The new overall heat transfer coefficient is 237.45 W-m-2.K-1, which is less than 60% of the initial value of 400 W-m-2.K-1, the boiler should be scheduled for cleaning. Therefore, the correct answer is option C: 237.45 W-m-2.K-1: Yes.
Using the following equation for calculating the overall heat transfer coefficient after one year of use:
1/U = 1/hi + δi/Ai + δo/Ao + 1/H0
Where hi and h0 are the heat transfer coefficients on the inner and outer surfaces of the tubes, δi and δo are the resistance factors on the inner and outer surfaces, and Ai and Ao are the inner and outer surface areas of the tubes.
Given that the overall heat transfer coefficient at installation was 400 W-m-2.K-1, we can plug in the values for the resistance factors and solve for the new overall heat transfer coefficient after one year of use:
1/U = 1/hi + δi/Ai + δo/Ao + 1/H0
1/400 = 1/hi + 0.0015/Ai + 0.0005/Ao + 1/H0
Assuming that the resistance factors are additive, we can use the following relationship to calculate the new heat transfer coefficients:
1/hi,new = 1/hi + δi/Ai
1/H0,new = 1/H0 + δo/Ao
Then, we can plug in the new heat transfer coefficients into the equation for overall heat transfer coefficient and solve for Unew:
1/Unew = 1/hi,new + δi/Ai + δo/Ao + 1/H0,new
Unew = 237.45 W-m-2.K-1
Since the new overall heat transfer coefficient is 237.45 W-m-2.K-1, which is less than 60% of the initial value of 400 W-m-2.K-1, the boiler should be scheduled for cleaning. Therefore, the correct answer is option C: 237.45 W-m-2.K-1: Yes.
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Which type of soil can hold absorb more water and why?
Clayey soil can absorb more water due to its comparatively large pore size and ability to hold the water molecules.
Soil is composed of components such as minerals, gas, water and organic matter. It is divided into three components viz. sand, silt and clay.
The ability of a soil to absorb water depends upon its pore size. In clayey soil, it has relatively large pore size so the water molecules can be easily absorbed and stored in the pores unlike sandy soil.
Clay particles have cohesive force between them which helps to hold water molecules together, whereas this cohesive force is absent in sandy soil.
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Which of the following characteristics of halogens is not
correct?
Their ionization energy decreases as atomic
a numbers increase
b
Their electronegativity decreases as atomic
numbers increase
с
Their electron affinity decreases as atomic
numbers increase
d None of the above
Answer: The correct answer is d - None of the Above.
Explanation: Halogens have increasing electron affinity as their atomic numbers increase, while their ionization energy and electronegativity both decrease as atomic numbers increase.
What is happening to the light when you see a green object?
A: The green light is absorbed
B: The green light is reflected .
C: The green light goes through the object.
Answer:
A. The green light is absorbed
The air pressure at the top of Mount
Everest is about 199 mm Hg.
What is the pressure on Everest in
atmospheres?
[?] atm
Answer:
[tex]\huge\boxed{\sf 0.26 \ atm}[/tex]
Explanation:
Given that,
Atmospheric pressure = 199 mm Hg
To convert mm Hg to atm, we divide by 760.So,
Pressure = 199/760 atm
Pressure = 0.26 atm[tex]\rule[225]{225}{2}[/tex]
Equipment not kept in your assigned lab drawer is called:
Shared equipment
Departmental equipment
Lab equipment
Community equipment
Equipment not kept in your assigned lab drawer is called: Shared equipment
Departmental equipment are the set of things that is to be used by all the people of department and not necessarily have to be a research equipment. This kind of equipment mostly include some simple machineries and all purpose equipment that can also be used out of the laboratory.
Lab equipment are strictly research related things but can be used for various projects and not strictly used for a particular project. This kind of equipment can be used by research scholars as well as undergraduate or postgraduate student group.
Community equipment are also research related thing but unlike Lab equipment it is used by a group of students or research scholars who are involved in same project or similar kind of project and can't be shared commonly among all the students.
A shared equipment is research related thing but unlike Community equipment it is not shared among the scholars of similar kind of different projects. Shared equipment is assigned for a single group for a particular project and can be shared among the group members only. No members of the group can acquire it all alone.
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draw the electron configuration for a neutral atom of iron.
The electron configuration for a neutral atom of iron (Fe) is [Ar] 3d^6 4s^2
The electron configuration is a way of describing the arrangement of electrons in an atom. It is written by listing the various electron shells and the number of electrons in each shell. In the case of iron, it has 26 electrons, which are arranged in the following way:
1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^6
The first two electrons go in the 1s orbital. The next two electrons go in the 2s orbital, and then six electrons go in the 2p orbitals. The next two electrons go in the 3s orbital, six electrons go in the 3p orbitals, and the last two electrons go in the 4s orbital. The last 6 electrons go in the 3d orbitals. The electron configuration shows that the last six electrons in the 3d orbitals are the valence electrons which are responsible for chemical reactions.
The element Iron (Fe) belongs to the group 8 of the periodic table, the elements of this group are known as transition elements, which have an incomplete d-subshell.
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PLEASE HELP IM ON A TIMER
a) The percentage abundance shows the amount of the isotope
b) The relative atomic mass is 122.5 amu
c) The Rutherford's model explained the planetary model of the atom.
What is the relative abundance?We have to know that the elements that we are considering must be composed of isotopes. The isotopes of the elements that we have have the same atomic number but does not have the same mass number of the element that we are looking at here.
For us to get the relative atomic mass of the element X;
Relative atomic mass = Weighted average of all the isotopes
As such we have;
(121 * 0.432) + (123 * 0.531) + (129 * 0.0370)
52.27 + 65.31 + 4.773
=122.35 amu
The Rutherford model of the atom was one of the earliest among the models of the atom and it helped in the understanding of the atom.
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Please help Chemistry
What is the percent yield of Fe2S3
if 284 g Fe2S3 are collected, rather
than the 863 g Fe2S3 expected
through calculation?
2FeBr3 +3Na₂S → Fe2S3 + 6NaBr
[ ? ]%
The percent yield of [tex]Fe_2S_3[/tex], according to the given parameters, would be 32.91%.
Percent yieldThe percent yield of a particular product from a reaction is the actual amount of that product formed relative to the stoichiometric or theoretical amount that is supposed to be formed.
The percent yield of a reaction can be mathematically expressed as:
Percent yield = actual yield/theoretical yield x 100%
In this case:
Actual yield = 284 g
Theoretical yield = 863 g
Percent yield = 284/863 x 100
= 32.91%
In other words, the percent yield of [tex]Fe_2S_3[/tex] according to the given parameters would be 32.91%.
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Answer:
first answer is correct in accellus
Explanation:
Glucose can be found in foods like honey. What happens to glucose in the body?
Answer: Unused glucose is stored mainly in the liver as glycogen.
Explanation: The body breaks down most carbohydrates from the foods we eat and converts them to a type of sugar called glucose. Glucose is the main source of fuel for our cells. When the body doesn't need to use glucose for energy, it stores it in the liver and muscles. This stored form of glucose is made up of many connected glucose molecules and is called glycogen. When the body needs a quick boost of energy or when the body isn't getting glucose from food, glycogen is broken down to release glucose into the bloodstream to be used as fuel for the cells.
When the body doesn't need to use glucose for energy, it stores it in the liver and muscles.
Chemit heated a olid red ubtance in a tube, the ubtance made a metallic liquid and a ga, which tatement bet decribe what happened to the red ubtance?
This is based on the process of chemical decomposition due to which experiment shows the red substance.
Compounds with an oxygen–oxygen single bond are categorised as peroxides. Hydrogen peroxide represents the simplest type of this group of chemicals.
It is characterized by its tendency to decompose, caused by the nature of its unstable peroxide bond. It must be stored with a stabilizer, such as acetanilide or similar organic materials.
The solution is not flammable, regardless of its concentration. However, hydrogen peroxide is a strong oxidizing agent, due to its chemical structure and unpaired electrons.
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Among the different types of scientific knowledge,
are likely to be modified or discarded most frequently. Long ago, in the 1600s, scientists discarded the phlogiston theory because
Many people in the early days of science thought that combustible stuff was made of a component called phlogiston that this substance was emitted during the burning of combustible things.
A combustible material is what?
Combustible materials are those that, when exposed to fire or heat, will ignite, burn, sustain combustion, or produce flammable gases in the form and circumstances anticipated for their application. Combustible materials include rubber, plastics, rubberized materials, and wood.
What gases are combustible?
A gas that really can ignite inside the air or with oxygen is said to be combustible. Gases like hydrogen, methane, propane, and iso-butane are examples of flammable gases. In the existence of an ignition source, a mixture containing a particular amount of flammable oxygen and gas will explode. The most common reason for gas explosion accidents is combustible gas.
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What is the empirical formula of a hypothetical compound that is 96%s and 4% h? you can do this problem easily in your head or with a piece of scratch paper.
The empiric formula to that compound is S₃H₄. Empirical formula is the proportion of the element that is available in a compound.
How to find the emperical formula of that compound?To find the formula for that compound, we have to know the mole ration of its atoms. As per given data only mass of s = 96% and h = 4%. We have to assume mass of the compound as x. Then calculate the ratio as follow:
S mole value : H mole value = (96x : 32.07) : (4x : 1.008)
S mole value : H mole value = 3x : 4x
Let divide the ratio with x
S mole value : H mole value = 3 : 4
After we get the ration, make the empiric formula based on it where the result:
S(mole value)H(mole value) = S₃H₄
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1. How many atoms would make 7.31 moles of potassium?
The number of atoms that would make 7.31 moles of potassium is 4.40 × 10²⁴ atoms.
How to calculate number of atoms?The number of atoms in a substance can be calculated by multiplying the number of moles in the substance by Avogadro's number as follows:
According to this question, there are 7.31 moles of pottasium. The number of atoms can be calculated as follows:
no of atoms = 7.31 moles × 6.02 × 10²³
no of atoms = 4.40 × 10²⁴
Therefore, 4.40 × 10²⁴ atoms is the number of atoms in pottasium.
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Why are plants so important to humans and other animals?
Answer:
Plants are a resource of food and are also responsible for turning CO2 into O2
Explanation:
I wasn't here to learn this can someone help me
A debate among scientists on how new species form is based on speciation.
Divergence explains how organisms on Earth are related because it shows how species are similar or different.
Genes play the role in diversity of carrying information that results in changes from one generation to the next.
Natural selection is part of evolution because it explains why attributes are either in existence or have gone extinct.
What do scientists debate about how species are formed ?One of the main debates among scientists on how new species form centers around the concept of speciation. There are two main hypotheses for speciation: allopatric speciation and sympatric speciation.
Divergence is the process by which different populations or species of organisms evolve from a common ancestor over time. This process is responsible for the diversity of life on Earth. By studying the similarities and differences between different organisms, scientists can infer evolutionary relationships.
Genes are the basic units of inheritance that carry information from one generation to the next. They play a crucial role in creating diversity among organisms. The genetic diversity of a population is the result of mutations, gene flow, and genetic drift.
The theory of natural selection is one of the most important and widely accepted explanations for the diversity of life on Earth. It is the process by which certain traits become more or less common in a population over time, depending on their impact on the survival and reproduction of the organisms that possess them.
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Alkaline (cold) perms(stronger)
What’s the approximate pH level?
What’s the main ingredient?
Is there a longer or shorter processing time?
The scale contains values from 0, which is the most acidic, to 14, which is an agricultural product that, though not always by weight majority, is the distinguishing or unique element in a cottage food product.
What differentiates one cuisine from another?A cuisine is a type of food distinguished by unique materials, preparation methods, and meals, and it is frequently related to a particular culture or geographical area. Dishes that are specific to a place are made possible by regional food preparation methods, customs, and ingredients.
Why is it vital to be aware of the many types of ingredients?To assess if a food product is a good decision or not, the ingredient list is the best resource you have at your disposal. In actuality, there is no other way to tell if a product is derived from actual food or if it also contains additives, added sugars, and vegetable oils.
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Explain how migration can be used by scientists to predict the trends in the size of the human population.
The way migration can be used by scientists to predict the trends in the size of the human population because Population growth occurs when immigration rates are higher than emigration rates; the opposite occurs when emigration rates are higher than immigration rates.
How do migration patterns play in population trends?The rate of natural rise and the results of migration make up the rate of population expansion. As a result, a high rate of natural increase can be balanced by a high level of net in-migration, and a low rate of natural increase can be.
Migration will slow down aging in wealthy areas while speeding it up in underdeveloped ones. Most nations and regions that are seeing population declines do so primarily as a result of natural change (the distinction
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which pictogram is not mandatory for chemical labels and sds?
Explosive (Symbol: exploding bomb)
Flammable (Symbol: flame)
Oxidising (Symbol: flame over circle)
Corrosive (Symbol: corrosion)
Acute toxicity (Symbol: skull and crossbones)
Hazardous to the environment (Symbol: environment)
Health hazard/Hazardous to the ozone layer (Symbol: exclamation mark)
Serious health hazard (Symbol: health hazard)
Gas under pressure (Symbol: gas cylinder)
SDS’s are not denote for consumers. An SDS affects the hazards of working with the material in an occupational fashion.
For example, an SDS for paint is not highly relevant to someone who uses a can of paint once a year but is extremely important to someone who uses that paint 40 hours a week or per day 5-6 hours.
A safety data sheet (SDS), first known as a material safety data sheet) is an important information source for eliminating or minimizing the risks linked with the use of hazardous chemicals (hazardous substances and/or dangerous goods) in workplaces.
While the GHS uses a total of 9 pictograms, OSHA will only impose the use of eight.
The environmental pictogram is not compulsory but may be used to provide additional information.
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How is our modern understanding of atomic structure different from thomson plum pudding model?
The negatively charged electron in the plum pudding model, however, is smaller than an atom and is negatively charged.
How does the nuclear model of the Rutherford scattering experiment compare to the plum pudding model?Electrons with a negative charge were encased in a positive charge, or "soup," in Thomson's plum pudding atom model. Rutherford's experiment with gold foil demonstrated that the majority of an atom is made up of empty space, with a small, compact, positively-charged nucleus. Rutherford put forth the nuclear model of the atom in response to these findings.The atom is the lowest unit of matter according to the hard-sphere atom model, which is why the plum pudding atom model is distinct. The negatively charged electron in the plum pudding model, however, is smaller than an atom and is negatively charged.To learn more about plum pudding model refer to:
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compound words are usually composed in the following order: combining form + word root + suffix.
Which of the following represents the second ionisation
energy of boron?
A B(g) → B²*(g) + 2e AH = + 2427 kJ mol-¹
B B*(g) → B²*(g) + e AH = + 2427 kJ mol-¹
C B(g) → B²(g) + 2e AH = -2427 kJ mot¹
D B*(g) → B²+ (g) + e AH = -2427 kJ mol-¹
E
A value of 25 °C is a measurement of
O distance.
O density.
O mass.
O volume.
O temperature
How is our modern understanding of atomic structure different from thomson’s plum pudding model?
So the plum pudding model is different from the hard-sphere model of the atom because in the hard sphere model of the atom, the atom is the smallest division of matter.
What is atom?Atom, smallest unit into which matter can be divided without the release of electrically charged particles. It also is the smallest unit of matter that has the characteristic properties of a chemical element. As such, the atom is the basic building block of chemistry.Investigate varying electron configurations in electron shells around an atom's nucleus.Investigate varying electron configurations in electron shells around an atom's nucleus See all videos for this articleMost of the atom is empty space. The rest consists of a positively charged nucleus of protons and neutrons surrounded by a cloud of negatively charged electrons. The nucleus is small and dense compared with the electrons, which are the lightest charged particles in nature. Electrons are attracted to any positive charge by their electric force; in an atom, electric forces bind the electrons to the nucleus.To learn more about electron refer to:
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Draw a Lewis structure for the urea molecule, CO(NH2)2CO(NH2)2.
Draw the Lewis dot structure for urea. Include all lone pairs of electrons.
A Lewis Structure is a significantly condensed illustration of the valence shell electrons of a molecule. It serves to illustrate how the electrons surround the character atoms of a molecule.
Water: Is It a Molecule?Atoms come together to form molecules. The two atoms a water molecule are either two hydrolysis (H) atom but one oxid (O) atom. As a result, water is sometimes shortened as H2O. One teaspoon of liquid contains billions of water molecules.
What sets a compound apart from a molecule?A molecule is a group of three or maybe more atoms connected by chemical bonds. A composite is a mixture created by the chemical fusion of a number of distinct types of components.
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How did the visigoths and Ostrogoths maintain a Roman style government
The First Germanic War and the crucial Battle of Anzio (378 CE), in which the Goths led by Fritigern overthrew Rome due to their oppression at the feet of Romans provincial rulers, were sparked
What is meant by provincial thinking?adjective. When you refer to someone or anything as provincial, you are expressing your disapproval of them because you find them to be monotonous and out of date. [disapproval] He made the choice to update the organization's rural image. Synonyms include local, exclusive, simpleminded, and uncultured More the opposites of provincial.
What does a provincial life entail?a member of or associated with a province. 2 pertaining to, or associated with, the provinces; regional. possessing beliefs and attitudes that are thought to be typical of country dwellers; simple or undeveloped; constrained.
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How would you measure 20 grams of salt?
20 grams of salt can be accurately weighed using an electronic balance. For measuring, we can use s filter paper or other thin sheets to take the salt.
What is an electronic balance ?An electronic balance is a used to weigh substances. Solid as well as liquids substances can be accurately weighed using an electronic balance. It is more accurate and easy to use in comparison with with the conventional balances.
Powder samples can be easily weighed out using electronic balances. First we have to tier the weight of the container or the paper on which the substance to be weighed is taken.
20 g of salt can be easily measured out using an electronic balance. Using this device we can take measurements with two or four decimal places as well.
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Instant hot and cold packs are found in many common stores and work when two substances react. Depending on the substances that react, the reaction either absorbs heat or gives off heat. The enthalpy of a hot pack is because the reaction.
Instant hot and cold packs are found in many common stores and work when two substances react. Depending on the substances that react, the reaction either absorbs heat or gives off heat. The enthalpy of a hot pack is negative because the reaction gives off heat. If The enthalpy of a hot pack is positive because the reaction absorbs heat.
Define enthalpy?A thermodynamic system's internal energy and the product of its pressure and volume are added to form enthalpy, which is one of the system's properties. It is a state function that is frequently used to monitor chemical, biological, and physical systems at a constant pressure that is conveniently given by the sizable surrounding environment.In a thermodynamic system with constant pressure, the total amount of heat is measured in terms of enthalpy. It is shown to be. H is equal to E + P + V, where E denotes internal energy, P denotes pressure, and E denotes energy. In a thermodynamic system, entropy represents the degree of chaos.The measurement of energy in a thermodynamic system is called enthalpy.To learn more about enthalpy refer to:
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Calculate the number of molecules present in 0.45 moles of H2O2.
Answer: 2.7099 × 10²² molecules
Explanation:
1 mole of H₂O₂ = 6.022 × 10²² molecules of H₂O₂
No . of molecules in 0.45 moles of H₂O₂ = 0.45 × 6.022 × 10²²
= 45/ 100 × 6.022 × 10²²
= 270.99 /100 × 10²²
= 2.7099 × 10²² molecules
∴ The no. of molecules present in 0.45 moles of H₂O₂ are 2.7099 × 10²² molecules .
Rosa was looking for patterns to help predict the products of chemical reactions. She recorded three similar decomposition reactions in the table. What products should she record in the last row of the table? 2licl + 3o2 3licl + 2o2 2lio + 3cl2 3lio+ 2cl2.
The products Rosa recorded in the last row of the table should be: 2LiCl + 3O₂.
The type of reaction which Rosa did is a decomposition reaction which involves one compound that yields to more than one (or usually two) product. To determine the product, we can deduce that it has to contain elements of Li, Cl and O₂. So, from the options, the answer is 2LiCl + 3O₂.
What is a decomposition reaction?A decomposition reaction can be described as a chemical reaction in which one reactant breaks down into two or more products. Generally, decomposition reactions need energy input.
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An umbrella i placed in a drink holding a volume of punch equal to 7ML. The height of the punch roe to 10 ML. If the ma of the umbrella wa 27G, what wa it denity?
An umbrella is placed in a drink holding a volume of punch equal to 7 mL. The height of the punch rose to 10 mL. If the mass of the umbrella was 27 g, the Density of the umbrella is 9 g/mL.
Given that :
The mass of the umbrella = 27 g
The volume of the umbrella :
= height of the punch rose - volume of the punch
= 10 mL - 7 mL
= 3 mL
The density of the umbrella is give as :
Density = mass / volume
Density = 27 g / 3 mL
Density = 9 g/mL
Thus, the density of the umbrella is 9 g/mL.
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