An unknown element X has the following isotopes: ²⁵X (80.5% abundant) and ²⁷X (19.5% abundant). What is the average atomic mass in amu of X?
Answer:
25.4 amu
Explanation:
Step 1: Given data
Mass of the isotope ²⁵X (m²⁵X): 25 amuAbundance of the isotope ²⁵X (ab²⁵X): 80.5 % = 0.805Mass of the isotope ²⁷X (m²⁷X): 27 amuAbundance of the isotope ²⁷X (ab²⁷X): 19.5% = 0.195Step 2: Calculate the average atomic mass of X
We will use the following expression.
m = m²⁵X × ab²⁵X + m²⁷X × ab²⁷X
m = 25 amu × 0.805 + 27 amu × 0.195
m = 25.4 amu
Neil Bohr's model of the atom suggested that electrons are found in distinct paths. Question 11 options: True False
Answer:
true
Explanation:
Calculate the volume, in milliliters, of a 0.470 M KOH solution that should be added to 5.250 g of HEPES (MW = 238.306 g/mol, pKa = 7.56) to give a p
Answer:
17.13mL
Explanation:
Complete question:
to give a pH of 7.32.
Hepes is a weak acid. When HEPES reacts with KOH its conjugate base, HEPES⁻ is produced:
HEPES + KOH → HEPES⁻
Now when you have in solution both the weak acid and conjugate base a buffer is produced. The equation that relates pKa and pH of a buffer is H-H equation:
pH = pKa + log [HEPES⁻] / [HEPES]
Where [] could be taken as the moles of each specie.
Replacing:
7.32 = 7.56 + log [HEPES⁻] / [HEPES]
-0.24 = log [HEPES⁻] / [HEPES]
0.57544 = [HEPES⁻] / [HEPES] (1)
Now, moles of 5.250g of HEPES is:
Mass HEPES:
5.250g * (1mol / 238.306g) = 0.02203 moles HEPES.
That means:
0.02203 moles = [HEPES⁻] + [HEPES] (2)
Replacing (2) in (1):
0.57544 = 0.02203 moles - [HEPES] / [HEPES]
0.57544[HEPES] = 0.02203 moles - [HEPES]
1.57544[HEPES] = 0.02203 moles
[HEPES] = 0.01398 moles HEPES.
And [HEPES⁻] = 0.02203 moles - 0.01398 moles =
0.00805 moles of HEPES⁻
As HEPES⁻ is produced from HEPES and KOH, if we add 0.0805 moles of KOH, we will have in solution 0.00805 moles of HEPES⁻ and 0.01398 moles of HEPES.
To obtain 0.00805 moles of KOH from a 0.470M KOH, you need to add:
0.00805 moles KOH * (1L / 0.470mol) = 0.01713L of 0.470M KOH =
17.13mLComplete each of the definitions with the appropriate phrase. Precision means that ___________measurements are close to____________ Accuracy means that___________ measurements are close to_____________
Answer:
Precision means that independent measurements are close to each other.
Accuracy means that independent measurements are close to a known or accepted value.
Explanation:
Accuracy refers to how close the measurements of a measurement system are to the true value while precision refers to how close the measurements are to each other. In other words, accuracy is the closeness of the value of one or more independent measurements to a true value, and precision is the closeness of two or more values of several measurements to each other.
Both are independent of each other, that is to say that the results in the values of a measurement can be precise and not exact, and vice versa.
So:
Precision means that independent measurements are close to each other.
Accuracy means that independent measurements are close to a known or accepted value.
Give the names of the cation in each of the following compounds: a. CuS b. Ag2SO4 c. Al(ClO3)3 d. CO(OH)2 e. PbCO3.
Answer:
a. Cu2+ (Copper (II) ion ) b. 2Ag+ ( Silver ion) c. Al3+ (Aluminium (III) ion) d. Co2+ ( Cobalt (II) ion) e. Pb2+ ( Lead (II) ion )
Explanation:
Cations are positively charged ions.
In the question given;
CuS , known as Copper (ii) Sulphide, has Cu2+ (Copper (II) ion ) as the Cation.
Ag2SO4, Known as Silver Sulfate, has 2Ag+ ( Silver ion) as the Cation.
Al(ClO3)3, known as Aluminium Chlorate, has Al3+ (Aluminium (III) ion), as the Cation.
Co(OH)2, known as Cobalt(II) Hydroxide, has Co2+ ( Cobalt (II) ion) , as the Cation.
PbCO3, known as Lead(II) Carbonate, has Pb2+ ( Lead (II) ion ), as the Cation.
a knowledge of life science is essential for botanists, forest technicians ,park rangers and health care workers true or false
Answer: True
Explanation:
I took the test
Answer:
T
Explanation:
Trust i took the test :p
Categorize each property as either physical or chemical.
Physical Properties
Chemical Properties
melting point
color
density
flammability
corrosiveness
electrical
reactivity with acids
hardness
Answer:
Physical properties are the properties of a substance that can observed and measured without altering the identity of the substance. Examples of physical properties according to the above question are color, hardness, malleability, electrical conductivity, density, melting point.
Chemical properties on the other hand are the properties of a substance that describes the ability of the substance to undergo chemical reactions based on its composition. Examples include reactivity with acids, flammability.
In other words, to identity a chemical property of a substance we check its ability to be change into a different state via chemical reaction. Rusting of iron is a good example of chemical property.
So therefore, categorizing the properties we have;
Physical properties Chemical Properties
Melting point Flammability
Color Reactivity with acids
Density Corrosiveness
Electrical conductivity
Hardness
Answer:
Physical: Melting Point, Color, Conductivity, Boiling Point
Chemical: Susceptibility to rust, flammability
Explanation:
Which of the following options correctly describe physical and chemical properties? A- A phase change always occurs when a physical property is measured B- When a chemical property is measured, the substance being observed is converted to a different substance or interacts with another substance. C- A chemical property of a substance can be observed without changing its composition or interacting with another substance. D- A physical property can be observed without a chemical reaction.
Answer:
The correct options are B and D
Explanation:
A physical property is a property (of any substance) that can be observed without the substance undergoing any change in identity nor does it require a chemical reaction to determine. For example, colour and size are physical properties that are part of the identity of a substance and can/must be observed without a substance undergoing any change or chemical reaction. This explanation makes option A wrong and option D right.
A chemical property of a substance is the property that relies on the ability of that substance to undergo a chemical reaction/interaction with another substance to form a new/different substance. For example, ability of a substance to react with an acid (to form a different substance) is a chemical property. This explanation makes option C wrong and option B correct.
Convert a density of 1,235 kg/m3 to grams per cubic centimeter
Answer:
Density, [tex]d=1.235\ g/cm^3[/tex]
Explanation:
It is given that, the density is 1,235 kg/m³.
We need to convert the density to g/cm³.
We know that,
1 kg = 1000 g
1 m = 100 cm
[tex]1235\ kg/m^3=1235\ \dfrac{kg}{m^3} \\\\=1235\times \dfrac{1000\ g}{(100\ cm)^3}\\\\=1.235\ g/cm^3[/tex]
So, the density is [tex]1.235\ g/cm^3[/tex].
4.731 * 10 ^ - 7 / 5.7 * 10 ^ 3 express in scientific notation
Answer:
8.3 × 10¯¹¹
Explanation:
4.731×10¯⁷ ÷ 5.7×10³
The above expression can be simplified as follow:
4.731×10¯⁷ ÷ 5.7×10³
Recall
a^m ÷ a^n = a^(m – n)
4.731×10¯⁷ ÷ 5.7×10³ = (4.731 ÷5.7) × 10^(–7 – 3)
4.731×10¯⁷ ÷ 5.7×10³ = 0.83 × 10¯¹⁰
4.731×10¯⁷ ÷ 5.7×10³ = 8.3×10¯¹ × 10¯¹⁰
Recall
a^m × a^n = a^(m + n)
8.3×10¯¹ × 10¯¹⁰ = 8.3 × 10^(–1 + –10)
8.3×10¯¹ × 10¯¹⁰ = 8.3 × 10^(–1 – 10)
8.3×10¯¹ × 10¯¹⁰ = 8.3 × 10¯¹¹
Therefore,
4.731×10¯⁷ ÷ 5.7×10³ = 8.3 × 10¯¹¹
Use the pop-up menus to label the following statements as either True of False.
1. Hypochlorous acid is an oxidizing agent.
2. Concentrated acetic acid is corrosive.
3. Methylene chloride is flammable.
4. Methylene chloride is a probable human carcinogen.
5. Pipets that contain only water can be disposed of in the trash.
Answer:
1 True
2. True
3. True
4. True
5. False
Explanation:
1. Hypochlorous acid (HOCl) is a weak acid that forms when chlorine dissolves in water, and is partially dissociated, forming hypochlorite. HOCl is considered a strong oxidizing agent responsible for the killing action of germs in chlorine solutions.
2. Acetic acid is also known as ethanoic acid. It has a distinctive sour taste and pungent smell, and is generally considered a weak acid. in a concentrated form, acetic acid can be corrosive.
3/4 . Methylene chloride is an organochloride compound with the formula CH2Cl2. It is a colorless, volatile liquid with a moderately sweet aroma is widely used as a solvent. It is normally stable, non-flammable and non-explosive when mixed with air at temperatures below 100 °C, but its vapor is flammable only when present in relatively high concentrations of about 14% to 22% in air. Research shows that it is very much possibly carcinogenic, and it has been linked to cancer of the lungs, liver, pancreas, breast cancer and salivary gland cancer in laboratory animals.
5. Laboratory and medical waste are not to be disposed in the trash with regular wastes, as they are potentially toxic. Special disposal methods and agencies exists to take away such wastes.
A student was asked to separate a mixture of chemicals. The weight of each component within the mixture is as follows: potassium bromide 2.53g and 0.760g barium sulfate. What is the percentage of barium sulfate within the mixture?
Answer:
a
Explanation:
f
The percentage of barium sulphate within the mixture is 23.1 %.
We have a mixture of barium sulfate and potassium bromide.
We have to determine the percentage of barium sulfate within the mixture.
What is a Mixture ?A mixture is a material made up of two or more different chemical substances which are not chemically bonded to one another.
According to the question -
Mass of barium sulfate = 0.760 g
Total mass of mixture = 0.760 + 2.53 = 3.29 g
Therefore, the percentage of barium sulfate within the mixture -
0.760/3.29 x 100 = 23.1 %
Hence, the percentage of barium sulphate within the mixture is 23.1 %.
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The solar wind is made up of ions, mostly protons, flowing out from the Sun at about 400 km/s. Near Earth, each cubic kilometer of interplanetary
space contains, on average, 6 x 10^15 solar-wind ions.
How many miles of ions are in a cubic kilometer of near- Earth space?
Answer:
There are [tex]6\times 10^{12}[/tex] miles of ions in a cubic kilometer of near-Earth space.
Explanation:
In this context, we must be clear on stating that words miles is a synonym for thousands. In other words, the question may be rewritten to this form: How many thousand of ions are in a cubic kilometer of near-Earth space? In engineering notation, a thousand is represented by:
[tex]x = 10^{3}[/tex]
As we know the average quantity of solar-wind ions in a cubic kilometer of interplanetary space near Earth, we need to make quick conversion to determine the quantity of miles of ions by this formula:
[tex]y = n\cdot 10^{-3}[/tex]
Where:
[tex]n[/tex] - Quantity of solar-wind ions, measured in units.
[tex]y[/tex] - Quantity of solar-wind ions, measured in thousands (or miles).
If we know that [tex]n = 6\times 10^{15}\,units[/tex], then:
[tex]y = (6\times 10^{15}\,units)\cdot \left(10^{-3}\,\frac{miles}{unit} \right)[/tex]
[tex]y = 6\times 10^{12}\,miles[/tex]
There are [tex]6\times 10^{12}[/tex] miles of ions in a cubic kilometer of near-Earth space.
Which of the following is true about critical analysis of promotional claims?
a. It is necessary because consumers generally do not need to purchase goods.
b. Advertisements intend to mislead consumers about the goods they portray.
c. It prevents consumers from purchasing unnecessary goods.
d. It is essential because advertisements always contain false information.
Answer:
Which of the following is true about critical analysis of promotional claims?
a. It is necessary because consumers generally do not need to purchase goods.
b. Advertisements intend to mislead consumers about the goods they portray.
c. It prevents consumers from purchasing unnecessary goods. Is Correct
d. It is essential because advertisements always contain false information.
Critical analysis is an important aspect of the evaluation of the needs and demands. It is an integrated part of promotional claims to prevent unnecessary purchasing. Thus, option c is correct.
What is a promotional claim?The promotional event is used in advertising to characterize the benefits and advantages of the services and products so as to persuade consumers and customers to buy the services and goods. The advertisements use claims to attract audiences.
It is a marketing strategy to increase sales and attract customers by offering various deals and services. The critical analysis of the promotional claim must be done to avoid the unnecessary purchasing of the goods and services by the consumers.
Therefore, option c. the unnecessary buying of the goods can be prevented by critical analysis.
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please answer this question
Answer:
false, true, false - In reality stirring increases the speed of dissolving.
Answer:
False
True
False
Explanation:
1.It does take the shape of the container (has cohesive and adhesive properties)
2. It is a good solvent as in it, lots of salts are able to dissolve.
3. Stirring increases the speed of dissolving.
Given the ion C2O4-2- , what species would you expect to form with each of the following ions?1. K+ _____2. Cu2+_____3. Bi3+_____4. Pb4+______5. NH4+______6. H+______
Answer:
1. K₂C₂O₄
2. CuC₂O₄.
3. Bi₂(C₂O₄)₃
4. Pb(C₂O₄)₂.
5. (NH₄)₂C₂O₄
6. H₂C₂O₄
Explanation:
Hello,
In this case, since the oxidation states are exchanged according to the naming rules, the resulting species are shown below:
1. K₂C₂O₄
2. CuC₂O₄ (here, the +2 of copper and -2 of C₂O₄, are simplified).
3. Bi₂(C₂O₄)₃
4. Pb(C₂O₄)₂ (here, the +4 of lead and -2 of C₂O₄, are simplified).
5. (NH₄)₂C₂O₄
6. H₂C₂O₄
Regards.
What kind of substances can you not heat on a Bunsen burner?
Answer:
Substances which are non heat-resistant and volatile organic liquid with flammable vapor.
Explanation:
Bunsen Burner are used as a source of fire in the laboratory for heating up substances. Extra care however should be taken during heating in order to prevent fire or other forms of accidents.
Heating of mind heat resistant substances should be frowned at as the substances may get heated up and melt thereby exposing the liquid substances which may be flammable to fire thereby causing fire outbreak.
Heating of volatile organic liquid with flammable vapor should also be discouraged to prevent fire accidents.
PLEASE HELP WILL GIVE BRAINLIEST!!!
How is a light bulb related to radiation?
A. The light emitted by a light bulb is a form of radiation that occurs when the filament heats up and its thermal emission gains enough energy to move into the visible spectrum.
B. Light bulbs do not have anything to do with radiation.
C. As light is emitted from the filament, the energy in the metal is replaced as lightbulbs absorb background radiation. This prevents the filament from burning out quickly but the radiation cannot be used as power so electricity is still required for the lightbulb to work.
D. A light bulb emits radiation when its filament is burned out and can longer emit light. This makes it important to remove dead lightbulbs as soon as they wear out.
Answer:
The light emitted by a light bulb is a form of radiation that occurs when the filament heats up and its thermal emission gains enough energy to move into the visible spectrum.
Explanation:
Light bulbs contain a filament which is heated up electrically. When this filament is heated up,energy in the form of heat is imparted to the electrons in the filament.
This thermal excitation of electrons ultimately leads to emission of light in the viable spectrum. This light is now radiated through a light bulb.
Jia observes that adding a solution of sodium hydroxide to a clear liquid turns the liquid pink. She makes a hypothesis about why the liquid changed color. Which characteristic is least important for her hypothesis to have?
The question is incomplete, the complete question is;
Jia observes that adding a solution of sodium hydroxide to a clear liquid turns the liquid pink. She makes a hypothesis about why the liquid changed color.
Which characteristic is least important for her hypothesis to have?
A)ability to be tested
B)based on the opinion of her classmates
C)ability to be proven incorrect
D)based on her current knowledge
Answer:
B)based on the opinion of her classmates
Explanation:
A hypothesis is a supposition or tentative explanation put forward based on minimal evidence. It sometimes sets the pace for further investigation.
Hypothesis is always based on empirical observation and not on popular opinion, hence the opinion of Jia's classmates is least important in Jia's formulation of a hypothesis.
Answer:
B) based on the opinion of her classmates
Explanation:
edge 2023
What is the volume of a sample of mercury having a mass of 1.0 kg if the density of mercury is 13.5g/cm3?
Answer:
volume = 74.07 cm³Explanation:
The volume of a substance given the density and mass can be found by using the formula
[tex]volume = \frac{mass}{Density} [/tex]
From the question
Density = 13.5 g/cm³
We must first convert the mass from kg to g
1kg = 1000 g
mass of mercury = 1000 g
Substitute the values into the above formula and solve
That's
[tex]volume = \frac{1000}{13.5} [/tex]
We have the final answer as
volume = 74.07 cm³Hope this helps you
Copper slowly reacts with oxygenIs this a physical or chemical change?
Answer:CHEMICAL
Explanation:
it cannot go back to its original state and it reacts.
graph results on a grid x 0, 10, 20, 30, 40, 50, 60, 70 and y 0,2,6,15,6,3,1,0
Determine the number of significant figures in each of the following measurements:________.
(a) 0.0000003 cm
(b) 2901 g
(c) 40.2 g
(d) 56 mL
Answer:
(a) 1.
(b) 4.
(c) 3.
(d) 2.
Explanation:
Hello,
(a) In this case, we do no take into account the zero digits before the first nonzero digit which is three, therefore it has one significant figure.
(b) In this case, we consider all the given figures since they are all after the first nonzero digit, therefore it has four significant figures.
(c) In this case, we consider all the given figures since they are all after the first nonzero digit including the decimal place, therefore it has three significant figures.
(d) In this case, we consider all the given figures since they are all after the first nonzero digit, therefore it has two significant figures.
Regards.
a cube is 4 cm on each size .what is it’s volume?
Answer:
64cm^3
Explanation:
[tex]s = 4cm\\V = s^3\\\\V = 4^3\\V =4\times 4\times 4\times 4\\Volume = 64cm^3[/tex]
1. What is the name of the covalent compound CCl4?2. What is the name of the covalent compound N2O5?
The name of the covalent compound CCl₄ is carbon tetracloride while that of N₂O₅ is dinitrogen pentoxide.
What is a covalent compound?Covalent compound has a covalent bond which is defined as a type of bond which is formed by the mutual sharing of electrons to form electron pairs between the two atoms.These electron pairs are called as bonding pairs or shared pair of electrons.
Due to the sharing of valence electrons , the atoms are able to achieve a stable electronic configuration . Covalent bonding involves many types of interactions like σ bonding,π bonding ,metal-to-metal bonding ,etc.
Sigma bonds are the strongest covalent bonds while the pi bonds are weaker covalent bonds .Covalent bonds are affected by electronegativities of the atoms present in the molecules.Compounds having covalent bonds have lower melting points as compared to those with ionic bonds.
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which of the following is an example of a combustion reaction ?
A. photosynthesis in plants
B. cellular respiration in humans
C. mixing of vinegar and baking soda
D. release of carbon dioxide on heating limestone
Answer:
D. release of carbon dioxide on heating limestone
Answer:
The guy up there is wrong cause i literally just took this test and the answer is B. cellular respiration in humans
Explanation:
What will be the charge of the ion formed from each of these atoms ?
Si14, As33, Mg12, Rb37, F9, Ge32, Sn50
Answer:
Si14- Si^4+
As33- As^3-
Mg12- Mg^2+
Rb37- Rb^+
F9- F^-
Ge32- Ge^4+
Sn50- Sn^2+, Sn^4+
Explanation:
The elements shown in the answer have their common ions written beside them.
Silicon mostly forms positive ions in oxyacids and complex ions. Arsenic mostly forms its anion. Magnesium forms only the +2cation just as rubidium only forms the +1 cation. The fluoride ion is F^- while tin may for a +2*or +4 cation. Germanium usually forms the +4 cation.
What is the hydrogen ion concentration of a solution with pH 5.60?
Answer:options
Explanation:
What is the term for "anything that takes up space and has mass"?
O A. Electron
B. Water
O c. Matter
O D. Atom
SUBN
Billy is running at a rate of 8 m/s West he ran a total distance of 400 m how long does it take him to complete the distance
Answer:
50 Seconds
Explanation:
400 Divided By 8 Is 50
Answer:
50
Explanation:
Its 50 because 400/8=50