Answer:
false
Explanation:
jk true
Burning is a type of_________reaction.
O replacement
O decomposition
O synthesis
O combustion
Answer:
Combustion
Explanation:
Happy Halloween!
A scientist wants to prove that certain chemicals in cosmetics are likely to cause harm to developing fetuses, when used by a pregnant woman. What is the most likely limitation she will face in her scientific design? PLEASE HURRY!!
Answer:
D. Limitations due to ethical concerns about experimental subjects.
Explanation:
Answer:
A
Explanation:
(its my friend)
• True False estion 2 (1 point) Water and ice are made from the same molecule H2O True False
Answer:
true i think
Explanation:
there about 5000 elements, which combine to form the vast number of diffrent substances in the world around us
Answer: false 100
Explanation:
if this is the true or false test here
With some manipulation, the Rydberg equation can be rewritten in the form
E=constant×(1nf2−1ni2)
which allows you to calculate the energy of the emitted light. Express this constant in terms of the constants h, c, and RH using relationships between wavelength and energy as well as the Rydberg equation from the introduction.
Express the constant in terms of h and c, and RH.
Please help me with this question?
Answer:
attached below is the detailed solution
answer : value of constant = 2.18 * 10^-18 J
Explanation:
Express the constant in terms of h and c and RH
attached below is the detailed solution
Constant = [tex]h_{C} R_{H}[/tex]
= ( 6.626 * 10^-34 ) * ( 3 * 10^8 ) * ( 1.097 * 10^7 )
= 2.18 * 10^-18 J
The Planck equation and the light speed allow us to find the results for the transformation of the Rydberg equation are:
[tex]E = A ( \frac{1}{n_1^2}\frac{x}{y} - \frac{1}{n_2^2} )\\A= R_H \ h \ c \\A = 2.18 \ 10^{-18} j[/tex]
The Rydberg equation is an empirical expression that explains the wavelength of the emissions.
[tex]\frac{1}{\lambda } = R_H ( \frac{1}{n_1^2} - \frac{1}{n_2^2} )[/tex]
Where λ is the wavelength of the emitted radiation, is the Rydberg constant, n₁ and n₂ are integers with n₁ <n₂
It is asked to write the Rydberg equation for the energy.
Let's use the Planck relation.
E = h f
The light speed is related to the wavelength and frequency of radiation.
c = λ f
Where E is the energy, h the Planck constant, c the speed of light, λ the wavelength and f the frequency.
Let's substitute.
E = [tex]\frac{hc}{\lambda}[/tex]
[tex]\frac{1}{\lambda} = \frac{E}{hc}[/tex]
Let's substitute in the Rydberg equation.
[tex]\frac{E}{hc} = R_H ( \frac{1}{n_1^2} - \frac{1}{n_2^2}) \\E = R_H \ h \ c \ ( \frac{1}{n_1^2} - \frac{1}{n_2^2} )[/tex]
We can write is an constant of the form.
A = [tex]R_H h c[/tex]
The value of the constant is :
A = 1,097 10⁷ 6,626 10⁻³⁴ 3 10⁸
A = 2.18 10⁻¹⁸ J
In conclusion, using the Planck equation and the light speed we can find the results for the transformation of the Rydberg equation are
[tex]E = A ( \frac{1}{n_1^2} - \frac{1}{n_2^2} )\\ A = R_H h c\\[/tex]
A = 2.18 10⁻¹⁸ J
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Select the correct answer.
In which situation is no work considered to be done by a force?
A.
when the angle between the force and displacement is 180°
B.
when the angle between the force and displacement is 90°
C.
when the angle between the force and displacement is 45°
D.
when the angle between the force and displacement is 0°
Answer:
Explanation:
when the angle between the force and displacement is 0
In which ocean zone would photosynthetic organisms be found?
Answer:
Photic Zone
Explanation:
The photic zone is the uppermost layer of the sea that recieves sunlight allowing phytoplankton to perform photosynthesis.
HELPPP PLEASEEE!!! calculate the energy of radiation with a wavelength of 432 nm
at what temperature does a solid turn into a liquid
Answer:
0°C
Hope this helps Do mark as brainliestAnswer:
a little over 0 degrease cel
Explanation:
Sodium + oxygen
What colour is the flame produces
Answer:
Orange
Explanation:
I used google my b
Answer:
ORANGE
explanation:
Small pieces of sodium burn in air with often little more than an orange glow. Using larger amounts of sodium or burning it in oxygen gives a strong orange flame.
The overall reaction in a commercial heat pack can be represented as How much heat is released when 4.40 moles of iron are reacted with excess ? Heat = kJ How much heat is released when 1.00 mole of is produced? Heat = kJ How much heat is released when 1.60 g iron is reacted with excess ? Heat = kJ How much heat is released when 11.8 g and 1.20 g are reacted? Heat = kJ
Answer:
Explanation:
The overall equation for this reaction can be represented as:[tex]4 Fe(s) + 3 O_{2(g) } \to 2Fe_2O_{3(s)} \ \ \ \ \Delta H = -1652 \ kJ[/tex]
The first question says:
How much heat is released when 4.40 moles of iron is reacted with excess O₂?
Suppose 1652 kJ of heat is being emitted into the surroundings when four(4) moles of Fe reacted with O₂, therefore;
4.40 moles of Fe reacts with:
[tex]=\dfrac{4.40 \ moles \times 1652 \ kJ}{4 \ moles}[/tex]
= 1817.2 kJ of heat will be produced.
The second question says:
How much heat is released when 1.00 mole of [tex]Fe_2O_3[/tex] is produced?
Given that 1652 kJ of heat is being emitted into the surroundings when two(2) moles of [tex]Fe_2O_3[/tex] is produced, therefore;
1.00 moles of [tex]Fe_2O_3[/tex] reacts with:
[tex]=\dfrac{1.00 \ moles \times 1652 \ kJ}{2 \ moles}[/tex]
= 826 kJ of heat will be produced.
To the third question; we have:
How much heat is released when 1.60 g iron is reacted with excess O₂?
We need to find the number of moles of iron first.
We know that number of moles = mass/molar mass
Thus, the molar mass of iron = 55.8 g/mol
number of moles of iron = (1.60g) / (55.8 g/mol)
number of moles of iron = 0.02867 mol
Thus; [tex]\dfrac{0.02867\ mol \times 1652 \ kJ }{4 \ mol}[/tex]
= 11.84 kJ of heat is released.
The last question says:
How much heat is released when 11.8 g Fe and 1.20 g O₂ are reacted?
Again;
the number of moles of Fe = (11.8g) / (55.8 g/mol) = 0.2114 mole of Fe
Thus; [tex]\dfrac{0.2114\ mol \times 1652 \ kJ }{4 \ mol}[/tex]
= 87.31 kJ of heat is released.
On the other hand,
the number of moles of O₂ = (1.20g) / (32 g/mol) = 0.0375 mol of O₂
Thus; [tex]\dfrac{0.0375\ mol \times 1652 \ kJ }{3 \ mol}[/tex]
= 20.65 kJ of heat is released
Therefore, when these two(2) reactants reacted with each other, it is just the smaller amount of heat that would be released because oxygen tends to be the limiting reactant.
How many electrons does each lithium atom provide to the voltaic cell?
A. 1
B. 2
C. 3
D. 4
Answer:
c. 3 electrons
Explanation: for the element of LITHIUM, you already know that the atomic number tells you the number of electrons. That means there are 3 electrons in a lithium atom.
Identify the law that explains the following observation:
Nitrogen Dioxide can be formed by reacting 14 grams of
nitrogen with 32 grams of oxygen.
Answer:
Proust's law of definite proportion
Explanation:
The law of constant proportion states that the components elements of a given chemical compound combine with each other in a fixed mass ratio when the compound is produced by any given process
Therefore, from the question, the chemical formula for Nitrogen Dioxide is NO₂, where the molar mass of nitrogen, N = 14
The molar mass of oxygen, O = 16
Given that one molecule of NO₂, contains one atom of nitrogen and two atoms of oxygen, one mole of NO₂ will contain 14 grams of nitrogen and 32 grams of oxygen, according to Proust's law of definite proportion.
Question 2 of 11
Which of these are part of a scientific way of gathering information?
A. Fairy tales
B. Religious beliefs
C. Investigations
D. Opinions
SUBMIT
Answer:
C
Explanation:
the rest arent scientific
Answer:
C. Investigations
Explanation:
Test approved
Which of the following is an irreversible physical change?
a) melting a piece of lead
b) sharpening a pencil
c) dissolving sugar into water
d) boiling water
Answer:
b) sharpening a pencil
Explanation:
If you melt lead, boil water, or dissolve sugar in water, you can return all of them back to their original state. If you sharpen a pencil, you can't reattach the shavings as they were originally.
You may put all of them back to their original states by melting lead, heating water to a boil, or dissolving sugar in water. You cannot rejoin the shavings from a sharpened pencil in their original position. Thus, option B is correct.
What is irreversible physical change?When something changes physically but not chemically, it has undergone an irreversible physical alteration that cannot be reversed.
Sharpening a pencil is a perfect example of an irreversible physical change. The wood turns to dust when you sharpen it. Just in a different shape, it is still wood. That wood dust cannot be transformed back into a pencil.
You cannot put a piece of paper back together the same way it was before you tore it if you tear it into tiny pieces.
An irreversible alteration is one that cannot be undone or that cannot be returned to its original state, such as when milk turns into curd, iron turns rusty, paper burns, food is cooked, etc.
Therefore, sharpening a pencil is an irreversible physical change
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After stirring salt in a container of water, the salt will dissolve. When adding more salt, eventually the salt will not dissolve. Which of the following refers to a substance that can no longer dissolve in a liquid? *
A. boiling point
B. melting point
C. saturation point
D. all of these
Answer: C. Saturation point
Explanation:
I’ll give the Brainliest, you also need to explain how the answer you got is correct.
Choose the best description of a neap tide.
A. Neap tides produce during the highest tides of the month.
B. Neap tides happen during winter and summer.
C. Neap tides could be described as low high tides and high low tides.
D. A neap tide is the period halfway between tides when the tide changes direction.
Thank you!
Answer:
D. A neap tide is the period halfway between tides when the tide changes direction. (correction) Answer : C
Explanation:
Process of elimination can be used. First off, A is incorrect because neap tides have the smallest tidal range ; spring tides would fit this choice. B is incorrect since neap tides are specific to the first, and third quarter moons when the sun and moon are right angles. C is wrong because it is the other way around since high tides are a little higher than average and low tides are a little lower than average (correction) this is correct since higher low tides and lower high tides are closer together and have a smaller tidal range than standard tides(spring tides) with higher high tides, and lower low tides. D is correct because they occur halfway between the spring tides (correction): incorrect since a neap tides occur around a week(7 days) after a spring tide(moderate tides). There is no evidence this is true.
There are three patterns: diurnal(one high and low tides a day), semidiurnal(two high and low tides a day), and mixed(two high and low tides a day of different lengths).
The spring and neap tides are the types of tides involved with the low and high tides.
Which ecosystem is the least stable?
Answer:
tundra bc it has barley any food source and has vary little inhabitants
Explanation:
Answer:
a patch of lichens on bare rock
Help me answer the question please I don’t get it this is earth science not chemistry.
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A metal block, 2.0cm x 2.5cm x 3.0cm, has a mass of 40.5g. What is the density of the sample? What type of metal is the metal block composed of?
Aluminum - 2.699
Copper - 8.92
Iron - 7.874
Lead - 11.43
Nickel - 8.908
Tin - 7.265
Zinc - 7.14
Answer:
The block is made up of aluminum.
density = 2.7 g/cm³
Explanation:
Given data:
Dimension of metal block = 2.0 cm×2.5 cm× 3.0 cm
Mass of block = 40.05 g
Density of block = ?
Which metal is this = ?
Solution:
Density:
Density is equal to the mass of substance divided by its volume.
The symbol used for density is called rho. It is represented by ρ. However letter D can also be used to represent the density.
Units:
SI unit of density is Kg/m3.
Other units are given below,
g/cm3, g/mL , kg/L
Formula:
D=m/v
D= density
m=mass
V=volume
Volume of block = 2.0 cm×2.5 cm× 3.0 cm = 15 cm³
d = m/v
d = 40.5 g/ 15 cm³
d = 2.7 g/cm³
The block is made up of aluminum.
Sodium, an alkali metal, and chlorine, a halogen, are both in Period 3 of the periodic table. Which element has
a higher ionization energy? Explain your answer.
Answer:
Chlorine has higher ionization energy.
Explanation:
Sodium is present on left side of periodic table in period 3 while chlorine is present on right side of periodic table in period 3.
As we move from left to right across the periodic table the number of valance electrons in an atom increase. The atomic size tend to decrease in same period of periodic table because the electrons are added with in the same shell. When the electron are added, at the same time protons are also added in the nucleus. The positive charge is going to increase and this charge is greater in effect than the charge of electrons. This effect lead to the greater nuclear attraction. The electrons are pull towards the nucleus and valance shell get closer to the nucleus. As a result of this greater nuclear attraction atomic radius decreases and ionization energy increases because it is very difficult to remove the electron from atom and more energy is required. Thus chlorine have higher ionization energy as compared to the sodium.
Explain how the igneous rock granite forms. Then tell how the granite might become the sedimentary rock sandstone and then the metamorphic rock quartzite.
Answer:
There are three main types of rocks: sedimentary, igneous, and metamorphic. Each of these rocks are formed by physical changes—such as melting, cooling, eroding, compacting, or deforming—that are part of the rock cycle. Sedimentary Rocks Sedimentary rocks are formed from pieces of other existing rock or organic material. There are three different types of sedimentary rocks: clastic, organic (biological), and chemical. Clastic sedimentary rocks, like sandstone, form from clasts, or pieces of other rock. Organic sedimentary rocks, like coal, form from hard, biological materials like plants, shells, and bones that are compressed into rock. The formation of clastic and organic rocks begins with the weathering, or breaking down, of the exposed rock into small fragments. Through the process of erosion, these fragments are removed from their source and transported by wind, water, ice, or biological activity to a new location. Once the sediment settles somewhere, and enough of it collects, the lowest layers become compacted so tightly that they form solid rock. Chemical sedimentary rocks, like limestone, halite, and flint, form from chemical precipitation. A chemical precipitate is a chemical compound—for instance, calcium carbonate, salt, and silica—that forms when the solution it is dissolved in, usually water, evaporates and leaves the compound behind. This occurs as water travels through Earth’s crust, weathering the rock and dissolving some of its minerals, transporting it elsewhere. These dissolved minerals are precipitated when the water evaporates. Metamorphic Rocks Metamorphic rocks are rocks that have been changed from their original form by immense heat or pressure. Metamorphic rocks have two classes: foliated and nonfoliated. When a rock with flat or elongated minerals is put under immense pressure, the minerals line up in layers, creating foliation. Foliation is the aligning of elongated or platy minerals, like hornblende or mica, perpendicular to the direction of pressure that is applied. An example of this transformation can be seen with granite, an igneous rock. Granite contains long and platy minerals that are not initially aligned, but when enough pressure is added, those minerals shift to all point in the same direction while getting squeezed into flat sheets. When granite undergoes this process, like at a tectonic plate boundary, it turns into gneiss (pronounced “nice”). Nonfoliated rocks are formed the same way, but they do not contain the minerals that tend to line up under pressure and thus do not have the layered appearance of foliated rocks. Sedimentary rocks like bituminous coal, limestone, and sandstone, given enough heat and pressure, can turn into nonfoliated metamorphic rocks like anthracite coal, marble, and quartzite. Nonfoliated rocks can also form by metamorphism, which happens when magma comes in contact with the surrounding rock. Igneous Rocks Igneous rocks (derived from the Latin word for fire) are formed when molten hot material cools and solidifies. Igneous rocks can also be made a couple of different ways. When they are formed inside of the earth, they are called intrusive, or plutonic, igneous rocks. If they are formed outside or on top of Earth’s crust, they are called extrusive, or volcanic, igneous rocks. Granite and diorite are examples of common intrusive rocks. They have a coarse texture with large mineral grains, indicating that they spent thousands or millions of years cooling down inside the earth, a time course that allowed large mineral crystals to grow.
Alternatively, rocks like basalt and obsidian have very small grains and a relatively fine texture. This happens because when magma erupts into lava, it cools more quickly than it would if it stayed inside the earth, giving crystals less time to form. Obsidian cools into volcanic glass so quickly when ejected that the grains are impossible to see with the naked eye. Extrusive igneous rocks can also have a vesicular, or “holey” texture. This happens when the ejected magma still has gases inside of it so when it cools, the gas bubbles are trapped and end up giving the rock a bubbly texture. An example of this would be pumice.
Explanation:
oh and also nice profile pic :P
The momentum of a 23 000 kg truck traveling eastward with a velocity of 50.0 m/s is kom/s
Answer:
Explanation:
I'm not sure what you mean by the units. The answer using kg and ms is 23000 * 50 = 1150000 kg m/s
which of these elements is most likely to be magnesium the most metallic of all samples?
Answer:
B
Explanation:
Just did it on usa test prep
The element which is most likely to be magnesium is the element with the electronic configuration same as magnesium.
What is an element?It is defined as a substance which cannot be broken down further into any other substance. Each element is made up of its own type of atom. Due to this reason all elements are different from one another.
Elements can be classified as metals and non-metals. Metals are shiny and conduct electricity and are all solids at room temperature except mercury. Non-metals do not conduct electricity and are mostly gases at room temperature except carbon and sulfur.
The number of protons in the nucleus is the defining property of an element and is related to the atomic number.All atoms with same atomic number are atoms of same element.
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Which of the following is most likely NOT a chemical reaction?
(A)
A white powder and a clear liquid mix and the beaker holding the mixture gets cool to the touch
(B)
A white solid and a clear liquid mix and produce a bright orange, bubbling substance
(C)
A pan containing a clear liquid is place on a hot stove and begins to bubble after a few minutes.
(D)
A blue liquid and a green solid mix and produce a purple paste
Answer:
B is the correct answer because bubbling is a sign of chemical reaction and production of a new substance
Which two types of information are found in an element's box in the periodic
table?
A. Atomic number
B. Chemical symbol
O C. Chemical formula
O D. Atomic structure
( TWO ANSWERS)
The information we can obtain for an element from periodic table is its atomic number and chemical symbol. Thus option A and B are correct.
What is atomic number?Atomic number of an element is the number of protons of the element. For a neutral atom the number of electrons is equal to the number of protons.
There are 118 elements in the modern periodic table and they are classified into different group and periods. Elements of same number of valence electrons and similar physical and chemical properties are classified into one group.
There are 18 groups and 7 period in the periodic table. Each classification is based on their atomic number. Chemical symbols are used to represent the elements and they can be easily identified by the symbols.
For example, hydrogen have the chemical symbol H and oxygen with O and carbon with C. etc. Similarly we can get mass number of elements from periodic table. Thus option A and B are correct.
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NEED HELP PLEASE
Part A:
In your own words, describe the process of a physical change.
Part B:
What is the difference between a physical change and a chemical change? Give an example of each.
Answer:
Part A:
A physical change is a change of a substance from one form to another without changing its composition.
Part B:
A physical change is a change of a substance from one form to another without changing its composition. Example: A balloon deflating into its original form.
A chemical change occurs, one substance combines with another substance to make something completely new. Example: Making and baking a cake.
Which describes the motion of the car as shown by the graph?
A) travels at a constant speed
B) not moving
C) changing directions
D) speeding up
Which three types of electromagnetic waves have longer wavelengths than the waves that make up visible light?
O radio waves, gamma rays, X-rays
O gamma rays, infrared light, X-rays
O microwaves, radio waves, infrared light
infrared light, ultraviolet light, microwaves
Answer:
O microwaves, radio waves, infrared light
Explanation:
Answer: C. microwaves, radio waves, infrared light
Explanation: C. Microwaves, Radio Waves, Infrared light
I hate chemistry please help
Answer:
Love it because Love it
Explanation: