Answers
Related Questions
Radioactive decay follows first-order kinetics. If a sample of I-131 decays from 25.0 mg to 8.25 mg in 12.8 days, what is the rate constant, k?
Answers
Answer:
k = 0.0866 days⁻¹
Explanation:
The isotope decay of the atom follows the equation:
ln [A] = -kt + Ln[A]₀
Where [A] is the amount of the isotope after time t = 8.25mg
Time = 12.8days
k is rate constant
[A]₀ is actual amount of the isotope = 25.0mg
Replacing:
ln 8.25mg = -k*12.8days + ln 25.0mg
2.11 - 3.22 = -k*12.8days
-1.11 = -k12.8days
k = 0.0866 days⁻¹
Equation for questions 1-4:
4A1+302 → 2A1203
How many moles of oxygen are needed to react with 7.5 moles of aluminum
Answers
Answer:
5.625 moles of oxygen, O₂.
Explanation:
The balanced equation for the reaction is given below:
4Al + 3O₂ —> 2Al₂O₃
From the balanced equation above,
4 moles of Al reacted with 3 moles of O₂.
Finally, we shall determine the number of mole of O₂ required to react with 7.5 moles of aluminum, Al. This can be obtained as illustrated below:
From the balanced equation above,
4 moles of Al reacted with 3 moles of O₂.
Therefore, 7.5 moles of Al will react with = (7.5 × 3)/4 = 5.625 moles of O₂.
Thus, 5.625 moles of O₂ is needed for the reaction.
why a “control” is important in a case-control study of a disease?
Answers
Answer:
Explanation:
Purpose of Case Control Studies
To determine whether or not an association exists between a disease and a particular risk factor. To start with a group of people with disease and work back to see whether a possible risk factor may be the cause. It may be the first step in testing a hypothesis.
Plz help :’(
Using structural formula, write a balanced equation for the following and name the organic product.
2-methylbutan-1-ol + hot conc H2SO4
Answers
Explanation:
2-metylbutene should be the profuct
Specify the number of possible isomers of bromodimethylbenzene. 6 Write the name of one of these isomers. Abbreviate ortho (o), meta (m) and para (p), no italics, if you elect to use these terms.fill in the blank 2 Specify the number of possible isomers of aromatic compounds with the formula C7H8O. ___ Write the name of one of these isomers. Abbreviate ortho (o), meta (m) and para (p), no italics, if you elect to use these terms. fill in the blank 4
Answers
Answer:
Explanation:
See attached file .
The number of possible isomers of Bromodimethylbenze are 6. One of the isomers is 2 Bromo - m -xylene. The number of possible isomers of an aromatic compound [tex]\rm C_7H_8O[/tex] are 5. One of these isomers has been o - cresol.
(a). Bromodimethylbenze has also been known as bromoxylene. The compound has been consisted of 1 benzene ring with 2 methyl groups and a bromine atom.
The possible isomers of bromoxylene are:
4 Bromo - o -xylene3 Bromo - o -xylene2 Bromo - m -xylene4 Bromo - m -xylene5 Bromo - m -xylene2 Bromo - p -xylene(b). Aromatic compound with formula [tex]\rm C_7H_8O[/tex] has been the benzene compound. The compound has been consisted of a benzene ring with 1 methyl group and oxygen atom.
The possible isomers of [tex]\rm C_7H_8O[/tex] are:
Benzyl alcoholAnisolo - cresolp - cresolm - cresolThus, the number of possible isomers of Bromodimethylbenze are 6. One of the isomers is 2 Bromo - m -xylene. The number of possible isomers of an aromatic compound [tex]\rm C_7H_8O[/tex] are 5. One of these isomers has been o - cresol.
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g 8. A hydrogen atom is initially a rest and in the ground state. A proton with kinetic energy 1000 eV scatters off the atom. In the process the hydrogen atom is ionized. The kinetic energy of the ionized electron is measured to be 15.2 eV and the kinetic energy of the proton produced from the ionization of hydrogen is 4.3 eV. What would be the final kinetic energy of the projectile proton after the collision
Answers
Answer:
Explanation:
Ionization energy of hydrogen atom is 13.6 eV . This energy will be provided by energetic proton , the kinetic energy of which is 1000 eV. The kinetic energy of ionized electron is 15.2 eV . Kinetic energy of proton produced from from the ionization of hydrogen or the nucleus of the hydrogen atom is 4.3 eV . All these energy must have come from kinetic energy of initial proton.
So kinetic energy of projectile proton after collision
= 1000 - ( 13.6 + 15.2 + 4.3 ) eV.
= 966.9 eV .
14
Use the data in the table to work out the state of each substance at 25 °C. *
(3 Points)
Substance
Melting point (°C)
Boiling point (°C)
State at 25 °C
methane
-182
-164
dodecane
-10
216
phenol
43
182
(3 marks)
Enter your answer
This question is required.
16
Answers
Answer:
Explanation:
The melting point of a substance is the temperature at which its melt. The state of a substance is dependent on it's melting temperature. Generally, melting point above 25 °C is a solid.
This means phenol is a solid
Duodecane has melting point below 25 °C hence it is either a liquid or gas. However its boiling point of 216 °C means it would require higher temperature to boil it. Since 25 °C is less than 216 °C it means that it would remain in the liquid state.
Methane has melting point below 25 °C hence it is either a liquid or gas. However its boiling point of -164 °C means it boils easily even at very low temperatures. Since 25 °C is greater than -164 °C it means that it would exist in the gaseous state
1. What is the purpose of the lab?
2. What is your hypothesis for this experiment?
3. What methods are you using to test this hypothesis?
Outline the steps of the procedure in full sentences.
Section II: Data and Analysis
4. What graphs would clearly represent the trends in your data?
Your Student Guide includes information on which graphs to construct. Each graph should have the following items:
a. An appropriate title
b. Appropriate labels for each axis
c. An appropriate scale for each axis
d. The correct units for the data
Complete a rough sketch of each graph.
5. What do the data in your graphs tell you?
Explain in one or two sentences what trend is shown in each of your graphs.
Section III: Conclusions
6. What do the data tell you about your hypothesis?
State how your hypothesis is either supported OR refuted by the data.
7. How do the data support your claim above?
Explain your statement above. Be sure to refer to specific pieces of data from your experiment that support your argument.
8. If you could repeat the experiment and make it better, what would you do differently and why?
There are always ways that experiments can be improved. Now that you are a veteran of this experiment and have experience with the procedure, offer some advice to the next scientist about what you suggest and why.
Answers
Answer:
1)To familiarize students with experimental apparatus, the scientific method, and methods of data analysis so that they will have some idea of the inductive process by which the ideas were originated. To teach how to make careful experimental observations and how to think about and draw conclusions from such data.
2)The hypothesis is an educated guess as to what will happen during your experiment. The hypothesis is often written using the words "IF" and "THEN." For example, "If I do not study, then I will fail the test." The "if' and "then" statements reflect your independent and dependent variables.
3)Specify the Null Hypothesis.
Specify the Alternative Hypothesis.
Set the Significance Level.
Calculate the Test Statistic and Corresponding P-Value.
Drawing a Conclusion.
4)Line charts, or line graphs, are powerful visual tools that illustrate trends in data over a period of time or a particular correlation. For example, one axis of the graph might represent a variable value, while the other axis often displays a timeline.
5)
Answer:
To familiarize students with experimental apparatus, the scientific method, and methods of data analysis so that they will have some idea of the inductive process by which the ideas were originated. To teach how to make careful experimental observations and how to think about and draw conclusions from such data.
2)The hypothesis is an educated guess as to what will happen during your experiment. The hypothesis is often written using the words "IF" and "THEN." For example, "If I do not study, then I will fail the test." The "if' and "then" statements reflect your independent and dependent variables.
3)Specify the Null Hypothesis.
Specify the Alternative Hypothesis.
Set the Significance Level.
Calculate the Test Statistic and Corresponding P-Value.
Drawing a Conclusion.
4)Line charts, or line graphs, are powerful visual tools that illustrate trends in data over a period of time or a particular correlation. For example, one axis of the graph might represent a variable value, while the other axis often displays a timeline.
Explanation:
To familiarize students with experimental apparatus, the scientific method, and methods of data analysis so that they will have some idea of the inductive process by which the ideas were originated. To teach how to make careful experimental observations and how to think about and draw conclusions from such data.
2)The hypothesis is an educated guess as to what will happen during your experiment. The hypothesis is often written using the words "IF" and "THEN." For example, "If I do not study, then I will fail the test." The "if' and "then" statements reflect your independent and dependent variables.
3)Specify the Null Hypothesis.
Specify the Alternative Hypothesis.
Set the Significance Level.
Calculate the Test Statistic and Corresponding P-Value.
Drawing a Conclusion.
4)Line charts, or line graphs, are powerful visual tools that illustrate trends in data over a period of time or a particular correlation. For example, one axis of the graph might represent a variable value, while the other axis often displays a timeline.
Elements are solid liquid and gas substance that can be found on earth which statements best describes an element
Answers
Answer:
i guess
Explanation:
we will never know
Question 4 (2 points)
What is the percent composition of oxygen in aluminum phosphate? Round answer
to 3 significant figures.
A/
Answers
Answer:
52.5%.
Explanation:
The formula for aluminum phosphate is => AlPO₄
Next, we shall determine the molar mass of aluminum phosphate, AlPO₄. This can be obtained as follow:
Molar mass of AlPO₄ = 27 + 31 + (16×4)
= 27 + 31 + 64
= 122 g/mol
Next, we shall determine the mass of oxygen (O) in AlPO₄. This can be obtained as follow:
There are 4 atoms of O in AlPO₄.
Mass of O = 4 × 16 = 64 g
Finally, we shall determine the percent composition of oxygen in aluminum phosphate, AlPO₄. This can be obtained as follow:
Mass of O = 64 g
Molar mass of AlPO₄ = 122 g/mol
Percentage composition of oxygen =?
Percentage composition = mass of element/Molar mass of compound ×100
Percentage composition = 64/122 × 100
Percentage composition = 52.5%
Therefore, the percent composition of oxygen in aluminum phosphate, AlPO₄ is 52.5%
Can someone help me out with the question
Answers
5cookies 30pickles
what is the difference between evaporation and boiling
Answers
Evaporation is slower, occurs only from the surface of the liquid, does not produce bubbles, and leads to cooling. Boiling is faster, can occur throughout the liquid, produces lots of bubbles, and does not result in cooling.
Answer/Explanation:
Let's define both terms
Boiling: is defined as a process whereby the liquid state is turned into gaseous state at a specific boiling point. And it is a fast process.
Evaporation: is defined as a process whereby a natural process in which the increase in temperature or pressure causes liquid to change into gas.
Difference between boiling and evaporation
In boiling, temperature of the liquid remains constant. While in evaporation, temperature of the liquid reduces
In boiling, temperature is required only at boiling point while in evaporation, temperature occurs at any given temperature.
In boiling, bubbles are formed while in evaporation, bubbles are not formed.
In boiling, a source of energy is required while in evaporation, the surrounding supplies the energy required.
Boiling produces heat and does not lead to liquid cooling, evaporation leads to liquid cooling.
The molecules of the liquid move faster in boiling than in evaporation
plzzzz help due in like 10 min!!!
Answers
Answer: for question 4, the answer would most likely be movement of air, water and rock
Explanation:
Answer:
Explanation:
It is really blurry i cant really see the pic
a. How many moles of hydrogen would be needed to produce 12 moles of ammonia
Answers
8 moles and I hope that this helps
And D. It’s long stems Sorry couldn’t fit D in the picture
Answers
Answer:
I think the correct answer is a
Explanation:
that's the only part that could really be used to protect itself,
How many liters of P, are in 3.5x1022 molecules at STP?
Answers
Answer: they giving you some hard question
Explanation:
i dont know know what the answer is do you have any answer options
What is the compound name for magnesium sulfur
Answers
Answer:
MgS is the formula and Magnesium sulfide is compound name
Explanation:
Answer:
MgS
Explanation:
someone please help!! I need an answer by 10:20
“I used to think _____________ about electricity, and now I think….”
Im in 7th grade btw
100 points!!!
Answers
Answer:
"I used to think a lot about electricity, and now I think..."
or a synonym of it.
Explanation:
Beth wrote the following description of the life cycle of non-flowering, seed-bearing plants. Read her description and find the mistake.
"Non-flowering, seed-bearing plants go through four major stages in their life cycles. The first stage is when the plant is a seed from a cone. The second stage is when the plant sprouts out of the seed and the cones begin to grow. The third stage is the when the plant is a seedling. The fourth stage is when the plant is a bigger seedling."
What statement corrects the error in Beth's report? (10 points)
a
There are five stages in the life cycle of non-flowering, seed-bearing plants, not four.
b
Cones do not begin to grow in the second stage.
c
The third stage is when the plant sprouts out of the seed and the flower grows.
d
The fourth stage is when the plant is an adult plant growing leaves and cones which produce more seeds.
Answers
Answer:
Ok so I know the answer is not B, cones do not grow on the second stage.
Explanation:
I took the test my self and I choose that one and it was wrong. Sorry if this doesn't help I will put the correct answer one here someday
Answer:
the answer is b
Explanation:
because its the only true onE and i hope i dont fail soooooo
In this case you have unlimited iron, but only 6.40 moles of oxygen (O2). How much Fe2O3 can you produce?
Answers
Answer: 682 grams
Explanation:
The balanced chemical reaction is:
[tex]4Fe+3O_2\rightarrow 2Fe_2O_3[/tex]
[tex]O_2[/tex] is the limiting reagent as it limits the formation of product and [tex]Fe[/tex] is the excess reagent.
According to stoichiometry :
3 moles of [tex]O_2[/tex] produce = 2 moles of [tex]Fe_2O_3[/tex]
Thus 6.40 moles of [tex]O_2[/tex] will produce=[tex]\frac{2}{3}\times 6.40=4.27moles[/tex] of [tex]Fe_2O_3[/tex]
Mass of [tex]Fe_2O_3=moles\times {\text {Molar mass}}=4.27moles\times 159.69g/mol=682g[/tex]
Thus 682 g of [tex]Fe_2O_3[/tex] will be produced from 6.40 moles of oxygen
What is the difference between a renewable and non-renewable source of energy? Give 3 examples of each.
Answers
Answer:
There are two major categories of energy: renewable and non-renewable.
Non-renewable energy resources are available in limited supplies, usually because they take a long time to replenish. The advantage of these non-renewable resources is that power plants that use them are able to produce more power on demand. The non-renewable energy resources are:
CoalNuclearOilNatural gasRenewable resources, on the other hand, replenish themselves. The five major renewable energy resources are:
SolarWindWater, also called hydroBiomass, or organic material from plants and animalsGeothermal, which is naturally occurring heat from the earthWhile renewable energy resources have the advantage of unlimited supply over the long haul, they are limited in their availability at any given moment.
For example, the sun rises each day, but its ability to generate power is limited when its cloudy. Another disadvantage is that power plant operators can’t crank up renewable energy production when people are consuming more power, such as on a hot day when many people are running air conditioners at the same time.
Answer this correctly please...
1. Two body systems Which of the following is NOT a part of the integumentary system of the body?
A. hair
B. bones
C. skin
D. finger and toe nailswork together to help remove waste products from blood.
2. What are these two systems?
A. circulatory and excretory
B. skeletal and digestive
C. circulatory and integumentary
D. muscular and excretory
3. One of the functions of the endocrine system in the body is to -
A. circulate blood to all parts of the body
B. collect waste products and remove them from the body
C. provide a strong framework for the body
D. produce enzymes to help digest food
6. When a person’s body needs food, the brain helps maintain homeostasis by sending signals that make the person
A.feel hungry.
B. perspire.
C. put on a sweater.
D. feel tired
7. The largest human body organ which regulates temperature and serves as a barrier against harmful microorganisms belongs to the -
A. circulatory system
B. nervous system
C. digestive system
D. integumentary system
8. Which of the following is NOT a part of the respiratory system?
A. diaphragm
B. esophagus
C. lungs
D. trachea
9. What would happen to your body if you had little or no bone marrow?
A. Your other systems would make up for it
B. You would not have enough red blood cells
C. Nothing would happen to you.
D. You would not have enough cartilage.
Answers
Answer:
1. B
2. C
3. B or D
6. A
7. D
8. A
9. A
Explanation:
Brainliest plz answered to the best of my abilitys
How many protons does isotope of carbon- 14 atom have
Answers
Answer:
Number of protons in Carbon - 14 atom [tex]6[/tex]
Explanation:
The atomic number of carbon 14 atom is [tex]14[/tex]
Number of neutrons in the nucleus of Carbon-14 atom [tex]= 8[/tex]
Atomic number is equal to the sum of neutrons and protons
Number of protons in Carbon - 14 atom [tex]= 14 -8 = 6[/tex]
1 point
5. A drug or other chemical compound whose manufacture, distribution,
possession, and use is regulated by the legal system is referred to as a
poison.
a.poison
b. narcotic
c. toxin
d. controlled substance
Answers
I'm pretty sure its D because if it's manufactured and distributed its likely not toxin or poison. a narcotic could be a controlled substance so that's why I'm leaning towards D
Hypothesis: What do you think will happen when you add more magnets to the set up?
Answers
Answer:
........................
How and why do we see colors?
Answers
Answer:
Light receptors within the eye transmit messages to the brain, which produces the familiar sensations of color. Newton observed that color is not inherent in objects. Rather, the surface of an object reflects some colors and absorbs all the others. We perceive only the reflected colors.
How are the atmospheres on Jupiter and Saturn different than those on Uranus and Neptune?
Answers
Answer:
The atmospheres of Jupiter and Saturn are made almost entirely of hydrogen and helium, although there is some evidence they contain hydrogen compounds. The there is Uranus and Neptune that are made primarily of hydrogen compounds, with smaller traces of hydrogen, helium, metal and rock.
Explanation:
Hope this helps.
WILL AWARD BRAINLIEST!!! A chemist performs a reaction combining 100.1 g of aluminum chloride (AlCl3), and 57.2 g of sodium hydroxide (NaOH). The products are aluminum hydroxide (Al(OH)3) and sodium chloride (NaCl).
a. Please write out the balanced equation for this reaction.
b. Assuming all the aluminum chloride is consumed in this reaction, how many grams of aluminum hydroxide will form? Work must be shown to earn credit.
c. If all the sodium hydroxide is used up, how many grams of aluminum hydroxide can be formed? Work must be shown to earn credit.
d. What is the theoretical yield of this reaction? Which reagent is limiting? Explain your answer.
Answers
a.The balanced reaction between [tex]AlCl_3[/tex] and NaOH is:
[tex]AlCl_3 + 3NaOH[/tex] → [tex]Al(OH)_3 + 3NaCl[/tex] is the balanced reaction.
b.58.55g of aluminum hydroxide will form? Work must be shown to earn credit
c. 6.50 g grams of aluminum hydroxide can be formed.
d.[tex]Al(OH)_3[/tex] produced from NaOH is less, NaOH will be the limiting reagent. The amount of [tex]Al(OH)_3[/tex] actually produced is 4.13 g.
What is a balanced chemical equation?An equation that has an equal number of atoms of each element on both sides of the equation is called a balanced chemical equation.
a.The balanced reaction between [tex]AlCl_3[/tex] and NaOH is:
[tex]AlCl_3 + 3NaOH[/tex] → [tex]Al(OH)_3 + 3NaCl[/tex] is the balanced reaction.
b) Given mass of [tex]AlCl_3[/tex] = 100.1 g
Molar mass of [tex]AlCl_3[/tex] = 133.34 g/mol
moles of [tex]AlCl_3[/tex] = 100.1 g ÷133.34 = 0.7507 moles
Based on the reaction stoichiometry:
1 mole of [tex]AlCl_3[/tex] produces 1 mole of [tex]Al(OH)_3[/tex]
# moles of [tex]Al(OH)_3[/tex] = 0.7507 moles
Molar mass [tex]Al(OH)_3[/tex] = 78 g/mol
Amount of [tex]Al(OH)_3[/tex] produced = 0.7507 moles x 78 = 58.55g
c) Given mass of NaOH = 57.2 g
Molar mass of NaOH= 40 g/mol
moles of NaOH = 57.2 g ÷ 40 = 1.43 moles
Based on the reaction stoichiometry:
3 moles of NaOH produces 1 mole of [tex]Al(OH)_3[/tex]
moles of [tex]Al(OH)_3[/tex] produced = 1.43÷ 3 = 0.4766 moles
Molar mass [tex]Al(OH)_3[/tex] = 78 g/mol
Amount of [tex]Al(OH)_3[/tex] produced = 0.4766 78 = 6.50 g
d) Since moles of [tex]Al(OH)_3[/tex] produced from NaOH is less, NaOH will be the limiting reagent. The amount of [tex]Al(OH)_3[/tex] actually produced is 6.50 g.
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How does a liquid change as it moved from one container to another?
Answers
Answer:
gas
Explanation:
Plz help with this last question ----- What information does an acid or base equilibrium constant give.
Answers
The information of concentration of product and reactant at equilibrium is given by acid or base equilibrium constant give.
What is equilibrium constant?Equilibrium constant tells about the relative ratio of the concentration of product and reactant at the equilibrium.
As the name acid or base equilibrium constant suggested that they also give the relation between the concentration of the reactants and products at equilibrium.
HA + H₂O ⇄ A⁻ + H₃O⁺
Acid equilibrium constant is denoted as Ka and for the above reaction at equilibrium it can be written as:
Ka = [H⁺] [A⁻] / [HA]
Similarly, base equilibrium constant Kb is also define as the ratio of the concentration of product to the concentration of reactant.
Hence, an acid or base equilibrium constant give information about concentration.
To know more about acid or base equilibrium constant, visit the below link:
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