Answer:
A chemical change has occurred
Explanation:
Given reaction expression:
CaCO₃ → CaO + CO₂
The reaction is a decomposition reaction in which a compound is dissociated into simple products.
The reason why the products have different properties than the reactants is because a chemical change has occurred.
A chemical change is accompanied by the formation of a new productSuch new products have different properties compared to the compound that forms them. Therefore, the products and reactants are different chemically due to chemical change that has occurred.The products of the decomposition of calcium carbonate have different properties because a chemical change has occured in the reaction to form new substances.
CHEMICAL CHANGE:A chemical change is a type of change in which new products are formed. The bonds of the reactants are broken and rearranged to form entirely new substances. According to this question, calcium carbonate is a white mineral, which when heated produces carbon dioxide, CO2, and a white powder, CaO as follows: CaCO3 → CO2 + CaOThe products in this reaction are different in their properties from the reactants because a chemical change has caused new substances to be formed.Learn more about chemical change at: https://brainly.com/question/1161517?referrer=searchResults
what do these two changes have in common?
Erosion caused by wind
beating an egg
The Erosion caused by wind and beating an egg both the changes are physical change.
What is erosion?Erosion is defined as a geographical process in which earthen material will blow away and caused by a natural force such as wind or water.
There are mainly four types of erosion
Splash erosionSheet erosionRill erosionGully erosionPhysical change can be defined as a type of change where only the physical properties of the matter changes.
Thus, the Erosion caused by wind and beating an egg both the changes are physical change.
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BUFFERS BUFFERS AND BUFFER CAPACI
INTRODUCTION
LABORATORY SIMULATION
How to calculate the pH of a buffer solution
1) Calculate the pH of a solution prepared by dissolving 2.05 g of sodium acetate, CH3COONa, in 50.0 mL of 0.25 Macetic
acid, CH3COOH(aq). Assume the volume change upon dissolving the sodium acetate is negligible. K₂ of CH3COOH is
1.75 X 10-5.
pH =
The pH of a solution prepared by dissolving 2.05 g of sodium acetate in 50 mL of 0.25 M acetic acid is 5.06.
The above situation is a case of buffer solution.
The pH of a buffer solution can be calculated by the Henderson-Hasselbalch equation,
The equation is as follows:
pH = pKa + log[Salt]/[Acid]
In the above case, sodium acetate(CH3COONa) is the salt and acetic acid(CH3COOH) is the acid.
Putting [Salt] = 0.50 M and [Acid] = 0.25 M and pKa = 4.76 in the equation
pH = 4.76 + log[0.50]/[0.25]
pH = 4.76 + log2
pH = 4.76 + 0.30
pH = 5.06
Thus, the pH of a solution prepared by dissolving 2.05 g of sodium acetate in 50 mL of 0.25 M acetic acid is 5.06.
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Which point would map onto itself after a reflection across the line y = –x?
The point that would map onto itself after a reflection across the line y = –x is (4, –4). The correct option is d.
What is a map?A point would have to be on the line in the first place for it to map onto itself following a reflection over the line.
To calculate the point on the given line, just substitute the x-values of the given points and solve for y.
There are three different x-values: -4, 0, and 4
Substituting these into y = -x
x = -4 ⇒ y = -(-4) = 4 → (-4, 4)
x = 0 ⇒ y = -(0) = 0 → (0, 0)
x = 4 ⇒ y = -(4) = -4 → (4, -4)
Therefore, the correct option is d, (4, –4).
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The question is incomplete. Your most probably complete question is given below:
(–4, –4) (–4, 0) (0, –4) (4, –4)
Two of most unique elements on the periodic table are hydrogen and helium. What makes them so unique and removed from the other groups on the periodic table?
A:Unlike all other elements, hydrogen and helium are gases
B:Unlike all other elements, hydrogen and helium are not considered metals
C:Unlike all other elements, hydrogen and helium only have a maximum of 2 valence electrons
D:Unlike all other elements, hydrogen and helium have very limited properties
What makes hydrogen and helium so unique and removed from the other groups on the periodic table is that unlike all other elements, hydrogen and helium only have a maximum of 2 valence electrons (option C).
What properties of hydrogen and helium makes them unique?Hydrogen and Helium are two elements in the periodic table. They are the lightest elements in the periodic table.
Also, they both exist as gases at room temperature and are the two most common elements in the universe.
However, hydrogen and helium are removed from other groups of the periodic table. Thisis because hydrogen and helium atoms only have two electrons and the outermost energy level is the first energy level, hence, there can only be two valence electrons.
Therefore, what makes hydrogen and helium so unique and removed from the other groups on the periodic table is that unlike all other elements, hydrogen and helium only have a maximum of 2 valence electrons.
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Express each of the following numbers in exponential notation:SHOW YOUR WORK
1) 10,000
2) 0.0001
3) 10,000,000,000
4)0.000 000 000 000 001
5)400,000
Answer:
1 a
2 b
3 c
4 d
5 e
Explanation:
i know is corret
Calculate the number of moles in 5.68 X 10^25 atoms of gold?
Answer:
196.96657 g/m
Explanation:
The molar mass of gold = 196.96657 g/m. The molar mass of gold is defined as the mass of 1 mole of gold atoms - typically specified in grams. Therefore the molar mass of gold is stated in units of grams/mole or g/m. It is also frequently called the Molecular Weight of Gold.
Calculate the energy of an electron at n=2 in butadiene.
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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Calculate the energy per photon (in J) associated with a frequency of 1260 kHz. Submit answer in scientific notation using the format 0.00 x 10^0 (e.g. 0.000123 = 1.23 x 10^-4). Omit units and spaces.
Taking into account the definition of photon and energy of a photon, the energy per photon is 8.3538×10⁻³⁸ J.
Energy of a photonElectromagnetic radiation carries energy, which can be absorbed or emitted. To explain the processes of emission and absortion, Plank and Einstein proposed that the energy of radiation is composed of indivisible units (quanta). In each elemental process only a quantum of light can be emitted or absorbed. Each of these quanta was called a "photon".
The exchanges of energy between matter and radiation take place not continuously, but by discrete and indivisible quantities or quanta of energy. The quantum of energy is proportional to the frequency of radiation.
The relationship between the amount of energy (E) transported by the photon and its frequency (f) is determined by the following expression:
E=h×f
where:
E is the energy of a photon.h is the Planck's constant h. f is the frequency of electromagnetic radiation.Energy per photonIn this case, you know:
h= 6.63*10⁻³⁴ Jsf= 1260 kHz= 1,260,000 Hz= 1.26×10⁶ Hz (being 1 kHz=1000 Hz)Replacing in the definition of energy of a photon:
E= 1.26×10⁶ Hz× 6.63×10⁻³⁴ Js
E= 8.3538×10⁻³⁸ J
Finally, the energy per photon is 8.3538×10⁻³⁸ J.
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Please help me solve this
A student wants to measure the volume of a rock. The student should measure
the volume using?
Answer:
To measure the volume of a large rock, fill a glass measuring cup up to one half with water. Put your large rock in and measure the new water level. Subtract the original half cup volume of water and the difference is the volume or space that your rock takes up.
Answer:
if the rock is small use a measuring cylinder
Explanation:
If 160. g of a radioactive iron (59Fe) is received in the lab today, what percentage of the original is left after 180 days?
If 160.0 g of radioactive iron (59Fe ) is received in the lab today, Then the percentage of the original left after 180 days is 6.25 %.
Radioactive elements are those elements which are made up of those atoms whose nuclei is unstable and emits radiations or undergoes radioactive decay to attain stability or to form stable nuclei.
Given -
t = 180 days
t1/2 = 45 days
So,
n = t = 180 = 4
t1/2 45
Amount of the remaining radioactive iron,
R = R°
2n
where, n = 4
R = 1 = 0.0625
R° 2₄
To calculate percentage of original sample -
percentage of original sample of iron = R x 100
R°
= 0.0625 x 100
= 6.25 %
After 180 days, or 4 half lives, the percentage of radioactive iron remaining is 6.25%.
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Element Q has three isotopes. It is 18.75% -318, 78.26% Q-319, and 2.99% Q-320; The masses of the isotopes are 317.98 amu, 318.98 amu, and 320.026 amu respectively. What is the average atomic mass of the element Q
Answer:
Explanation:
ye
What is the density of a piece of metal that weighs 12 g and has a volume of 500 mL?
Answer:
0.024 g/mL
Explanation:
The denisty of a substance is a ratio comparing its mass per every 1 unit of volume. Therefore, if you have been given a mass in grams and a volume in milliliters, the unit for denisty (in this case) is g/mL.
Density = ? grams / ? mL
Density = 12 g / 500 mL
Density = 0.024 g/ 1 mL = 0.024 g/mL
Which safety equipment is needed when working with materials that car
spatter?
Answer: Required personnel protection equipment (PPE) must be worn at all times
Explanation:
Which of the following accurately describes circuits? Question 11 options: A) In a parallel circuit, there's only one path for the current to travel. B) In a series circuit, the amount of current passing through each part of the circuit may vary. C) In a series circuit, the current can flow through only one path from start to finish. D) In a parallel circuit, the same amount of current flows through each part of the circuit.
In a series circuit, the current can flow through only one path from start to finish.
What is a circuit?The term circuit has to do with the path that current can pass through. Charge flows in a circuit in the direction that current is flowing. Also, resistors in a circuit could be connected in series or in parallel.
In a series connection, the resistors are connected end to end an current flows in one direction.
Thus, the statement that is true is that; In a series circuit, the current can flow through only one path from start to finish.
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Answer: C. In a series circuit, the current can flow through only one path from start to finish.
(just took the test so C is right)
What is 254 nm in meters? Submit answer in scientific notation using the format 0.00x10^0 (e.g. 0.000123 = 1.23x10^-4). Omit units and spaces.
What is the frequency of this irradiation? (Answer from question 1) Submit answer in scientific notation using the format 0.00 x 10^0 (e.g. 0.000123 = 1.23 x 10^-4). Omit units and spaces.
Nanometers is an SI subunit of length equal to 10-⁹ metres. It has a symbol of nm.
The conversion factor of metres to nanometers is as follows:
1 nanometres = 1 × 10-⁹ metres
Hence, 254 nanometers is equivalent to 2.54 × 10-⁷metres.
The frequency of a wave can be calculated using the following formula:
wavelength = wave velocity/frequency
frequency = 3 × 10⁸ ÷ 2.54 × 10-⁷
Frequency = 1.18 × 10¹⁵Hz
Therefore;
254nm is equivalent to 2.54 × 10-⁷metres. The frequency of a radiation that has a wavelength of 254nm is 1.18 × 10¹⁵HzLearn more about frequency and wavelength at: https://brainly.com/question/3639648
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Write a balanced chemical equation based on the following description:
gaseous nitrogen and hydrogen react to form gaseous ammonia
The balanced chemical equation of a reaction between gaseous nitrogen and hydrogen to form gaseous ammonia is as follows; N₂ + 3H₂ → 2NH₃.
What is a balanced chemical equation?A chemical equation is a symbolic representation of a chemical reaction where reactants are represented on the left, and products on the right.
A chemical reaction is said to be balanced, in accordance with the law of conservation of matter, when the number of moles of each atom of elements on both sides of the equation are the same.
According to this question, gaseous nitrogen and hydrogen react to form gaseous ammonia. The balanced chemical equation is as follows:
N₂ + 3H₂ → 2NH₃
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The atomic mass of an element on the periodic table is based on which of the following? Explain why or why not for each answer.
a. The number of protons
b. The average atomic mass of all isotopes
c. The average number of electrons and neutrons from all isotopes
d. The number of neutrons
The correct answer to the given question is b) The average atomic mass of all isotopes is what an element’s atomic mass is based on in the periodic table.
An element has many isotopic masses, in which elements have same number of protons but different number of neutrons. An element in the periodic table has the average of all the isotopes. Atomic mass is the sum of protons and neutrons, without the involvement of electrons. For example, Chlorine has 2 isotopes Chlorine-35 having atomic mass 35 and Chlorine- 37 having atomic mass 37. The element Chlorine which is found in the periodic table has atomic mass 35.5 u, based on the average atomic masses and their relative abundance.
Therefore, atomic mass of an element on the periodic table is the average of their atomic mass of all isotopes.
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Which factor affects the temperature of ocean water?
depth
salinity
number of organisms
amount of dissolved gases
The factor affecting the temperature of ocean water among the given options is depth of the ocean.
The temperature of ocean water varies with the depth. Ocean is divided into the three layers depending on the depth. In the ocean, solar energy reflects in upper surface and rapidly gets absorbed with the depth. Upper layer has depth of around 500 m and temperature 20°C - 25°C.
Second layer is thermocline layer with relatively low temperature of water. It indicates that, the deeper you go into the ocean, less sunlight is there. Therefore, deeper oceans are colder.
Deep ocean water is around 90% of the volume of oceans. It has uniform temperature of around 0-3°C.
Temperature and depth are related in such a way that the temperature decreases when the depth increase.
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Answer:
It is A. DepthExplanation:
Hope this helps
Question 5
The process by which a gas condenses is referred to as
exothermic.
endothermic.
ectodermic.
exotic.
What is the pH of an aqueous solution with a hydrogen ion concentration of [H+]=7.6×10−9 M?
The pH of an aqueous solution with a hydrogen ion is 8.11
pH is the quantitative measure of the acidity or basicity of aqueous or other liquid solutions
Here given data is concentration of [H⁺]=7.6×10⁻⁹ M
We have to find pH=?
Then, pH = -log(conc)
Then pH = -log(7.6×10⁻⁹)
pH = 8.11
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4. Study the flow diagram below the answer the questions that follow C Mg (a) Write the chemical formulae of products () A B (b) Write the equations for the reactions that form products (1) (11) C...... D and E
Answer:
where is flow diagram.....
.........
Periodic trends answer key chemistry 10th grade
Trends in modern periodic table are:
variation of valency, atomic size , metallic properties and electronegativity
Valency - number of valence electrons . Elements of each group have same number of valence electrons. So, they have the same valency.
Atomic size- It is distance from the centre of the nucleus to the valence shell of the atom.
Along the period – Atomic radius decreases as effective nuclear charge increases . It pulls valence electrons closer to the nucleusDown the group – Atomic radius increases because new shells are added , thus the distance between nucleus and valence electrons increases.Metallic properties -
Along the period – Metallic character decreases because tendency to lose valence electrons decreases due to the increasing nuclear charge.Down the group – As the distance between nucleus and outermost electron increases, nuclear pull decreases. This increases the tendency of an atom to lose valence electrons, thus metallic character increases.Electronegativity-
Along the period – Electronegativity increases as the tendency to gain electrons in valence shell increases due to increasing nuclear charge. Down the group – Since distance between the nucleus and valence shell increases, nuclear pull decreases. This decreases tendency of atom to gain an electron, thus electronegativity decreases.So we can conclude that periodic trends are specific patterns which are present in the periodic table, that illustrate different aspects of a certain element
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Density measurements can be used to analyze mixtures. For example, the density of solid sand (without air spaces) is about 2.84 g/mL. The density of gold is 19.3 g/mL. If a 1.00 kg sample of sand containing some gold has a density of 3.10 g/mL (without air spaces), what is the percentage of gold in the sample?
The percentage of gold in the sample if a 1.00 kg sample of sand containing some gold has a density of 3.10 g/mL is 9.83%.
Let S be the solid sandy mass which is inside the blend
Let G be the gold mass in such a blend
We have to find the percent G by mass
Mixture density can be calculated as
= total blend mass / total blend volume
= 3.10 g/mL
Mixture sum is
S + G = 1 Kg. = 1000g
Complete mixing volume = sand volume + gold volume
Complete mixing volume can be calculated as
=[tex](\frac{sand mass}{sand density} ) + (\frac{gold mass }{gold density} )[/tex]
Total mixture volume:-
[tex]= (\frac{S}{2.84} ) + (\frac{G}{19.3} )\\\\= \frac{(19.3 S + 2.84 G)}{54.812 mL} \\\\Mixture Density = \frac{mass mixture}{mixture volume}\\ \\= 3.10 \frac{g}{mL}[/tex]
⇒ [tex]3.10 = \frac{1000 g}{ \frac{(19.3 S + 2.84 G)}{54.812 mL}}[/tex]
[tex]19.3 S + 2.84 G = 17681\\\\When S+ G = 1000 g\\\\Solving equation:[/tex]
⇒[tex]19.3 S + 2.84 G = 17681[/tex]
∴ [tex]S + G = 1000 g[/tex]
⇒ 19.3 S + 2.84 = 17681
⇒ -2.84 S - 2.84 = -2840
________________________
⇒ 16.46 S = 14841
⇒ S = 901.7g Sand
Given,
⇒ S + G = 1000
⇒ G = 1000 - 901.7 g
⇒ G = 98.3 g Gold
Percentage of gold in the solution is
(98.3/1000) × 100 = 9.83%
Thus, we concluded that the percentage of gold in the sample if a 1.00 kg sample of sand containing some gold has a density of 3.10 g/mL is 9.83%.
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What number of hydrogen atoms is in 0.48 mol of Prevacid?
There are 4 * 10^24 atoms of hydrogen in 0.48 moles of prevacid.
What is prevacid?The drug prevacid is used as an antacid. What is does is to reduce the amount of acid that could be produced in the stomach of a person. As a result of this, the drug prevacid is able to relieve a person of heartburn and stomach ulcer.
Thus time, we want to obtain the number of hydrogen atoms that id present in one 0.48 moles of the drug prevacid.
We have that there are 14 hydrogen atoms in prevacid. Thus;
14 * 0.48 * 6.02 * 10^23 = 4 * 10^24 atoms of hydrogen.
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What Is The hypothesis for,What Effect Does Using Plant Food Have On Plant Growth?
Answer: If the amount of fertilizer applied to plants is increased, then plant growth (height) will increase. As the amount of fertilizer increases the plant growth increases.
Explanation: It's correct
During a UV-Visible spectroscopy experiment, a student notes a wavelength peak measurement at 280 nm. What region of the electromagnetic spectrum was this peak observed?
If during a spectroscopy experiment a student notes a wavelength peak measurement at 280 nm, then the region of the electromagnetic spectrum observed is the UV region.
What is the electromagnetic spectrum?The electromagnetic spectrum refers to all types of wavelengths that radiation can emit as light, which involves both visible light and also ultraviolet (UV) radiation.
In conclusion, if during a spectroscopy experiment a student notes a wavelength peak measurement at 280 nm, the region of the electromagnetic spectrum observed is the UV region.
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PLEASE HELP ASAP!!
An iron refinery produces an iron ingot weighing 150.0 lb. (An ingot is a piece of relatively pure metal that is cast in a block.) If the iron is drawn into wire whose diameter is 7.50 mm, how many feet of iron can be obtained from the ingot? The density of iron is 7.87 g/mL. The cost of iron is $109 per metric ton. How much is this wire worth?
A tortoise moves at a speed of 454 cm/min. How fast is the tortoise in mph?
Hint: there are 5280 feet in 1 mile
A) 0.17 mph
B) 0.34 mph
C) 17 mph
D) 0.0017 mph
Answer:
AFor a hydrogen atom, calculate the energy of the photon that would be emitted for the orbital transition of n(initial) = 5 to n(final) = 3. The Rydberg constant is 1.09678 x 10⁷ m⁻¹.
The energy of the photon is 1.5 * 10^-19 J
What is the Bohr model?According to the Bohr model of the atom, the atom is arranged in energy levels. It is possible for an electron to transition from a lower to a higher energy level by the gain of energy. The energy that is gained must be equal to the difference in energy between the lower and the higher energy levels of the atom.
No we know that we could use the Rydberg formula to obtain the wavelength of the photon that is emitted when an electron moves from a higher to a lower energy level with the emission of the energy that was taken in.
Thus;
1/λ = RH (1/n^2 final – 1/n^2 initial)
RH = 1.09678 x 10⁷ m⁻¹
n final = 3
n initial = 5
1/λ =1.09678 x 10⁷ (1/3^2 – 1/5^2)
1/λ = 1.09678 x 10⁷ (0.11 – 0.04)
λ = 1302 nm
E = hc/ λ
E = 6.6 * 10^-34 * 3 * 10^8/1302 * 10^-9
E = 1.5 * 10^-19 J
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