Answer:
the anserw is 2
Explanation:
The presence of dark matter is one piece of evidence that supports the Big Bang theory. Why is this substance called dark matter?
A. The term dark matter describes matter that is so dark in color that it is barely visible with observation instruments such as telescopes.
B. The term dark matter describes the vast areas of the universe where light cannot be seen.
C. The term dark matter describes black holes because they absorb light.
D. The term dark matter describes matter that cannot be seen because it does not give off light. It can only be detected by observing its gravitational effects on other types of matter.
THIS CLASS IS !!!!EARTH SCIENCE!!!!
The substance is called dark matter because the term dark matter describes matter that cannot be seen because it does not give off light. It can only be detected by observing its gravitational effects on other types of matter (option D).
What is dark matter?Dark matter in physics or astronomy are particles of matter that cannot be detected by their radiation but whose presence is inferred from gravitational effects.
According to this question, the presence of dark matter is one piece of evidence that supports the Big Bang theory.
However, this matter is called "dark" because it does not appear to interact with the electromagnetic field i.e. it does not absorb, reflect, or emit electromagnetic radiation and is, therefore, difficult to detect.
Therefore, the substance is called dark matter because the term dark matter describes matter that cannot be seen because it does not give off light. It can only be detected by observing its gravitational effects on other types of matter.
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Why do you think the mass of the egg changed in water and salt water?
Which compound listed below has the largest molar mass?
Ca(OH)2
H20
CaCl2
NH3
Answer: the answer would be CaCI2
Explanation: this was one of my exam questions i got right. :)
How would you change the distance between two charged particles to increase the electric force between them by a factor of 25?
Answer:
reduce the distance by the factor of 5
2. The combustion of octane is -47.5 kJ/g.
a. Write the reaction for the combustion of octane.
b. What is the value of the enthalpy of combustion for octane per mole?
c. If the enthalpy of combustion was written with the reaction, what value would be
used?
The enthalpy of combustion per mole is -5397.7 kJ/mol.
What is combustion?The term combustion refers to a reaction in which a substance is burnt in oxygen. Now we know that octane is a hydrocarbon and its combustion follows the general equation for the combustion of hydrocarbons.
[tex]2C_{8}H_{18} (g) + 25O_{2} (g)---- > 16CO_{2} (g) + 18H_{2} O(g)[/tex]
Given that the number of moles in one gram of octane is obtained from;
1g/114 g/mol = 0.0088 moles
If the burning of 0.0088 moles of octane produces -47.5 kJ
Burning of 1 mole of octane would produce 1 mole * -47.5 kJ/0.0088 moles
= -5397.7 kJ/mol
We can now write is as;
[tex]2C_{8}H_{18} (g) + 25O_{2} (g)---- > 16CO_{2} (g) + 18H_{2} O(g)[/tex] ΔH = -5397.7 kJ/mol
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You have used 2. 6×102 L of distilled water for a dialysis patient. How many gallons of water is that?
By unit conversion, the distilled water for dialysis in gallons is 68.69 gallons.
We need to know about unit conversion to solve this problem. The unit conversion can be used to convert a unit to another unit. It can be defined as
a = xb
where a is unit a, b is unit b and x is the constant of conversion.
From the question above, we know that
V = 2.6 x 10² liters
The unit conversion that we used is (1 gal = 3.785 liters)
V = 2.6 x 10² liters
V = 2.6 x 10² / 3.785 gal
V = 68.69 gallons
Hence, the distilled water for dialysis in gallons is 68.69 gallons.
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. Both element K and element L are found in period 3 of the periodic
table. If K is in group 13 while L is in group 15, which of the two
has a greater atomic number? Explain.
Answer: L element has greater atomic number.
Explanation:
The periodic table contains vertical columns called as groups and horizontal rows called as periods.
Period 3 contains 8 elements which are sodium, magnesium , aluminium , silicon , phosphorous , sulphur, chlorine and argon.
K element which belongs to group 13 is aluminium with atomic number of 13 . L element which belongs to group 15 is phosphorous with atomic number of 15.
Thus L element has greater atomic number.
8. An elevator is moving upward with a speed of 11 m/s. Three
seconds later, the elevator is still moving upward but its
speed has been reduced to 5 m/s. What is the elevator's
acceleration?
Answer:
Average acceleration = - 2 m/s^2
Explanation: Have a nice day
When a car takes a sharp turn to the left and the person in the car slides to the right, this
is an example of
A. Newton's First Law of Motion
B. Newton's Second Law of Motion
C. Newton's Third Law of Motion
D. Newton's Law of Gravity
Answer:
It is newtons First Law:)
Explanation:
ice _______________ - a collective term for several mechanical weathering processes induced by stresses created by the freezing of water into ice.
Answer: Frost weathering is a collective term for several mechanical weathering processes induced by stresses created by the freezing of water into ice.
An atom has a diameter of 2.00 Å and the nucleus of that atom has a diameter of 7.50×10−5 Å . Determine the fraction of the volume of the atom that is taken up by the nucleus. Assume the atom and the nucleus are a sphere
Answer:
The fraction of the volume of the atom that is taken up by the nucleus is 4.6656\times 10^{-14}4.6656×10
−14
.
The density of a proton is 6.278\times 10^{14} g/cm^36.278×10
14
g/cm
3
.
Explanation:
Diameter of the atom ,d = 2.50 Å
Radius of the atom ,r = 0.5 d=0.5 × 2.50 Å = 1.25Å
Volume of the sphere= \frac{4}{3}\pi r^3
3
4
πr
3
Volume of atom = V
V=\frac{4}{3}\pi r^3V=
3
4
πr
3
..[1]
Diameter of the nucleus ,d' = 9.00\times 10^{-5}\AA9.00×10
−5
A
˚
Radius of the nucleus ,r' = 0.5 d'=0.5\times 9.00\times 10^{-5}\AA=4.5\times 10^{-5}\AA0.5×9.00×10
−5
A
˚
=4.5×10
−5
A
˚
Volume of nucleus = V'
V=\frac{4}{3}\pi r'^3V=
3
4
πr
′3
..[2]
Dividing [2] by [1]
\frac{V'}{V}=\frac{\frac{4}{3}\pi r'^3}{\frac{4}{3}\pi r^3}
V
V
′
=
3
4
πr
3
3
4
πr
′3
=\frac{r'^3}{r^3}=\frac{(4.5\times 10^{-5}\AA)^3}{(1.25 \AA)^3}=
r
3
r
′3
=
(1.25
A
˚
)
3
(4.5×10
−5
A
˚
)
3
\frac{V'}{V}=4.6656\times 10^{-14}
V
V
′
=4.6656×10
−14
The fraction of the volume of the atom that is taken up by the nucleus is 4.6656\times 10^{-14}4.6656×10
−14
.
Diameter of the proton ,d = 1.72\times 10^{-15} m = 1.72\times 10^{-13} cm1.72×10
−15
m=1.72×10
−13
cm
1 m = 100 cm
Radius of the proton,r = 0.5 d=0.5\times 1.72\times 10^{-13} cm=8.6\times 10^{-14} cm0.5×1.72×10
−13
cm=8.6×10
−14
cm
Volume of the sphere= \frac{4}{3}\pi r^3
3
4
πr
3
Volume of atom = V
V=\frac{4}{3}\times 3.14\times (8.6\times 10^{-14} cm)^3=2.664\times 10^{-39}cm^3V=
3
4
×3.14×(8.6×10
−14
cm)
3
=2.664×10
−39
cm
3
Mass of proton, m = 1.0073 amu = 1.0073\times 1.66054\times 10^{-24} g1.0073×1.66054×10
−24
g
1 amu = 1.66054\times 10^{-24} g1amu=1.66054×10
−24
g
Density of the proton : d
d=\frac{m}{V}=\frac{1.0073\times 1.66054\times 10^{-24} g}{2.664\times 10^{-39}cm^3}=6.278\times 10^{14} g/cm^3d=
V
m
=
2.664×10
−39
cm
3
1.0073×1.66054×10
−24
g
=6.278×10
14
g/cm
3
The density of a proton is 6.278\times 10^{14} g/cm^36.278×10
14
g/cm
3
.
Explanation:
set as brainliest
Two students are given different samples of a substance and are instructed to determine the properties of the substance.
Which statement describes a property that will be the same for both students?
color because it is an extensive property
mass because it is an extensive property
boiling point because it is an intensive property
volume because it is an intensive property
Answer:
C) Boiling point because it is an intensive property.
The statement describes a property that will be the same for both students is (B). mass because it is an extensive property Hence Option (B) is correct.
What is an Extensive Property ?A property known as an extensive property depends on the quantity of materials in a sample. A couple of instances of extensive attributes are mass and volume.
According to how a property varies as the system's size changes, physical qualities of materials and systems are sometimes classified as either intensive or extensive.
Therefore, The statement describes a property that will be the same for both students is (B). mass because it is an extensive property Hence Option (B) is correct.
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20 POINTS. What happened to a Gas once thermal energy is removed. What happened to a Gas once Thermal energy is added? Be specific!
When thermal energy is added the gas will become more dense as the atoms come closer together and when thermal energy is added it becomes less dense as the atoms move apart
What were the purposes of this document? Check all that apply. to extend the rights of sovereignty to all states in the Union to declare rights and powers of the United States to mobilize the Louisiana militia for the coming war to dissolve the political bonds between Louisiana and the United States to declare that Louisiana was a free and independent state
Answer:
Sorry that I'm late but the correct answers are to dissolve the political bonds between Louisiana and the united states and to declare that Louisiana was a free and independent state, or D and E
Explanation:
Answer:
The last two
Explanation:
Which element would most likely bond with lithium and form an ionic compound?
Answer:
(Please make sure to re-write this on your own to make sure that your teacher doesn't think your cheating!) Fluoride.Explanation:Ionic bonding is the type of bond that is made between a nonmetal and a metal. In this type of union, one of the elements yields electrons and the other accepts electrons.
In this case, the metal is Lithium, we need a nonmetal to complete the union. (Don't know if you need this or anything but here you go)
Beryllium is a metal.
Calcium is a metal.
Fluoride is a nonmetal.
Sodium is a metal.
After the analysis, we conclude that the correct answer is Fluoride since it is the only one that is a nonmetal.
Well i still kinda don't get the differences of climate and weather.so what i need help with is what are the differences of climate and weather?
Answer:
climate
Explanation:
climate is the weather conditions for a long period of time, weather is the short term conditions of a location. The answer would be climate because the general climate is colder.
Answer:
D climate
Explanation:
Alright here is a sum up, Weather is the rain, coldness, heat all through the days, like tommorow will be raining. that is weather, weather = short term. climate is the area on the equator, so florida will be warmer than canada, so climate = long term
2. Water is an example of a(n)
a. inorganic b. organic
compound.
d. none of these
c. carbon
it would be A ,inorganic Compound
which is an expression of molality
Answer:The formula for molality is m = moles of solute / kilograms of solvent.
Explanation:
What is it called when electrons fall back down to their normal energy level and release a photon of light? (Please help I think its called a quantum leap but im not sure!!)
Answer: Photoelectric effect
Explanation:
Which test uses color change to reveal oil-based paints?
mass spectometry
gas chromatography
potassium hydroxide test
ethanol test
Answer:
potassium hydroxide test
Explanation:
The test that uses color change to reveal oil-based paints is the potassium hydroxide test. The correct option is c.
What is a potassium hydroxide test?The KOH (potassium hydroxide) approach is used to test for yeast in specimens. Potassium hydroxide acts as an enzymatic agent, breaking down detritus in a specimen, such as epithelial cells and WBCs, allowing yeast or pseudohyphae to be seen.
The potassium hydroxide prep test is used to detect fungal diseases on the skin or in the nails. A scrape of cells from the afflicted area is examined under a microscope for evidence of fungus. The potassium hydroxide skin lesions exam, fungal smear, or skin scraping are other names for the potassium hydroxide test.
Therefore, the correct option is the c, potassium hydroxide test.
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PLS ANSWER THESE 3 QUESTIONS WHICHEVER YOU KNOW!!
1.For an object at rest, the normal force equals the gravitational force. What is the sum of these forces called?
·ω·
A Net force
B Unbalanced force
C Inertia
D Potential force
2. Which of the following best describes the forces when there are different-sized forces from opposite directions acting on an object?
a Positive
b Negative
c Unbalanced
d Gravitational
3. An object is at rest on a table. The gravitational force is 10 N down, and the normal force is 10 N up. What is the net force?
An object at rest on a table. An arrow pointing down represents 10 newtons of gravitational force. An arrow pointing up represents 10 newtons of normal force.
a 10 N up
b 0 N
c 10 N down
d 20 N up
Answer:
I only know 3 its 0 N because 10-8=2 and 2-2=0
Explanation 10-8=2 2-2=0
Which of the following definitions best describes a parallel of latitude?
a--A line that is drawn horizontally around the earth and is parallel to the Prime Meridian.
b---A line that is drawn vertically down the earth and is parallel to the equator.
c--A line that is drawn vertically down the earth and is parallel to the Prime Meridian.
d--A line that is drawn horizontally around the earth and is parallel to the equator.
The statement that express the definitions of parallel of latitude as regards this question is :A: A line that is drawn horizontally around the earth and is parallel to the Prime Meridian.
A circle of latitude can be regarded as a line of latitude that found on Earth, it can be explained as abstract (east–west) small circle which connect all locations around Earth and this is been done at a particular latitude coordinate line.It is drawn horizontally and usually parallel to Prime Meridian.Therefore, option A is correct.
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d.v. hoyt, "an empirical determination of the heating of the earth by the carbon dioxide greenhouse effect", nature 282 (22 november 1979), 388 - 390.
The impact of a higher atmospheric carbon dioxide concentration on Earth's surface temperature has been the subject of numerous theoretical calculations1,2.
Estimates of the rise in Earth's surface temperature brought on by doubling the amount of carbon dioxide in the atmosphere typically fall between 0.7 and 2.9 °C. The temperature rises range from 0.096 to 0.40 °C for a 10% increase in carbon dioxide.All of these conclusions were reached through the use of theoretical models, ranging in complexity from one-dimensional investigations of the planetary radiation budget to three-dimensional general circulation models. Here, a novel solution to this issue is discussed, enabling the calculation of an empirical estimate of the heating of the Earth's surface caused by the greenhouse effect of carbon dioxide.This method suggests that the Earth only warmed by 0.40 °C or less between 1880 and 1970.
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Arrange the atoms in an increasing order of ionization energy. Choose the correct order below.
A.
Hydrogen, Helium, Beryllium, Lithium
B.
Hydrogen, Helium, Lithium, Beryllium
C.
Lithium, Hydrogen, Beryllium, Helium
D.
Lithium, Beryllium, Hydrogen, Helium
Ms. Salis explains to her class that sodium (Na) and chlorine (Cl) atoms bond to make table salt
(NaCl). Which is the best description of table salt? *
A)It is a cell.
B)It is an atom.
C)It is an element.
D)It is a compound
can someone help please !!!!
Answer:
x = 231/90 Th
Explanation:
The vertical columns (top to bottom) on the periodic table are called
Answer:
group
Explanation:
the rows are called periods
groups 1-8
Based on the organization and colors in the periodic table, which two elements do you think are most similar in terms of their properties magnesium (Mg) , barium (Ba) , and gold (Au) ? Explain .
Answer:
Magnesium and barium
Explanation:
They are both Alkaline earth metals. All the alkaline earth metals react with water to produce hydrogen gas and the metal hydroxide, although somewhat less vigorously than the alkali metals.
The organization and colors in the periodic table magnesium and barium are the two element with most of the similar properties because they both belongs to alkaline earth metals.
What are periodic table?
Periodic table are defined as an arrangement of all the elements known to man in accordance with their increasing atomic properties and recurring chemical properties. 118 elements are arranged in periodic table.
Alkaline earth metals are defined as any of the divalent strongly basic metal of group 2 of a periodic table comprising beryllium, magnesium, calcium, barium and radium.
Thus, the organization and colors in the periodic table magnesium and barium are the two element with most of the similar properties because they both belongs to alkaline earth metals.
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Michael’s teacher showed him a sample of charcoal dust and a diamond, as seen in the table below. He was very surprised when she told him both substances were made up of carbon. Why do these two forms of carbon look so different?
Answer:
They are isotopes of each other ,meaning they are made of chemically the same substance but the number of neutrons is different.
Explanation:
What is the mass of 0.78 mol Mg(NO3),? Make sure to round to the correct number of sig figs and to include the unit in your final answer
Answer:
67.08 g
Explanation:
you firts write what u know
then u calculate the molar mass of the salt
then according to the formula mass= number of mols × molar mass you find the mass
m= mass
n= number of mol
M= molar mass i hope this helps