Answer:
D. all of these are chemical changes
1
Select the correct answer.
Which statement about the relationship between laws, hypotheses, and theories is true?
A.
Laws that remain true over an extended period of time are considered theories.
B.
A theory that holds true for a long time is considered a law.
C.
If a law is not contradicted after a lot of testing, it may be considered a hypothesis.
D.
If a hypothesis is not contradicted after a lot of testing, it may be considered a law.
Answer:
the answer is D
Explanation:
explain why division by zero is undefined
Answer:
Division by zero is undefined because there is no other number to divide it by.
Explanation:
Unlike 2/2, 2/0 doesn't have anything to divide the 2 by which makes it undefined and impossible to solve.
The division by zero is undefined, because whatever response we may give, we will then have to concur that the answer times 0 = 1, which is illogical because anything multiplied by zero is zero.
Why division by zero is undefined ?Since any attempt at definition results in a contradiction, the outcome of a division by zero cannot be defined. a=r*b. r*0=a. (1) (1) But because r*0=0 for all r, there is no solution to the equation unless a=0 (1).
Again, mathematicians have left zero divided by zero as an open problem because they are both equally valid and, to be honest, neither of them is consistent with the rest of mathematics.
Mathematically, it is impossible to divide a number by zero, just as in this illustration. Or, at the very least, there isn't currently a means to do that. Numerous attempts have been made to figure out how to divide by zero, as mathematicians are constantly looking for solutions to intriguing mathematical issues.
Thus, The division by zero is undefined, because whatever response we may give, we will then have to concur that the answer times 0 = 1.
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a nucleus with 4 protons has a positive charge of _____ PLEASE LET ME KNOW
Answer:
if were talking about berylium then the answer should be 2 because it wants to move 2 spaces back (losing electrons) to become a nobel gas so the answer is 2+
Explanation:
it has 2 valence electrons YW :)
A nucleus with 4 protons has a positive charge of +2.
What are Protons?Protons may be defined as the type of sub-atomic particles that are present in the nucleus of an atom along with the neutrons. These sub-atomic particles possess a positive charge in nature. It may be thought that protons are discovered by Ernest Rutherford.
Beryllium has a nucleus with 4 protons, which means that it has an atomic number of 4. This element belongs to the alkaline earth metals in group 2. Beryllium has the capability to lose two electrons in order to attain a noble gas configuration and occupy stability. It has an electronic configuration [tex]1s^2, 2s^2[/tex]. So, in order to make it octet fulfilled, it loses two electrons and becomes positively charged.
Therefore, a nucleus with 4 protons has a positive charge of +2.
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3. Calculate each of the following:
a) kg of 4.6x1021 molecules of nitrogen dioxide
b) moles of chlorine atoms in 0.615 g of C2H4Cl2
c) number of hydride ions in 5.82 g of strontium hydride
Answer:
the answers are at the very bottom of each picture
Explanation:
i really hope this helps you:)
A state of dynamic equilibrium, Ag2CO3(s) 2Ag^+(aq) + CO3^2-, exists in solution.
What shift occurs in the equilibrium if HCl (aq) is added to the system? Explain please
Answer:
The equilibrium will shift to the right producing more Ag⁺ and CO₃²⁻
Explanation:
In the equilibrium:
Ag₂CO₃(s) ⇄ 2Ag⁺(aq) + CO₃²⁻(aq)
The change in concentration of Ag⁺ or CO₃²⁻ will shift the equilibrium
The addition of HCl(aq) (Dissociates in H⁺ and Cl⁻ ions) produce the formation of AgCl. The reaction is:
Ag⁺(aq) + Cl⁻(aq) ⇄ AgCl(s)
That means the addition of HCl decrease concentration of Ag⁺.
Based on LeChatelier's principle: As the Ag⁺ decreases, the equilibrium will decrease amount of Ag₂CO₃ producing more Ag⁺ and CO₃²⁻. That is:
The equilibrium will shift to the right producing more Ag⁺ and CO₃²⁻Over the course of many years, a rural farm town becomes more urban. Which of the following will most likely happen in the town as a result of this urbanization?
Answer:
Explanation:
Rivers may be contaminated by sewage.
I do hope I helped you! :)
The flask contains 10.0 mL of HCl and a few drops of phenolphthalein indicator. The buret contains 0.160 M NaOH. It requires 18.2 mL of the NaOH solution to reach the end point of the titration. A buret filled with a titrant is held above a graduated cylinder containing an analyte solution. What is the initial concentration of HCl
Answer:
Approximately [tex]0.291\; \rm M[/tex] (rounded to two significant figures.)
Explanation:
The unit of concentration [tex]\rm M[/tex] is the same as [tex]\rm mol \cdot L^{-1}[/tex] (moles per liter.) On the other hand, the volume of both the [tex]\rm NaOH[/tex] solution and the original [tex]\rm HCl[/tex] solution here are in milliliters. Convert these two volumes to liters:
[tex]V(\mathrm{NaOH}) = 18.2\; \rm mL = 18.2 \times 10^{-3}\; \rm L = 0.0182\; \rm L[/tex].[tex]V(\text{$\mathrm{HCl}$, original}) = 10.0\; \rm mL = 10.0\times 10^{-3}\; \rm L = 0.0100\; \rm L[/tex].Calculate the number of moles of [tex]\rm NaOH[/tex] in that [tex]0.0182\; \rm L[/tex] of [tex]0.160\; \rm M[/tex] solution:
[tex]\begin{aligned} n(\mathrm{NaOH}) &= c(\mathrm{NaOH})\cdot V(\mathrm{NaOH})\\ &= 0.160\; \rm mol \cdot L^{-1} \times 0.0182\; \rm L \approx 0.00291\; \rm mol\end{aligned}[/tex].
[tex]\rm HCl[/tex] reacts with [tex]\rm NaOH[/tex] at a one-to-one ratio:
[tex]\rm HCl\; (aq) + NaOH\; (aq) \to NaCl\; (aq) + H_2O\; (l)[/tex].
Coefficient ratio:
[tex]\displaystyle \frac{n(\mathrm{HCl})}{n(\mathrm{NaOH})} = 1[/tex].
In other words, one mole of [tex]\rm NaOH[/tex] would neutralize exactly one mole of [tex]\rm HCl[/tex]. In this titration, [tex]0.291\; \rm mol[/tex] of [tex]\rm NaOH\![/tex] was required. Therefore, the same amount of [tex]\rm HC[/tex] should be present in the original solution:
[tex]\begin{aligned}&n(\text{$\mathrm{HCl}$, original})\\ &= n(\mathrm{NaOH})\cdot \frac{n(\mathrm{HCl})}{n(\mathrm{NaOH})} \\ &\approx 0.00291\; \rm mol \times 1 = 0.00291\; \rm mol\end{aligned}[/tex].
Calculate the concentration of the original [tex]\rm HCl[/tex] solution:
[tex]\displaystyle c(\text{$\mathrm{HCl}$, original}) = \frac{n(\text{$\mathrm{HCl}$, original})}{V(\text{$\mathrm{HCl}$, original})} \approx \frac{0.00291\; \rm mol}{0.0100\; \rm L} \approx 0.291\; \rm M[/tex].
In a compound the elements are _____ together, whereas in a mixture the substances are blended together.
Answer:
bonded
Explanation:
Compounds are two elements bonded together.
A mixture is multiple substances blended together. The substances aren't bonded together and can easily be extracted from each other.
find the R when p=6000,T=3 yrs 6 month ,I=1155
R= 1155×100/6000×3/12
R= 1155×2/3
R=770Be sure to answer all parts. Calculate the mass of each product formed when 70.76 g of diborane (B2H6) reacts with excess water: B2H6(g) + H2O(l) → H3BO3(s) + H2(g) [unbalanced] Mass of H3BO3: g Mass of H2: g
Answer:
A. 313.37 g of H3BO3.
B. 30.33 g of H2.
Explanation:
We'll begin by writing a balanced equation for the reaction. This is given below:
B2H6 + 6H2O → 2H3BO3 + 6H2
Next, we shall determine the mass of B2H6 that reacted and the masses of H3BO3 and H2 produced from the balanced equation equation. This can be obtained as follow:
Molar mass of B2H6 = (2×11) + (1×6) = 22 + 6 = 28 g/mol
Mass of B2H6 from the balanced equation = 1 × 28 = 28 g
Molar mass of H3BO3 = (1×3) + 11 + (3×16) = 3 + 11 + 48 = 62 g/mol
Mass of H3BO3 from the balanced equation = 2 × 62 = 124 g
Molar mass of H2 = 2×1 = 2 g/mol
Mass of H2 from the balanced equation = 6 × 2 = 12 g
From the balanced equation above:
28 g of B2H6 reacted to produce 124 g of H3BO3 and 12 g of H2.
A. Determination of the mass of H3BO3 produced from the reaction.
This can be obtained as follow:
From the balanced equation above,
28 g of B2H6 reacted to produce 124 g of H3BO3.
Therefore, 70.76 g of B2H6 will react to produce = (70.76 × 124)/28 = 313.37 g of H3BO3.
Therefore, 313.37 g of H3BO3 were obtained from the reaction.
B. Determination of the mass of H2 produced from the reaction.
This can be obtained as follow:
From the balanced equation above,
28 g of B2H6 reacted to produce 12 g of H2.
Therefore, 70.76 g of B2H6 will react to produce = ((70.76 × 12)/28 = 30.33 g of H2.
Therefore, 30.33 g of H2 were obtained from the reaction.
Which of the following is considered an ionic solid? a) (NH4)2CO3 b) CBr4 c) SeBr2 d) XeF4 e) None of the above is an ionic solid.
Answer: NH4)2CO3
Explanation:
Ionic solids are the solids that are simply held together by ionic bonds. Ionic bonds are lattices that are typically made up of oppositely charged ions and they usually possess a high melting point.
An example of ionic bond is NH₄)₂CO₃ which is referred to as Ammonium carbonate. This is a salt and it readily degrades upon heating to carbon dioxide and gaseous ammonia.
can some one help The function of the cell wall in a plant cell is Question 2 options: Allowing material to pass in and out of the cell Uses carbon dioxide, water and energy from the sun to make sugar Breaks sugar down into ATP which the cell can use for energy Provides support and protection for the cell
Answer:
the protection one
Explanation:
the cell wall acts a barrier
1- Science that deals with the identification and quantification of the components of material systems
A)Analytical Science
B)Biochemistry
C)Organic Chemistry
D) Inorganic Chemistry
Q1-(30 Marks) Choose the correct answer
Answer:
Analytical science
Explanation:
chemical test of acetylene in the laboratory
If ΔH vaporization of water (H2O) is 40.7 kJ/mol,
and the ΔS for vaporization of H2O is 109 J/mol K,
what is ΔG for water vaporization at 350K?
Include units.
Answer:
2.6 kJ/mol
Explanation:
Step 1: Given data
Standard enthalpy of vaporization of water (ΔH°): 40.7 kJ/molStandard entropy of vaporization of water (ΔS°): 109 J/mol.KAbsolute temperature (T): 350 KStandard Gibbs free energy of vaporization of water (ΔG°): ?Step 2: Calculate ΔG°
We can calculate ΔG° using the following expression.
ΔG° = ΔH° - T × ΔS°
ΔG° = 40.7 kJ/mol - 350 K × 0.109 kJ/mol.K
ΔG° = 2.6 kJ/mol
The change in Gibbs free energy, ΔG for the water is 2.55 KJ/mol
Data obtained from the questionFrom the question given above, the following data were obtained:
Standard enthalpy of vaporization of water (ΔH°) = 40.7 kJ/molStandard entropy of vaporization of water (ΔS°) = 109 J/Kmol = 109 / 1000 = 0.109 KJ/Kmol Absolute temperature (T) = 350 KStandard Gibbs free energy (ΔG°) =? How to determine the Gibbs free energy, ΔG°The Gibbs free energy, ΔG° can be obtained as illustrated below:
ΔG° = ΔH° – TΔS°
ΔG° = 40.7 – (350 × 0.109)
ΔG° = 40.7 – 38.15
ΔG° = 2.55 KJ/mol
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E
1
1 point
Which of the following is an elemental substance?
Select all the correct answers.
Mercury
2
Oxygen (O2)
3
Platinum
Chlorine (C12)
Carbon Dioxide (CO2)
Answer:
oxygen and Carbon dioxide
In which of does the convection only occur in
A. Gases
B. Fluids
C. Liquids
D. Solids
Answer:
B. Fluids
I hope this helps!
Answer:
B
Explanation:
A pure copper penny contains approximately 2.9×1022 copper atoms. Use the following definitions to determine how many ______ of copper atoms are in a penny. 1doz=12 1gross=144 1ream=500 1mol=6.022×1023 Part A dozens Express your answer in dozens to two significant figures.
Complete question is;
A pure copper penny contains approximately 2.9 × 10^(22) copper atoms.
1 doz = 12
1 gross = 144
1 ream = 500
1 mol = 6.022 × 10^(23)
Use these definitions to determine the following:
A) How many dozens of copper atoms are in a penny.
B) How many gross of copper atoms are in a penny
C) How many reams of copper atoms are in a penny.
D) how many moles of copper atoms are in a penny?
All answers can be rounded to two significant figures
Answer:
A) 2.4 × 10^(21) dozens
B) 2.01 × 10^(20) gross
C) 5.8 × 10^(19) reams
D) 0.048 mol
Explanation:
A) A dozen contains 12.
Therefore, 2.9 × 10^(22) copper atoms will contain;
(2.9 × 10^(22))/12 dozens = 2.42 × 10^(21).
In 2 significant figures, we have;
2.4 × 10^(21) dozens
B) 1 gross = 144
Therefore, 2.9 × 10^(22) copper atoms will contain;
(2.9 × 10^(22))/144 gross ≈ 2.01 × 10^(20) gross
C) 1 ream = 500
Therefore, 2.9 × 10^(22) copper atoms will contain;
(2.9 × 10^(22))/500 reams = 5.8 × 10^(19) reams
D) 1 mol = 6.022 × 10^(23)
Therefore, 2.9 × 10^(22) copper atoms will contain;
(2.9 × 10^(22))/(6.022 × 10^(23)) = 0.048 mol
What is the volume of a sample of matter with a density of 6 and a mass of 6 cm3?
Answer:
We have the final answer as
1.0 cm³Explanation:
The volume of a substance when given the density and mass can be found by using the formula
[tex]volume = \frac{mass}{density} \\[/tex]
From the question
mass = 6 g
density = 6 g/cm³
It's volume is
[tex]volume = \frac{6}{6} = 1 \\ [/tex]
We have the final answer as
1.0 cm³Hope this helps you
3 points
What is the energy (Joules) of violet light with a frequency = 3.43 x 10^14
1/s? *
4.54x10^-19 J
1.99x10^-25 J
1.93 x 10^-48 J
O 2.27 x 10^-19 J
Pls help me
Answer:
4.54x10^-19 J
1.99x10^-25 J
1.93 x 10^-48 J
Part Of flowers that contains pollen is
Please answer right
Answer:
its the stamen, it also supports the Anther.
Answer:
The Stamen
Explanation:
The stamen is a slender filament supporting the anther, it is what produces and holds pollen in flowers.
You bought a new car and estimated that your monthly payment would be $312. However, your actual payment amount is $325. How much error was in your estimate?
PLEASE HELP ME, I HAVE NO IDEA HOW TO DO THIS :(
Lol . same here. If u get any ideas please let me know
Answer:
See the picture you have to write like this
How many grams are there in 1.00x10 24 molecules of BCI3
Answer:
194.569 g
Explanation:
6.022×10^23 molecules = 117.17 g
1 molecules = 117.17/ 6.022×10^23
So, 1×10^24 molecules = (117.17×1×10^24)/(6.022×10^23)= 194.569 g
how many atoms are in 2 miles of h2o
Answer:
one mole of water contains 6.02 x 1023 MOLECULES of water.
But each molecule of water contains 2 H and 1 O atom = 3 atoms, so there are approximately 1.8 x 1024 atoms in a mole of water.
Explanation:
hope it helps you paigegeorge
When measuring solid NaOH in pellet form, explain why you won’t be able to measure exactly 1.000 grams. What are the consequences of this?
Answer:
Explanation:
Pellet form of NaOH is highly hygroscopic . It absorbs moisture from air and its weight is increased by the time one tries to weigh one gram of it . Moreover it also reacts with carbon dioxide gas of atmosphere to form sodium carbonate .
2 NaOH + CO₂ = Na₂CO₃ + H₂0.
It also increases its weight .
Which of the following is a buffer system?
A. NaCl and NaNO3
B. H2CO3 and KHCO3
C. HCl and NaOH
D. H2O and HCl
E. NaCl and NaOH
Answer:
B. H2CO3 and KHCO3
Explanation:
The buffer system is a system in which the solution deny for change in the ph level i.e. at the time when the acid is added to it. It can be made either in a weak acid and salt or can be a weak base and its salt. Now when the acid is added to a buffer so the ratio is not impacted due to which it does not change sufficient for pH level
As per the given options, the third one is correct as the H2CO3 denotes a weak acid and the KHCO3 represents the salt. And these two solution does not create any change in the level of pH
Therefore the option B is correct
What is the mass, in grams, of the ethyl alcohol that exactly fills a 220 mL container? The density of ethyl alcohol is 0.789 g/mL. Group of answer choices 170 g 173.58 g 280 g 278.833967 g
Answer:
[tex]m=173.58g[/tex]
Explanation:
Hello,
In this case, since the density is the ratio of the mass and volume:
[tex]\rho =\frac{m}{V}[/tex]
For the given density and volume, the correct mass which fills the given volume is:
[tex]m=\rho *V=0.789g/mL*220mL\\\\m=173.58g[/tex]
Best regards.
Oxalic acid, H2C2O4*2H2O (molar mass = 126.07 g/mol) is oftenused as a primary standard for the standardization of a NaOHsolution. If 0.147 g of oxalic acid dihydrate is nutralizedby 23.64mL of a NaOH solution, what is the molar concentration ofthe NAOH solution? Oxalic acid is a diprotic acid. (What is thebalanced equation?)
Answer:
0.09865M of NaOH
Explanation:
As a diprotic acid, 1 mole of oxalic acid reacts with 2 moles of NaOH as follows:
H2C2O4 + 2 NaOH → 2 H2O + Na2C2O4
With the mass of the acid and its molar mass we can obtain the moles of oxalic acid. Twice these moles are the moles of NaOH in the solution. As you required 23.64mL = 0.02364L of the NaOH, you can knkow molarity, thus:
Moles Oxalic acid:
0.147g * (1mol / 126.07g) = 1.166x10⁻³ moles Oxalic acid.
Moles NaOH:
1.166x10⁻³ moles Oxalic acid * (2 moles NaOH / 1 mole H2C2O4) = 2.332x10⁻³ moles NaOH
Molarity:
2.332x10⁻³ moles NaOH / 0.02364L =
0.09865M of NaOHDecaying plants and animals are important to an ecosystem because they
A.
cause disease in living organisms.
B.
reduce soil erosion.
C.
recycle oxygen to the air.
D.
return nutrients to the soil.
Answer:
The option D is correct answer.
Decaying pants and animals are important to the ecosystem as they return the nutrients to the soil.
What is an ecosystem?Ecosystem is defined as a system which consists of all living organisms and the physical components with which the living beings interact. The abiotic and biotic components are linked to each other through nutrient cycles and flow of energy.
Energy enters the system through the process of photosynthesis .Animals play an important role in transfer of energy as they feed on each other.As a result of this transfer of matter and energy takes place through the system .Living organisms also influence the quantity of biomass present.By decomposition of dead plants and animals by microbes nutrients are released back in to the soil.
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