Answer:
Explanation:
Change is largely shunned in a traditional economy. This is because there are quite a few career choices and most people take the career path of their parents. Also, another example would be that, when it comes to accepting change they hardly do so, because it threatens the survival chances of their society. And as such, they don't really embrace change as it usually means they will have to let go of what they have known all their lives.
An element has an atomic number of 18 and an atomic mass of 40. The number of neutrons in the nucleus of an atom of this element is????
Answer: 22 neutrons
Explanation: 40 is the mass number = atomic mass = total number of protons and neutrons in atomic nucleus
18 is the number of protons in the nucleus of this atom
Then 40 - 18 = 22 neutrons
and this is Argon
Which example is most likely an inorganic compound?
A. methane, which is made of carbon and hydrogen
B. glucose, which is a sugar made by plants
C. sodium chloride, which is a salt
D. human DNA, which is a molecule in cells
Answer: Easy,the answer is the letter D
Which statement best describes pseudoscience
Answer:
The statement that best describes pseudoscience is that it lacks a process for collecting data
Answer: not a branch of science and involves beliefs and opinions
Explanation:
Perform the following
mathematical operation, and
report the answer to the correct
number of significant figures.
]
0.0003/162 = [ ? ]x10
Answer:
1.85 × 10⁻⁶
Explanation:
0.0003 ÷ 162 = 1.851851852 × 10⁻⁶ ⇒ 1.85 × 10⁻⁶
Hope that helps.
The significant figure in the answer should be one here, since the number 0.0003 contains only one significant figure. Hence, the answer is 2 × 10⁻⁶.
What is significant figure ?Significant figures are digits in a quantity with certain values along with some uncertain digits. The counting of significant figures of a number should follow some rules.
The zeros after the decimal point which is not following a nonzero number are not significant. Therefore, there is only one significant figure in the number 0.0003.
For any arithmetic operation, the number of significant figures in the result should be equal to the one in operation that is with least significant figures.
Here. 162 have 3 significant figures. Therefore, the result should contain only one significant figure.
0.0003 /162 = 1.85 × 10⁻⁶.
Then the result with correct significant figures is rounded to 2 × 10⁻⁶.
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The alpha decay of a radioactive nuclide (X) emits a He-4 nucleus and produces an isotope of Superscript 235 subscript 92 upper U.. What is X?
Answer: Thus X is Plutonium
Explanation:
Alpha Decay: In this process, a heavier nuclei decays into lighter nuclei by releasing alpha particle. The mass number is reduced by 4 units and atomic number is reduced by 2 units.
General representation of alpha decay :
[tex]_{Z}^{A}\textrm{X}\rightarrow _{Z-2}^{A-4}\textrm{Y}+_2^4\textrm{He}[/tex]
where Z = atomic number
A= mass number
X and Y = atomic symbol of elements
[tex]_{Z}^{A}\textrm{X}\rightarrow _{92}^{235}\textrm{U}+_2^4\textrm{He}[/tex]
Thus [tex]_{94}^{239}\textrm{Pu}\rightarrow _{92}^{235}\textrm{U}+_2^4\textrm{He}[/tex]
Thus X is Plutonium with atomic number 94 and mass number 239
Answer:
the answer is D on edge
Explanation:
describe how 250 cm³ of 0.2 mol/dm³ H2SO4 could be prepared from 150 cm³ of 1.0mol/dm³ stock solution of the acid
Answer:
Explanation:
250 cm^3 of 0.2 moldm-3 H2SO4 can be prepared from 150cm^3 of 1.0 moldm^-3 by dilution.
150cm^3 of the 1.0 moldm^-3 stock solution is measured out using a measuring cylinder and transferred into a 250 cm^3 standard volumetric flask and made up to mark. The resulting solution is now 250cm^3 of 0.2 moldm-3 H2SO4.
how many w atoms are found in 0.43 moles of pure w
So, neon has a molar mass of 20.18 g/mol , which means that every mole of neon has a mass of 20.18 g . Now, you know that one mole of any element contains exactly 6.022⋅1023 atoms of that element - this is Avogadro's number.
Hope this helped
differences between plant and animal cells, other than their vacuoles
Answer:
The difference between the two is that plant have three extra "components" than animal. The three extra components include a different sort of vacuole, chloroplast, and a cell wall.
Explanation:
Compare the physical properties of two forms of carbon: diamond and graphite
Diamond and graphite are allotropes of carbon and have various differences in their physical properties.
Explanation:
Diamond:
It is crystalline in natureEach Each C is [tex]sp^{3}[/tex] hybridized and forms 4 covalent binds with neighboring C atomsThe geometry is tetrahedralC-C bond length is 154 pmIt has rigid covalent boning which is difficult to break.It acts as an electric insulatorGraphite:
It has layered structureEach C atom is sp2 hybridized and forms 3 sigma bonds with 3 other C atoms. Fourth electron forms pi bond. The geometry is planarC-C bond length is 141.5 pmIt is soft. Its layers can be separated easilyIt is good conductor of electricity.This is the comparison of the physical properties of two forms of carbon: diamond and graphite
Carbon and Diamond are allotropes of carbon having different physical properties.
What are the physical properties of Carbon and Diamond?Diamond is vary hard whereas graphite is soft;In diamond there is a three dimensional network of strong covalent bonds. This makes diamond extremely hard.
On the other hand, in graphite there are flat layers of carbon atoms. These layers are held by weak van der Waal’s forces and hence can easily slip one over the other. This makes graphite extremely soft and slippery.
Diamond is bad conductor of electricity whereas graphite is a good conductor:In diamond all the four valence electrons carbon are involved in covalent bonds and are not free to conduct electricity. This makes diamond a bad conductor of electricity. In graphite, the fourth valence electron is relatively free, can move from one carbon atom to the other in a layer, and hence is responsible for conducting electricity. Hence, graphite is a good conductor of electricity.
Melting points of graphite and diamond are very high:In diamond as well as in graphite carbon atoms are held by strong net work of covalent bonds. Therefore, both have very high melting points.
Therefore, we can compare the physical properties of carbon and diamond.
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how will you measure the length of a curved line by using a thread?
The dimensions of a box are 4.5 cm wide by5.750 cm long by 1.50 cm tall. What is the volume of the box taking significant figures into account?
The volume of the box taking significant figures into account is 38.8125 ≈39 cm³.
What do you mean by volume?
The amount of space occupied by a three-dimensional object or region of space, expressed in cubic units (cm³).
It means, the amount of three dimensional space that a closed figure can occupy is measured by its volume.
Formula for volume=length ×breadth ×height
To calculate the volume of the box,
volume=length × breadth × height
volume=4.5×5.750×1.50
volume=38.8125 ≈39 cm³.
Hence, the volume of the box taking significant figures into account is 38.8125 ≈39 cm³.
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a flask contains 0.25 naoh. what mass of naoh is present per dm3 of solution
Answer:
30 g 0f NaOH.
Explanation:
The following data were obtained from the question:
Molarity of NaOH = 0.25 M
Volume = 3 dm³
Mass of NaOH =?
Next, we shall determine the number of mole of NaOH present in 3 dm³ of 0.25 M NaOH solution.
This can be obtained as follow:
Molarity of NaOH = 0.25 M
Volume = 3 dm³
Mole of NaOH =?
Molarity = mole /Volume
0.25 = mole of NaOH/3
Cross multiply
Mole of NaOH = 0.25 × 3
Mole of NaOH = 0.75 mole
Finally, we shall determine the mass of NaOH as follow:
Mole of NaOH = 0.75 mole
Molar mass of NaOH = 23 + 16 + 1 = 40 g/mol
Mass of NaOH =.?
Mole = mass /Molar mass
0.75 = mass of NaOH /40
Cross multiply
Mass of NaOH = 0.75 × 40
Mass of NaOH = 30 g
Therefore, 30 g 0f NaOH is present in the flask.
The mass of NaOH in 0.25 M sample has been [tex]\rm\bold{ 30\;g/dm^3}[/tex].
The molarity has been defined as moles of sample present in a liter of solution.
The molarity of given NaOH solution has been 0.25 M. It has been stating that 0.25 moles of NaOH has been present in a liter of solution.
The mass of sample present in 1 cubic decimeter has been the mass of sample in a liter of solution as:
[tex]\rm 1\;dm^3=1\;L[/tex]
The molarity (M) has been given as:
[tex]M=\dfrac{\text {mass}}{mwt}\;\times\;\dfrac{1}{V(L)}[/tex]
Where, the molarity of NaOH sample has been, [tex]M=0.25\;\text M[/tex]
The molar mass of NaOH has been, [tex]mwt=40\;\text {g/mol}[/tex]
The volume of solution has been, [tex]V=3 \;\text L[/tex]
Substituting the values for mass of NaOH:
[tex]0.25=\dfrac{mass}{40}\;\times\;\dfrac{1}{3} \\mass=0.25\;\times\;40\;\times\;3\\mass=30\;\text g[/tex]
The mass of NaOH in 0.25 M sample has been [tex]\rm\bold{ 30\;g/dm^3}[/tex].
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What is significant about a temperature of 37 degrees Celsius? Explain your answer
Please help me
Explanation:
For most folks, a thermometer reading around 98.6 degrees Fahrenheit (37 degrees Celsius) means their body temperature is normal. Now, two scientists have an idea why our bodies, as well as those of most other mammals, consistently run at that temperature : A toasty body temperature helps keep nasty fungal infections at bay.
"One of the mysteries about humans and other advanced mammals has been why they are so hot compared with other animals," said study co-author Arturo Casadevall, professor and chair of microbiology and immunology at Albert Einstein College of Medicine of Yeshiva. "This study helps to explain why mammalian temperatures are all around 98.6 degrees Fahrenheit."
Casdevall's previous work showed that the number of fungal species that can thrive and, therefore, infect an animal declines by 6 percent for every 1.8 degree F (1 C) rise in temperature. This, he claimed, is why reptiles , amphibians and other cold-blooded animals are susceptible to tens of thousands of fungal species, whereas only a few hundred types of fungi can harm humans and other mammals.
What is the volume of a book that is 22.0 cm tall, 13 cm wide, and 3.2 cm thick? Use sig figs and correct units
1. 915.2 cm
2. 920 cm
3. 920 cm^3
4. 915 cm^3
Answer:
4. 915 cm^3
Explanation:
Length = 22.0cm
Breadth = 13 cm
Thickness = 3.2 cm
Volume = Length * Breadth * Thickness
Volume = 22 * 13 * 3.2
Volume = 915.2 cm^3
Volume = 915cm^3. The correct option is option 4.
If 10.0 moles of O₂ are reacted with excess NO in the reaction below, and only 4.2 mol of NO₂ were collected, then what is the percent yield for the reaction? 2 NO (g) + O₂ (g) → 2 NO₂ (g)
Answer:
Percent yield = 21%
Explanation:
Find:
Percent yield
Computation:
1 mol O₂ produces 2 mol NO₂
So,
10 mol O₂ produces 20 mol NO₂
Percent yield = [Actual yield / Theoretical yield]100
Percent yield = [4.2 / 20]100
Percent yield = 21%
The percent yield for the reaction is 21%
From the question,
We are to determine the percent yield for the reaction.
First, we will determine the theoretical yield for the reaction
From the given balanced chemical equation for the reaction
2 NO (g) + O₂ (g) → 2 NO₂ (g)
This means,
2 moles of NO reacts with 1 mole of O₂ to produce 2 moles of NO₂
From the given information,
Number of moles of O₂ that reacted = 10.0 moles
Since,
2 moles of NO reacts with 1 mole of O₂ to produce 2 moles of NO₂
Then,
2×10 moles of NO will be required to react with the 10 moles of O₂ to produce 2×10 moles of NO₂
That is,
20 moles of NO will be required to react with the 10 moles of O₂ to produce 20 moles of NO₂
∴ 20 moles of NO₂ will be produced during the reaction.
This is the theoretical yield
Now, for the percent yield of the reaction,
Using the formula
[tex]Percent\ yield = \frac{Actual\ yield }{Theoretical\ yield} \times 100\%[/tex]
From the question
Actual yield = 4.2 mole
∴ Percent yield for the reaction = [tex]\frac{4.2}{20 }\times 100\%[/tex]
Percent yield for the reaction = [tex]\frac{420}{20}\%[/tex]
Percent yield for the reaction = 21%
Hence, the percent yield for the reaction is 21%
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50 POINTS
Match each item with the correct statement below:
1.) The fact that matter can be neither created nor destroyed in a chemical change.
2.) Substance that changes to a gas easily at room temperature.
3.) Any chemical reaction that absorbs energy.
4.) Can be observed only when there is a change in composition of a substance.
5.) Any chemical reaction that gives off energy.
6.) The amount of matter contained in a unit of volume.
7.) The type of change in which the identity of substances does not change.
8.) The change of one or more substances into other substances.
9.) Can be observed without any change in the identity of the substance.
10.) Another term for chemical change.
chemical property
physical change
physical property
chemical change
density
law of conservation of mass
chemical reaction
volatile
endothermic
exothermic
energy
Answer:
1) law of conservation of mass
2) volatile
3) endothermic
4) chemical property
5) exothermic
6) density
7) physical change
8) chemical change
9) physical property
10) chemical reaction
What is the volume of an 2.3 M
solution with 212 grams of calcium
chloride () dissolved in it?
A 0.01
B. 1911
G: 0.83
D.4.39
Answer:
830 mL or 0.83L
Explanation:
For molecules with only one central atom, how many lone pairs on the central atom guarantees molecular polarity?
Answer:
The answer is "1".
Explanation:
It is the lone pairs at, which the central atom provides the molecular and the polarity. It is only for substances with just a central atom, for which the molecules with only one central atom and only one of the solitary paired were required, that's why in this question the "1" is the correct answer.
The standard enthalpy of formation (ΔHf°) of calcium carbonate is –1207 kJ/mol. Which ONE of the equations below has ΔH° = –1207 kJ? A) Ca(s) + C(s) + 3/2 O2(g) –––––> CaCO3(s) B) 2 Ca(s) + 2 C(s) + 3 O2(g) –––––> 2 CaCO3(s) C) Ca(s) + C(s) + 3 O(g) –––––> CaCO3(s) D) CaCO3(s) ––––> Ca(s) + C(s) + 3/2 O2(g) E) CaO(s) + CO2(g) –––––> CaCO3(s)
Answer:
A) Ca(s) + C(s) + 3/2 O₂(g) → CaCO₃(s)
Explanation:
Standard enthalpy of formation of a chemical is defined as the change in enthalpy durin the formation of 1 mole of the substance from its constituent elements in their standard states.
The consituent elements of calcium carbonate, CaCO₃, in their standard states (States you will find this pure elements in nature), are:
Ca(s), C(s) and O₂(g)
That means, the equation that represents standard enthalpy of CaCO₃ is:
A) Ca(s) + C(s) + 3/2 O₂(g) → CaCO₃(s)Is the equation that has ΔH° = -1207kJ/mol
What happens to the particles and energy of a substance as it changes temperature or changes state.(solid to liquid to gas) and vice versa :(gas to liquid to solid.
Answer:
When changing state of aggregation, the particles change their kinetic energy, decreasing or increasing, if their kinetic energy decreases the collision between the particles is less, and therefore less heat is released and more space will exist between them, this is an example of the states of aggregation that occupy large expandable volumes such as gas.
As the particles get closer, the molecules are closer and collide in a greater way, thus generating that the kinetic energy increases, the friction also and these particles are closer to each other, compressing the space and limiting their movement up to a point.
Explanation:
The states are three, solid liquid and gaseous-
In the solid state there is less distance between the particles, greater density of the body and greater force of friction or collision.
On the other hand, in the solid state the particles are more distended but up to a limit they expand, different from the gaseous state that their particles expand more and without a limit.
The states are modified according to the different temperatures that the body undergoes, at a higher temperature a higher kinetic energy and greater friction are usually reached, generating relaxed states such as liquid and gas, and at lower temperatures it is the reverse effect.
Which describes human-made polymers? synthetic subunit natural macromolecule
Answer:
Synthetic
Explanation:
I just took the quiz and got it right
Answer:
A- Synthetic
Explanation:
just took the quiz
If anyone is good at chemistry do you mind helping :)
Answer:
• 1.62432 moles of nitrogen
• Tire Pressure: 2.74 * 10⁵ Pa
• The tires will burst
• Pressure: 244 kPa
Explanation:
• We can determine the number of moles of nitrogen using the formula pV = nRT, where p = pressure, V = volume, n = number of moles, R = gas constant, and T = absolute temperature.
Now remember we have our initial pressure in kilopascals so let's convert to pascals (249 pascals). The volume is given in liters, so let's convert into m². And the initial temperature is given in Celsius ⇒ our absolute temperature in Kelvins.
[tex]\mathrm{p\:}=\mathrm{249 kPa\:} = \mathrm{2.49 * 10^5\:},\\\mathrm{15.6L\:} =\mathrm{0.0156m^2\:},\\\mathrm{R\:}=\mathrm{8.314J/mol*K\:},\\\mathrm{T\:}=\mathrm{21C\:} + \mathrm{273\:}=\mathrm{294K\:}[/tex]
Respectively the moles of nitrogen in each tire should be:
[tex]\mathrm{n\:}=\mathrm{pV/RT\:}=\mathrm{(2.49*10^5)(0.0156)/(8.314)(294)\:}=\frac{\left(2.49\cdot \:10^5\right)\left(0.0156\right)}{\left(8.134\right)\left(294\right)}=\frac{3884.4}{2391.396}\\[/tex]
[tex]= 1.62432\dots \mathrm{moles\:}\mathrm{of\:}\mathrm{nitrogen\:}[/tex]
• We can solve this part similarly. All our values will be the same, besides the temperature, as we have to consider both the initial and final temperature here.
[tex]\mathrm{T_2\:}=\mathrm{51C+ 273\:} }=\mathrm{324K\:} }[/tex] -
[tex]\mathrm{p_2\:}=\mathrm{(2.49*10^5)(324)/(294)\:} }=\frac{\left(2.49\cdot \:10^5\right)\left(324\right)}{294}=\frac{40338000}{147}=274408.16326\dots[/tex]
[tex]=2.74408.16326*10^5\dots\mathrm{Pa}[/tex]
• The text mentions that the tires will burst when the internal pressure reaches 269kP. From part #2 we know that the final pressure will be, in kilopascals, 274kP. As 274 > 269, the tires will burst in Death Valley.
• We would want the final temperature = breaking pressure. Therefore,
[tex]\mathrm{p_2\:}=\mathrm{(269)(294)/(324)\:} }=\frac{79086}{324}=\frac{13181}{54}=244.09259\dots\mathrm{kPa\:} }[/tex]
what are non metal and metals
Answer:
metals are are solids and has high melting point( except mercury and can also conduct heat and electricity, where non-metals may be solids also but,is brittle such as :diamonds etc... Its a bad conductor for heat and has low melting points
a loaf of bread has a mass of 500 g and volume of 2500 cm3 . what is the density of the loaf of bread
Answer: the density of the bread is 0.2g per 1 cm3
Explanation: density is defined as mass per volume d= m/v so we can calculate 500g÷ 2500cm3= 0.2g/1 cm3
Name a device or other object whose major purpose is to convert
chemical energy into light energy.
Answer:
Storage battery oe cell
Explanation:
The storage battery or cell is a device that coverts chemical energy into light energy when required.
During charging of battery, there is some chemical changes in the battery and absorb energy. The absorbed energy is converted into electrical energy when connected to an external load.
Hence, the correct answer is "Storage battery or cell".
Which statement correctly describes the condensationof a gas?
Answer:
Condensation starts to occur throughout the liquid instead of just on the surface.
If the pressure of the gas in a 2.31 L balloon is 0.12 atm and the volume increases to 7.14 L, what will be the final pressure of the air within the balloon
Answer:
.0388 atm
Explanation:
Since temperature is not given , we assume that it is constant . So we can apply Boyle's law . According to it
P₁ V₁ = P₂ V₂
P₁ and V₁ are pressure and temperature initially and P₂ and V₂ are pressure and volume finally .
Putting the given values
.12 x 2.31 = 7.14 x P₂
P₂ = .12 x 2.31 / 7.14
= .0388 atm .
which of the following will have highest boiling point
(A) 0.1 M FeCl3
(B) 0.1 M Urea
(C) 0.1 M NaCl
(D) 0.1 M Glucose
I NEED HELP PLEASEEE
Answer:
activasion energy
Explanation:
How does potential energy transform into kinetic energy?
Answer:
When an object is allowed to fall,the concentrated gravitational potential energy is converted into the kinetic energy of motion. if there is no air resistance or other restrictions all of the potential energy will be converted to kinetic energy when the object has fallen the distance H
Explanation
When an object is allowed to fall,the concentrated gravitational potential energy is converted into the kinetic energy of motion. if there is no air resistance or other restrictions all of the potential energy will be converted to kinetic energy when the object has fallen the distance H