Answer:
They did not repeat their tests multiple times.
Explanation:
It may seem that the question is incomplete. The complete question is as below: Dominic and Eva are using the same type of stopwatches to measure the time it takes for a chemical reaction to occur. They each use the same stopwatch to measure the time. These are their results:
Dominic: 78 seconds
Eva: 81 seconds
Why are their results unreliable and can lead to a pseudoscientific claim?
They did not repeat their tests multiple times.
They used the same type of stopwatch.
They did not change the reactants in their chemical reactions.
Only one person should have collected the data.
Dominic and Eva's results are unreliable and can lead to a pseudoscientific claim because they did not repeat their tests multiple times.
Repeating the test multiple times and finding the average of the measurement will minimize the chance of having error in the measurement and improve the accuracy of the outcome.
Thus, without repeated measurement, the reliability and the validity of the measurement would be in doubt.
Mendeleev's arrangement of elements in the periodic table was based on the observations and experiments of his predecessors who studied the mass and properties of elements. (2 points) True False
Answer: True
Explanation:
Mendeleevs periodic classification is based on the atomic masses of the elements.
Do heavy metals like lead and arsenic cause damage to human DNA
Answer:
Yes
Explanation:
Some environmental factors- chemical, physical (UV), and biological (poisonous plants)- have the capability to damage DNA. This can lead to mutation, cell death, and several ailments.
Chemicals such as pesticides and heavy metals can be found in the environment (air, water) or in some consumer products.
The presence of Lead and a reactive oxygen species can result in DNA damage. Arsenic is classified as a carcinogen (cancer-causing substance).
More details are found in scientific articles online, but here's a helpful snippet- "heavy metal exposure can contribute to genetic damage by inducing double strand breaks (DSBs) as well as inhibiting critical proteins from different DNA repair pathways"
Lead and arsenic are heavy metals that are considered carcinogens. These metals cause alteration and damage to the genetic material and protein synthesis.
What are carcinogens?Carcinogens are said to be a substance that can lead to cancer in an organism and are produced naturally from viruses and ultraviolet rays or mna made by cigarette smoking and chemicals.
Their high exposure causes the breaking of the double strand of the DNA molecule in the cells that inhibits and prevents protein formation leading to interference with the DNA repair pathways.
Cadmium, lead, arsenic, etc., are heavy metals that are released by human activities and alter the genetic mechanism and composition leading to mutation and disorders like skin cancers, lung cancer, etc.
Therefore, lead and arsenic is carcinogens that damage DNA.
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Which reaction is exothermic? CH4 + 2O2 Right arrow. CO2 + 2H2O + 891 kJ NH4NO3 + H2O + 25 kJ Right arrow. NH4+(aq) + NO3-(aq) 2H2O + 286 kJ Right arrow. 2H2 + O2 N2 + O2 + 181 kJ Right arrow. 2NO
Answer:
ch4 + 2o2 gives co2+2h2o +891kj
Explanation:
becoz 891kj heat energy is given out
exothermic process means heat energy is given out/ released
Among the given reactions the exothermic reaction is option a. The reaction between methane and oxygen giving out carbon dioxide and water with 891 KJ of heat energy.
What is exothermic reaction?An exothermic reaction is the reaction in which heat is evolved from the reaction system to the surroundings. The reaction container will be too hot to touch.
The enthalpy change for an exothermic reaction is negative. Whereas that for an endothermic reaction is positive where, heat is absorbed into the reaction system.
For the given reactions, all other reactions except option a are intaking some heat energy that's why written in the left side of arrow which are endothermic. Option a is the combustion of methane gas and it is exothermic.
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Question 7 (5 points)
(01.03 LC)
The atoms and molecules in a liquid are in constant motion. As temperature decreases, what is true of the particles in the liquid? (5 points)
a.) The distance between the particles increases.
b.) The attraction between the particles decreases.
c.) The rate of particle movement decreases.
d.) The potential energy of the particles decreases.
Answ Es la B .
Explanation
By raising the temperature of a liquid, it turns into a gas, therefore its particles will have more movement and its kinetic energy will increase. the more you raise the temperature, the more space they will have between the molecules.
A scientist wrote a report that communicates the steps he performed in an investigation, the data he gathered, and his conclusions. A second scientist used the report to carry out the same investigation. However, her results were very different. Are the results of the investigation described below valid? If not, what should the scientists do next? Explain your reasoning.
Answer:
yes, this is an acceptable practice in research.
Explanation:
Note that, having a different result in one's research does not imply it is automatically invalid. However, because there may have been some errors or limitations in the previous work by the male researcher, it is possible that the later results are more accurate, even though she used the same procedures. She may have been more careful when calculating her results.
Answer:
Since the results did not match, she should repeat the investigation again. If the data still cannot be replicated, then the results are not valid. In that case, the next step is to restart the process of inquiry from the beginning. An improved design might produce valid, repeatable results.
Explanation:
If anyone is good at chemistry do you mind helping? (●'◡'●)
• Before the balloon was placed inside the hot water, the pressure was the same inside and outside the balloon. The hot water raised the kinetic energy of the air molecules inside the balloon, expanding the balloon, through thermal expansion.
• (1) the pressure of air inside the balloon increased, (2) the volume of the inside of the balloon increased as well, and (3) the temperature of the balloon increased. Note that pressure and volume are inversely proportional, and pressure and temperature are directly proportional. Therefore as the temperature increases, the pressure inside will increase, causing an increase in the volume. At a certain point though the volume will increase too much as to cause a significant decrease in pressure.
• The air molecules will gain kinetic energy, hence (1) increasing the molecules's speed, and (2) heating the air molecules.
Which bond is intermediate in terms of strength? why is it weaker than the strongest? ap bio?
Answer:
Ionic bond is the intermediate in strength.
Explanation:
Ionic bond is weaker than covalent bond and stronger than hydrogen bond in strength because in ionic bond, the atoms attract each other due to opposite in charge. Ionic bond is a type of bond in which one atom losses electron completely and become cation (positive charge) while the other atom receive the electron and become anion (negative charge). so they attract each other due to opposite charges.
Question 5
Above is the grades for 17 students in Chemistry class. What percent received a B+? Make sure you round your answer
to two decimal places.
Answer:
There are 17.64% students received B+ grades.
Explanation:
It is given that,
Total number of students in chemistry class is 17
We need to find the percentage received by B+.
Number of students having B+ grades are 3 (from graph)
Required percentage = [tex]P=\dfrac{3}{17}\times 100=17.64\%[/tex]
So, there are 17.64% students received B+ grades.
Why are there so many substances?
Answer:
first conclusion was that the whole world is made up of only 4 elements but as the time passed more elements were discovered... if the world would not contain more elements... you wouldn't be alive.
A chemist wants to examine specific chemical reactions and isolate certain products using a controlled experiment. How would the chemist perform this experiment?
Answer:
in a laboratory
Explanation:
A controlled experiment refers to the one where everything is an experiment except a single variable is held constant. A collection of information is typically taken as a control group, which is generally the ordinary state, and another group is analyzed( such as chemical reaction as per the question) in which all conditions are similar to the control group except for the variable under examination. The main benefit of a controlled experiment is that confusion over the accuracy of the results can be eliminated more easily.
Zinc carbonate dissolves in water to the extent of 1.12 x 10-4 g/L at 25 C. Calculate the solubility product Ksp for ZnCO3 at 25 C.
Answer:
Ksp= 7.98 × 10^-13
Explanation:
According to the question, we are to calculate the solubility constant (Ksp) of Zinc carbonate (ZnCO3) in a dissolved solution.
The equilibrium of the reaction is:
ZnCO3 (aq) ⇌ Zn2+ (aq) + CO32- (aq)
According to this; 1 mole of Zinc carbonate (ZnCO3) dissolves to give 1 mole of Zinc ion (Zn2+) and 1 mole of carbonate ion (CO32-).
This illustrates that:
(Zn2+) = 1.12 x 10-4 g/L
(CO32-) = 1.12 x 10-4 g/L
However, 1.12 x 10-4 g/L is the solubility in mass concentration of ZnCO3, we need to convert it to molar concentration in mol/L by dividing by the relative molar mass of ZnCO3.
To calculate the molar mass of ZnCO3, we say:
Zn (65.4) + C (12) + 03 (16×3)
= 65.4+12+48
= 125.4g/mol.
Hence, molar concentration= 1.12 x 10-4 g/L / 125.4 g/mol
= 8.93 × 10^-7 mol/L.
Therefore;
Zn2+) = 8.93 x 10-7 mol/L
(CO32-) = 8.93 x 10-7 mol/L
Ksp = [Zn2+] [CO32-]
Ksp = (8.93 x 10-7) × (8.93 x 10-7)
Ksp = 7.98 × 10^-13
write the IUPAC name the following
Answer:
1. Chloro(methylchloranuidyl)methane
2. 1-Chloro-3,3-dimethylbutane
3. 2-bromobutane
what is the mass of carbon dioxide which contain the same number of molecules as are contained in 14 gram of oxygen?
Answer:
Mass of CO2 WILL BE ~ 9.33 g
Explanation:
Moles of O2 = 14/18
Let the mass of CO2 be x
Then moles of CO2 will be = x/12
moles of CO2 = moles of O2
x/12 = 14/16
x = 9.33 grams
How many protons, electrons, and neutrons does the following isotope contain?
Answer:
Explanation:
An atom is composed of a nucleus and electrons orbiting around it,and the nucleus itself contains protons and neutrons (with the exception of protium, an isotope of hydrogen with only a proton in the nucleus) because each element contains a specific and unique number of protons, but the number of neutrons can vary,an element, therefore, can have several variants, called isotopes, which differ slightly in the composition of the nucleus,the number of electrons can also change in an atom, giving us positive or negative ions.
=Br-79 has 79 nucleons. 79 protons and neutrons. We know that bromine has 35 protons, and 35 electrons, so all we need to do is subtract. 79 nucleons - 35 protons = 44 neutrons,
Subtract the atomic number from the mass number,the result gives you the number of neutrons in the isotope,look to see if the isotope has a charge, denoted by a superscript number and a plus or minus sign next to it,subtract the charge from the atomic number if the charge is positive,the result is the number of electrons in the isotope,add the absolute value of the charge to the atomic number if the charge is negative,the result is the number of electrons in the isotope.
= 35 from 79 and you will get 44. 44 is the number of neutrons in the Br-79 isotope.
79-Br+, that means:
It’s still a Br (bromine) atom, so it doesn’t change the number of protons //because changing the number of protons, it won’t be bromine anymore//
So bromine atom has 35 protons
So, isotope means many forms of atoms with the same element, which are different from atomic mass (or more clearly, the number of neutrons) → 79 (this number is shown for the atomic mass) - 35 = 44 neutrons
It has 35 protons, 34 electrons and 44 neutrons. The way to figure this out is - the protons of an element never change. So when you say bromine, you look it up on the Periodic table and you see its atomic number (aka # of protons) is 35. It will always be 35 for bromine. Then you take the charge into account. In this case, the charge is +1. Since protons can’t change, electrons must. One more proton equals one less electron. So 34 electrons. The atomic weight of a number (79 in this case) is = # of protons + # of neutrons. So neutrons = 79 - 35 = 44.
Hope this helps!
What is the ph of 0.00035 M KOH
Answer:
13.5
Explanation:
Potassium hydroxide fully ionizes when dissolved in water according to the following equation:
K
O
H
→
K
+
+
O
H
−
Now, let's find the relationship between
K
O
H
and
O
H
−
1
:
1
ratio
⇒
[
K
O
H
]
=
[
O
H
−
]
=
6.7
×
10
−
3
M
In any aqueous solution,
[
H
3
O
+
]
and
[
O
H
−
]
must satisfy the following condition:
[
H
3
O
+
]
[
O
H
−
]
=
K
w
[
H
3
O
+
]
=
K
w
[
O
H
−
]
[
H
3
O
+
]
=
1.0
×
10
−
14
6.7
×
10
−
3
[
H
3
O
+
]
=
1.5
×
10
−
12
M
Now, after finding the concentration of the hydronium ion, the pH of the solution is determined:
p
H
=
−
log
[
H
3
O
+
]
p
H
=
−
log
[
1.5
×
10
−
12
]
p
H
=
11.83
Other Method
Find the pOH using the concentration of the hydroxide ion, then use the formula
p
H
+
P
O
H
=
14
to find the pH.
The -Hasselbalch equation may be used to get the pH of 0.00035 M KOH.
What is the way for calculating the pH ?According to this formula, the pH of a solution is determined by adding the pKa of the acid and the logarithm of the base to acid ratio. KOH has a pKa of 14.0.
Therefore, the following formula can be used to determine the pH of the 0.00035 M KOH solution: pH = 14.0 + log (0.00035/1) pH = 14.0 - 3.46 As a result, the pH of the KOH solution at 0.00035 M is 10.54. Since KOH is a strong base, it completely dissociates in water, forming a solution that is made up of K+ and OH- ions.
Water reacts with hydroxide ions to make hydronium ions (H3O+), which are created when a strong base is introduced. The amount of hydronium ions in the solution rises as a result of this reaction, which lowers the pH of the liquid.
A KOH solution with a pH of 0.00035 M has a value of 10.54, which is higher than the pH of pure water (7.0). This is because when KOH dissociates in water, hydronium ions are produced. A solution's acidity or alkalinity can be determined using the pH of a 0.00035 M KOH solution.
A solution's pH is measured between 0 and 7, with 7 being neutral or alkaline and 0 being acidic. Since 0.00035 M KOH has a pH of 10.54, which is higher than 7, the solution is either basic or alkaline.
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what do you understand by Gas oline
Answer:
It is petroleum-derived product comprising a mixture of liquid aliphatic and aromatic hydrocarbons, ranging between C4 and C12 carbon atoms with the boiling range of 30–225°C
Explanation:
Gasoline is a mixture of paraffins, naphthenes, aromatics and olefins.
Which of the following best describes this sentence?
There were 20 flamingos at the zoo.
Group of answer choices
Qualitative observation
Quantitative observation
Qualitative inference
Quantitative inference
Answer:
i think quantitative observation
Hurricane Donna was one of the most severe hurricanes on record. What empirical evidence could scientists analyze and evaluate to support the statement?
Answer:
The comparison of the damages generated by Hurricane Donna with respect to others. The empirical information that can support this may be the number of homes affected or the cost of repairs after the hurricane has passed until it stops.
Explanation:
Empirical knowledge is the knowledge that it generates from experience and observation, perception tells us how something works and its natural characteristics.
If a scientist assures that it was the most severe hurricane, it is because the scientist is comparing the disasters generated by Hurricane Donna with other ones.
Answer:
I'm not quite sure.....
Explanation:
Which term describes the process of making an economic decision by considering both the advantage and the problems that might arise from the decision
Answer:Cost benefit analysis
Explanation:
Production, distribution, exchange, consumption, saving, and investment of economic resources are all a part of economic decisions. Public and private objectives. Economic choices are made in order to further the interests of both the general public and private persons and organizations (public goals).
The purchase of a device at a specific price is a straightforward illustration of an individual economic decision. This person will have to decide whether it is worthwhile to use his or her limited financial resources to purchase a device. A family's financial decision is virtually analogous, except that it involves more people this time.
The laws of supply and demand are used in the marketplace to guide economic decisions. The term describes the process of making an economic decision as a cost-benefit analysis.
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What is the light transmission of chlorine?
Explanation:
The Absorption of Light by Chlorine, Bromine and their Gaseous Mixtures
Which step should be next in this procedure? List the materials that are needed. Write a conclusion for the experiment. Write a hypothesis for the results. Draw a table for the observations.
Question 9
9. A substance has no definite shape or form.
True
False
Answer:
it us false
Explanation:
air and gas don`t have definite shape
but solid have all definite
Which types of particles are found in the nucleus of the atom?
Answer:
Hope it helps you dude :)
Can someone pls explain this to be step by step:
The density of a substance is 1.03g/cm? What would be the density in mg/mm'?
Answer:
Explanation:
You can do this by doing dimensional analysis.
The first step is to change grams to mg
1000 mg = 1 gram
So the fraction will look like this
1.03 g * 1000 mg/ 1 gram = 1030 mg (the grams cancel out)
Now move onto the volume. The volume is actually 1 cm^3. This becomes 1 cm^3 / 1000 mm^3
So the answer becomes
1030 mg / cm^3 * ( 1 cm^3/1000 mm^3) The cm^3 cancel out
1030 mg / 1000 mm^3
1.030 mg/ mm^3
what do you mean by fractional column?
Answer:
Fractional column is an essential item used in distillation of liquid mixtures so as to seperate the mixture into its component parts, or fractions based on the differences in volatilities.
Explanation:
Air has a mass of 1.2g and a volume of 4,555ml. What is the density
Answer:
Hey there!
Density=Mass/Volume
Density=1.2/4555
Density=2.63e-4g/cm^3
Let me know if this helps :)
HeLp ASAP pls need it rn
Answer:
I'm pretty sure is a mixture
Click the link here to open the atom-building interactive, and click the atom square. Use the interactive to
answer the following questions. Note: Keep all atoms neutral (net charge = 0) for this exercise. Be sure
to select the "plus" sign to expand the element, mass number, and net charge windows.
Make a He atom with a mass of 4. How many protons did you put in the nucleus?
Make a Li atom with a mass number of 7. How many electrons did you place in the outermost orbital
(ring)?
Make a N atom with a mass number of 14. How many neutrons are in the nucleus?
Make a B atom with a mass number of 11. How many electrons did you put in the second orbital (ring)?
Answer:
2 protons, 1 electron, 7 neutrons, and 3 electrons
Explanation:
Make a He atom with a mass of 4. How many protons did you put in the nucleus?
2 protons
Make a Li atom with a mass number of 7. How many electrons did you place in the outermost orbital (ring)?
1 electron
Make a N atom with a mass number of 14. How many neutrons are in the nucleus?
7 neutrons
Make a B atom with a mass number of 11. How many electrons did you put in the second orbital (ring)?
3 electrons
Answer:
2 protons, 1 electron, 7 neutrons, and 3 electrons
Explanation:
Convert each of the following lengths to the units requested.
A. 17.3 m to kilometers.
B. 2.56 m to kilometers
C. 567 dm to meters
D. 5.13 m to millimeters
Answer:
A=0.173 Km
B=0.00256 km
C=56.7 m
D=5130 mm
Explanation:
first we need to know that
[tex]1km=1000m\\\\1dm=0.1m\\\\1000mm=1m[/tex]
so we can form the following
[tex]\frac{1km}{1000m}=1\\\\\frac{0.1m}{1dm} \\\\\frac{1000mm}{1m}[/tex]
so in A
[tex]17.3m\\\\=17.3m*1\\\\=17.3m(\frac{1km}{1000m} )\\\\=0.0173km[/tex]
in B
[tex]2.56m\\\\=2.56m*1\\\\=2.56m(\frac{1km}{1000m} )\\\\=0.00256km[/tex]
in C
[tex]567dm\\\\=567dm*1\\\\=567dm(\frac{0.1m}{1dm} )\\\\=56.7m[/tex]
in D
[tex]5.13m\\\\=5.13m*1\\\\=5.13m(\frac{1000mm}{1m} )\\\\=5130mm[/tex]
Alchemy is the process of trying to turn non-gold metals into gold. It was practiced hundreds of years ago by scientists who believed that with the right amounts of heat or chemical reactions, they could make gold. After years of experiments and observations, gold was never produced. Which best describes the practice of alchemy
Answer:
Alchemy is a practice of making gold from other metals.
Explanation:
Alchemy is a method which is practiced by the ancient scientists of Europe, Africa and Asia trying to produced gold from other metals. This method was failed to produced gold from metals and all scientist suggested that metals can not be converted into gold. Greeks were the people who presented the theory of alchemy in the first few centuries of CE.
Answer:
the answer is Alchemy was scientific because it included observations and experiments
Explanation:
i took the test