1 = P2V2
The pressure of center of Odessa storm is
P(in) = P(atm) - 40mbar = 1.0325 - 40.0 x 10⁻³bar = 0.97325 bar
On applying ideal gas equation
P(in)V(in) = P(out)V(out)
V(in) = P(out)V(out) / P(in)
= 1.01325 bar x 40.0 L / 0.97325
= 4.164 L.
Thus, the severity of a tropical storm is related to the depressed atmospheric pressure at its center, then the volume of the balloon is 4.164 L.
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Fill in the name and empirical formula of each ionic compound that could be formed from the ions in this table:
The empirical formula of the given ions and name of their compounds are given below:
Empirical formula : CoPO₄; Name : Cobalt (iii) phosphateEmpirical formula : FeCrO₄ ; Name : Iron (ii) tetraoxochromate (vi)Empirical formula : Cu(OH)₂ ; Name : Copper (ii) hydroxideWhat is empirical formula?Empirical formula is the simplest formula of a compound where the elements in the compounds are shown in their simplest combining ratios.
The empirical formula of some compound are equal to the molecular formula of the compound whereas in some other, compounds, the empirical formulas are multiples of the molecular formula.
The empirical formula of the given ions and name of their compounds are given below:
Cation: Co³⁺; Anion; PO³⁻ ; Empirical formula : CoPO₄; Name : Cobalt (iii) phosphate
Cation: Fe²⁺ Anion; CrO₄²⁻ Empirical formula : FeCrO₄ ; Name : Iron (ii) tetraoxochromate (vi)
Cation: Cu²⁺ Anion; OH⁻ Empirical formula : Cu(OH)₂ ; Name : Copper (ii) hydroxide
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In Act III of Romeo and Juliet, what does Friar Lawrence mean when he says, "O, then I see that madmen have no ears."
A. Angry people will not listen to reason.
B. Ears refers to ears of corn. Those who are hungry and without food go crazy.
C. Crazy people tend to cut off their own ears.
D. Romeo is being unreasonable and will not listen to him.
Answer:
D
Explanation:
most reasonable answer
The correct interpretation of Friar Lawrence's statement in Act III of Romeo and Juliet is: A. Angry people will not listen to reason.
In this scene, Friar Lawrence is expressing his frustration and realization that rational arguments and advice are ineffective when dealing with people who are consumed by anger or driven by their emotions. He sees that Romeo, who is filled with grief and rage after being banished, is not receptive to his reasoning and is acting impulsively.
The line suggests that when people are in a state of madness or extreme emotional turmoil, they become deaf to rational counsel and are unlikely to heed any advice or guidance.
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I forgot how to do fragment sentences
Answer:
A sentence fragment is a sentence that is missing either its subject or its main verb.
Explanation:
Incorrect: Went to the store yesterday.
Incorrect: After the classes, the library. My life nowadays
Complete combustion of 8.90 g of a hydrocarbon produced 27.3 g of CO₂ and 13.0 g of H₂O. What is the empirical formula for
the hydrocarbon? Insert subscripts as necessary.
Empirical formula is C4H7.
Empirical formula- A formula that lists the relative amounts of the constituent components in a compound without specifying the number or configuration of atoms.
When a hydrocarbon (CxHy) burns, CO2 and H2O are produced.
(Note: It mentions that a hydrocarbon is burned, which suggests that oxygen isn't present.)
moles of C in the compound: 44 g x 1 mol C/mole and 27.8 g CO2 x 1 mol CO2. = 0.632 moles of carbon
9.96 g H2O x 1 mol H2O/18 g x 2 mol H/mol H2O Equals 1.11 moles of H in the molecule.
We can calculate the mass and verify that it adds up to 8.70 g to rule out the presence of oxygen in the original molecule.
mass C=0.632 mol C times 12 g/mol equals 7.58 g C
H mass equals 1.11 mol H = 1.11 g H x 1 g/mol
Total mass Equals 8.69 g.
We may divide both by the lowest value (0.632), which will give us the lowest whole number of moles.
0.632/0.632 = 1.0 moles C
H = 1.11/0.632 = 1.75 moles.
Now we can multiply them by 4 to get H's whole number, which is-
C = 4 moles.
H = 7 moles
∴Empirical equation: C4H7
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Part A: Write a balanced nuclear equation for the fission reactions below.
1. Californium-252 undergoes spontaneous fission (no neutron collision) to produce xenon-140,
ruthenium-108, and an unknown number of neutrons. Write a balanced nuclear equation that
includes the correct number of neutrons produced. ( this is earth and space btw a form of science)
The spontaneous fission reaction is:
₉₈ Cf ²⁵² → ₅₄ Xe ¹⁵⁰+ ₄₄ Ru ¹⁰⁸ +4 ₀n¹
Given,
Californium-252 undergoes spontaneous fission to produce xenon-140, ruthenium-108, and an unknown number of neutrons.
The Nuclear reaction is
₉₈ Cf ²⁵² → ₅₄ Xe ¹⁵⁰+ ₄₄ Ru ¹⁰⁸ +4 ₀n¹
Spontaneous fission reaction always happens in heavier elements, that is the element with atomic numbers more than 89 and mass numbers greater than 230.
The nuclei of these elements are unstable and decay by radioactive decay in different forms like beta decay, positron, etc. At some percentage of the time, they decay by spontaneous fission.
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