Answer:
It takes 86 days take to cover half of the lake
Explanation:
In the day #1, the amount of the algae is X,
In the day #2 is 2X
In the day #3 is 2*2*X = X*2²
...
In the day #n the amount of the algae is X*2^(n-1)
Assuming X = 1m³. In the day 87, the area infected was:
1m³*2^(87-1)
7.74x10²⁵m³ is the total area of the lake
the half of this amount is 3.87x10²⁵m³
The time transcurred is:
3.87x10²⁵m³ = 1m³*2^(n-1)
Multiplying for 5 in each side:
ln (3.87x10²⁵) = ln (2^(n-1))
58.9175 = n-1 * 0.6931
85 = n-1
86 = n
It takes 86 days take to cover half of the lakeHELPHELPHELPHELPHELPHELPHELP
Answer:
C
Explanation:
increasing T (knowledge of direct proportion and Inverse proportion)
What happens as you decrease the temperature of a solution?
A.
The number of solute particles increases.
B.
The number of solute particles decreases.
C.
The rate of dissolution increases.
D.
The rate of dissolution decreases.
E.
The temperature has no effect on the rate of dissolution.
Answer:
D is the answer
Explanation:
Both the appearance and cooking times of food items are affected by the way a piece of food is:
Select one:
a. examined.
b. tenderized.
c. purchased.
d. cut.
Answer:
D.
cut.
Explanation:
Both the appearance and cooking times of food items are affected by the way a piece of food is cut. Thus option D is correct.
what are the types of food ?
Food has an important role in both culture and cuisine of every country, Different types of food combine to form culinary delights which can bring people together
Food is obtained from both plants and animals where Plants are the primary producers in the food pyramid and all organism directly or indirectly obtain food from plants.
Herbivorous animals get their food from their plant ecosystem where Some animals, obtain food by hunting other animals while others depend on decaying matter of plants and animals which are called decomposers like bacteria, fungi.
Food offers variety forms depend upon climatic conditions and availability and depend on the different factors like Physical determinants ,Biological determinants, Economical determinants.
Thus option D is correct.
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Help me pleaseeeeeeeeeee
Answer:
I think A I hope it's A
Explanation:
hsjsjakkska
A gaseous mixture contains 5.0 moles of nitrogen and 10.0 moles of helium . What is the total pressure if the temperature is 25 degrees C and the volume is 3.0 L? a) 122 atm
B) 56 atm
d) 2.0 atm
C)3.0 atm
Answer:
A) 122 atm
Explanation:
PV = nRT
Solve for P --> P = nRT/V
n = 10.0 mol + 5.0 mol = 15.0 mol
R = 0.08206 L atm / mol K
T = 25 + 273 = 298 K
V = 3.0
P = (15.0)(0.08206)(298) / (3.0) = 122 atm
A transition metal complex has a a maximum absorbance of 610.7 nm. What is the crystal field splitting energy, in units of kJ/mol, for this complex? Express your answer using at least three significant figures.
The crystal field splitting energy for the transition metal complex with a maximum absorbance of 610.7 nm is approximately 53.8 kJ/mol.
The absorbance maximum at 610.7 nm corresponds to the energy of the absorbed light, which can be calculated using the equation E = hc/λ, where E is the energy, h is Planck's constant, c is the speed of light, and λ is the wavelength. Rearranging the equation to solve for the crystal field splitting energy (Δ), we get Δ = hc/λ. Plugging in the values, Δ = (6.626 x 10^-34 J·s * 3.00 x 10^8 m/s) / (610.7 x 10^-9 m). The result is approximately 3.23 x 10^-19 J. To convert this to kJ/mol, we need to multiply by Avogadro's number (6.022 x 10^23) and divide by 1000, giving us a crystal field-splitting energy of approximately 53.8 kJ/mol. This value is obtained by calculating the energy of the absorbed light using the equation E = hc/λ, where E is the energy, h is Planck's constant, c is the speed of light, and λ is the wavelength. By rearranging the equation and plugging in the values, we can determine the crystal field splitting energy, which represents the energy difference between the d-orbitals in the complex.
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Complete and balance the following redox equation in acidic solution using the smallest whole number coefficients. What is the coefficient of SnO₂ in the balanced equation? Sn + HNO₃ → SnO₂ +NO₂ +H₂O a. 2
b. 1
c. 4
d. 3
The coefficient of SnO₂ in the balanced equation is c. 4.
To balance the redox equation in acidic solution, we need to ensure that the number of atoms of each element and the total charge are balanced on both sides of the equation.
By assigning appropriate oxidation numbers to each element and considering the changes in oxidation states, the balanced equation is as follows:
Sn + 4HNO₃ → SnO₂ + 4NO₂ + 2H₂O
In the balanced equation, the coefficient of SnO₂ is 4, indicating that 4 molecules of SnO₂ are produced. This balanced coefficient ensures that the number of tin (Sn) atoms and oxygen (O) atoms are equal on both sides of the equation. Therefore, the correct answer is c. 4.
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The elements C and Se have the same electronegativity value, 2.55. Which of the following claims about the compound that forms from C and Se is most likely to be true?
a. The compound is likely to be an ionic compound.
b. The compound is likely to be a covalent compound.
c. The compound is likely to be a metallic compound.
d. The compound is likely to be an organic compound.
Carbon (C) and Selenium (Se) having the same electronegativity value of 2.55 is likely to form a (b) covalent compound.
An electronegativity value is the measure of the ability of an atom to attract shared electrons towards itself when they are chemically bonded with another atom.
Brief Information about C and Se:
Carbon (C) - Carbon is the 6th element on the periodic table. It is a non-metallic element that can be found in all known life forms. Carbon has 4 valence electrons, and it can either lose or share electrons to attain a stable electron configuration.
Selenium (Se) - Selenium is a non-metal element that belongs to group 16 of the periodic table. It has 6 valence electrons, and it can either lose or share electrons to attain a stable electron configuration. It is not found in its elemental form in nature and it is found in trace amounts in soils, rocks, and water.
Based on the above information, the following claim about the compound that forms from C and Se is most likely to be true: Option b. The compound is likely to be a covalent compound.
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If a calorimeter used for an experiment had been made out of a heat-conducting material, such as metal, rather than styrofoam, a non-heat conducting metal, would the measured calorimeter constant be larger or smaller? Explain your answer.
If a calorimeter made of a heat-conducting material, such as metal, is used instead of a non-heat conducting material like Styrofoam, the measured calorimeter constant would be smaller. This is because a calorimeter made of a heat-conducting material would allow heat to be transferred more efficiently between the system being studied and the surroundings, resulting in less heat being absorbed by the calorimeter itself.
When conducting experiments involving heat transfer, a calorimeter is used to measure the heat exchanged. The calorimeter constant represents the amount of heat absorbed or released by the calorimeter for a given temperature change. A calorimeter made of a heat-conducting material, like metal, would conduct heat more effectively from the system to the surroundings. This means that a larger proportion of the heat generated by the system would be transferred away from the calorimeter, resulting in less heat being measured by the calorimeter itself. Consequently, the measured calorimeter constant would be smaller compared to using a non-heat conducting material like Styrofoam, where more heat would be retained within the calorimeter.
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How many moles is 80.0 g of calcium?
Answer:
Here we were given the weight of Ca as 80g
and the atomic mass of carbon is 40u(molar mass)
using the formula
n=W/Mwhere w is weight and m is molar mass
80/40
=2
therefore, there are 2 moles in 80g of calcium
if you mix equal volumes of 1 m hf and 1 m koh, is the resulting solution acidic , basic, or neutral?
The resulting solution is neutral when equal volumes of 1 M HF and 1 M KOH are mixed.
When equal volumes of a strong acid and a strong base are mixed, the resulting solution is neutral. In this case, 1 M HF (hydrofluoric acid) and 1 M KOH (potassium hydroxide) are both strong acids and bases, respectively.
When the HF and KOH react, they undergo a neutralization reaction:
HF + KOH → KF + H2O
The reaction between a strong acid and a strong base forms a salt (KF in this case) and water. Since KF is a neutral salt and water is neutral, the resulting solution will be neutral.
When equal volumes of 1 M HF and 1 M KOH are mixed, the resulting solution is neutral.
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Which is a characteristic of a physical change?
a
The chemical bonds in the substance are unchanged.
b
The change cannot be seen.
c
The molecules all move at the same speed.
d
The substance has reacted with another substance.
3.4
Why is this cocktail not the perfect medication to treat infections by these
bacteria?
Answer:
many bacteria are resistant to penicillin and other β-lactam antibiotics - some bacteria have beta-lactamase enzymes and are able to break down the antibiotics - as a result, many drugs are combined with other drugs that are β-lactamase inhibitors.
Explanation:
Quizlet
Why is it dangerous to have electric appliances near you when you are taking a bath?
Answer:
Because water conducts electricity, so if an electrical current were to meet the water while you're in there taking a bath, you would essentially be surrounded by a huge conductor.
Identify the orbital containing the electron removed in each ionization. Enter a subshell designation, such as 3p or 5s.
a. 1st
b. 2nd
c. 3rd
The orbitals are;
a. 1st - 4s
b. 2nd - 4s
c. 3rd - 3d
What is the orbital from which the first, second and third electrons are removed from the transition elements?First, second, and third electrons from the 4s orbital are frequently removed from transition elements before any electrons from the 3d orbital. This is due to the fact that the energy levels of the 4s and 3d orbitals are quite similar and the energy level of the 4s orbital is marginally lower.
According to the Aufbau principle, electrons fill the lowest possible energy levels first in the electron configuration of transition elements before migrating to higher energy levels. As a result, electrons fill the 4s orbital first, followed by the 3d orbital, with the first two electrons.
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(Please help 15 points the assignment is late) (multiple questions) (everything is virtual task )
Part 1 What do you think will happen when an effervescent tablet is placed in the water under each inverted glass?
Part 2 Note the changes in the water level and the air space in both glasses, and write down your observations.
Part 3 Did your prediction match your observation?
Part 4. When a substance easily dissolves in a liquid, it has high solubility in that liquid. When a substance does not easily dissolve in a liquid, it has low solubility in that liquid. Solubility of a gas in water describes how well the liquid can “hang on” to gas, instead of releasing it into the air. Based on the results of your experiment, do you think that CO2 has a higher solubility in hot water or cold water? Why?
Part 5 Soda pop is carbonated with CO2. Mark puts one bottle of soda pop in the refrigerator and leaves the other out in the hot sunlight. After one hour, he opens both bottles. Which bottle will likely have more fizzing and bubbles? Why?
Part 6 One result of climate change is that ocean temperatures are increasing. If the temperatures continue to rise, what effect will that have on the oceans’ ability to retain CO2? How might this change affect the atmosphere?
The dissolution of gases in water is exothermic therefore oceans will dissolve less CO2 as their temperatures rise.
What is effervescence?
The term effervescence refers to the rise of a gas in a system or simply put, it is the evolution of gas. When an effervescent tablet is placed in the water under each inverted glass, a gas will rise in each glass.
The air space in the hot glass is greater than the air space in the cold glass We can see that the gas has a lower solubility in hot water than in cold water. This is because, solubility of gases is exothermic.
The bottle that is left in the hot sun will have more fizzing because the CO2 does not dissolve owing to the higher temperature.
The rise in ocean temperature means that the oceans will dissolve less CO2 in the future and reduce the CO2 holding capacity of the oceans.
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Thallium-201 has a half-life 73 hours. If 4.0 mg of thallium-201 disintegrates over a period of 6.0 days and 2 hours, how many milligrams of thallium-201 will remain?
Answer:
[tex]\huge\boxed{\sf 1.0 \ mg}[/tex]
Explanation:
Half-life = 73 hours
Disintegration period = 6 days 2 hours = (6*24) hours + 2 hours
= 144 hours + 2 hours
= 146 hours
No. of Half lives = Disintegration period / Half-lifeNo. of Half lives = 146 hours / 73 hours
No. of Half lives = 2
Hence, there are 2 half lives passed in 6 days 2 hours.
Amount of thallium-201 left after first half-life:
= 4.0 mg / 2
= 2.0 mg
Amount of thallium-201 left after second half-life:
= 2.0 mg / 2
= 1.0 mg
Hence, the amount of thallium-201 left after 6.0 days and 2 hours is 1.0 mg.
[tex]\rule[225]{225}{2}[/tex]
Hope this helped!
~AH1807Jet streams can cause warmer air temperatures on coastal land areas when
A. a cold jet stream occurs
B. a warm jet stream occurs
C. the tide changes direction
Jet streams can cause warmer air temperatures on coastal land areas when the tide changes direction.
What are jet streams?Jet streams are short bands of high wind that travel across the globe from west to east.
On earth, the location of the jet stream is in the latitude of the tropopause.
Two polar jet streams are present near the north and south poles.
Two subtropical jet streams are present, closer to the equator,
These make the Earth's four principal jet streams.
Thus, the correct option is C.
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which of the following is true of carbon? select all that are correct. group of answer choices it can form a maximum of four covalent bonds with other elements. it can form a maximum of three covalent bonds with other elements. it is highly electronegative. it can form both polar and nonpolar bonds. it can only form polar molecules.
Based on the given options, the following statements are true of carbon: It can form a maximum of four covalent bonds with other elements and It can form both polar and nonpolar bonds.
Carbon is an element with atomic number 6, meaning it has six protons in its nucleus. It has four valence electrons, which are the electrons involved in bonding with other atoms.
Carbon's electron configuration allows it to form four covalent bonds by sharing its valence electrons with other atoms. This property is known as tetravalency and is a fundamental characteristic of carbon.
Additionally, carbon can form both polar and nonpolar bonds depending on the atoms it is bonded to and the electronegativity difference between them.
When carbon bonds with atoms of similar electronegativity, such as hydrogen, the bond is nonpolar because the electrons are shared equally. However, if carbon bonds with atoms of higher electronegativity, such as oxygen or nitrogen, the bond becomes polar due to the unequal sharing of electrons.
In summary, carbon can form a maximum of four covalent bonds with other elements due to its tetravalent nature. It is not highly electronegative itself but can form both polar and nonpolar bonds depending on the atoms it is bonded to. Therefore, the correct statements are:
It can form a maximum of four covalent bonds with other elements.
It can form both polar and nonpolar bonds.
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PLEASE HELP ME NO LINKS
Answer: I don’t think the answer is A or C. Maybe B.
The word chemosynthesis means
the synthesis of organic compounds by bacteria or other living organisms using energy derived from reactions involving inorganic chemicals, typically in the absence of sunlight.
Explanation:
The concentration of sugar in Coke is approximately 10%, or 100 ppt. If you drink
a single can of coke, which holds 355 ml, how much sugar have you consumed?
Answer:
35.5g of sugar
Explanation:
To solve this question we must assume the density of coke = Density of water = 1g/mL
Thus, in a single can of coke, the mass is 355g. Now, the 10% of this coke is sugar. That means the amount of sugar you are consuming is:
355g * (10/100) = 35.5g of sugar
10/100 = 10%
2.50 Kilojoule (2.5 Kj) is the same amount of energy in calories?
A) 598 cal.
B) 2720 cal.
C) 0.598 cal.
D) 105 cal.
2.50 Kilojoule (2.5 Kj) is the same amount of energy in calories as (A) 598 cal.
To convert kilojoules (Kj) to calories, you can use the conversion factor of 1 kilocalorie (kcal) = 4.184 kilojoules (Kj).
Here, 2.50 Kilojoules (2.5 Kj) is the amount of energy, we can convert it to calories as follows:
2.50 Kj * (1 kcal / 4.184 Kj) = 0.598 kcal
Since 1 kilocalorie (kcal) is equal to 1000 calories (cal), we can further convert:
0.598 kcal * 1000 cal/kcal = 598 cal
Therefore, the same amount of energy as 2.50 Kilojoules (2.5 Kj) is 598 calories.
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What is the standard units of mass, length and time in the (a) CGS system (b) SI system
Explanation:
a. CGS system: centimetre as the unit of length, the gram as the unit of mass, and the second as the unit of time
b. SI system: metre as the unit of length, the kilogram as the unit of mass, and the second as the unit of time
1. Why is the timing of tides predictable?
A. because winds are predictable
B. because the moon’s path is predictable
C. because ocean water density is predictable
D. because the sun’s movements are predictable
Answer:
Because the moon's path is predictable
Explanation:
The moon affects the tides
consider a thin film of of soapy water (n = 1.33) on plexiglas. since light is a wave, there are many thicknesses of this film that will result in constructive interference.
When light passes through a thin film of soapy water (n = 1.33) on plexiglass, there are several thicknesses of this film that will result in constructive interference.
Due to the light being a wave, it can create a constructive or destructive interference pattern.The thickness of the thin film of soapy water can be calculated by using the equation 2nt = mλ where n is the refractive index of the medium, t is the thickness of the film, m is the order of interference, and λ is the wavelength of the incident light.
If the thickness of the film satisfies the above equation, the light waves will interfere constructively, resulting in a bright spot.
The order of interference determines the location of the bright spot and is indicated by an integer value (m = 0, 1, 2, 3...).
The reason why soapy water forms a thin film on plexiglass is due to the adhesion and cohesive forces between the two.
The thickness of the film can be controlled by changing the concentration of soap in water or the angle of incidence of the light.
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The table gives the concentrations of C2H4O(g)C2H4O(g) as a function of time at a certain temperature for the reaction shown.
C2H4O(g)⟶CH4(g)+CO(g)C2H4O(g)⟶CH4(g)+CO(g)
Verify that this is a first-order reaction by plotting ln[C2H4O]ln[C2H4O] versus time and determining the value of the rate constant.
[C2H4O] (M)Time (min)0.08600.000.046558.00.035583.00.0274107.00.0174150.0
_____________min^-1 ?
The required answer for the value of the rate constant, k, is 0.009 min-1.
Explanation: For verifying if the reaction is first order, the graph of ln [C2H4O] versus time will be plotted.The given data can be used for calculating the ln [C2H4O] as given below:ln [C2H4O] = ln [0.0860] = -2.45ln [C2H4O] = ln [0.0465] = -3.06ln [C2H4O] = ln [0.0355] = -3.33ln [C2H4O] = ln [0.0274] = -3.60ln [C2H4O] = ln [0.0174] = -4.05Now, we will plot a graph between ln [C2H4O] and time on a sheet of paper or in excel. From the graph, we will get a straight line The graph obtained is a straight line which confirms that the given reaction is first order.
To determine the value of rate constant, k, we will use the formula:ln [C2H4O] = -kt + ln [C2H4O]0Where,[C2H4O] = Concentration of ethylene oxide at time t [C2H4O]0 = Initial concentration of ethylene oxide at t = 0 k = Rate constant of the reaction t = Time period of the reactionNow, we will use the given data to determine the value of k:ln [0.0860] = -k × 0 + ln [0.0860] => k = 0ln [0.0465] = -k × 8 + ln [0.0860]=> k = 0.012ln [0.0355] = -k × 3 + ln [0.0860]=> k = 0.008ln [0.0274] = -k × 7 + ln [0.0860]=> k = 0.010ln [0.0174] = -k × 50 + ln [0.0860]=> k = 0.009Thus, the value of the rate constant, k, is 0.009 min-1.
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Question 19 (3 points)
If the density of the earth was 11.0 g/mL instead of its measured value of 5.51 g/mL, the force of gravity would
be twice what it is at sea level. If the earth's density was twice than its actual density, then in pounds per
square inch at sea level the earth's atmosphere in British units would be equal to:
a) 7.35 psi b) 14.7 psi c ) 29.4 psi d) 44.1 psl e) 98.8 psi
Answer:
c ) 29.4 psi
Explanation:
If the density of earth was twice than its actual density which is 5.51 g/mL, then at sea level the atmospheric pressure of earth in British units would be equal to 29.4 psi because increase of gravity, increase occurs in the atmospheric pressure. If we double the gravity of earth by double of the earth density, so the weight of that same mass of air will be double which leads to the doubling of the atmospheric pressure at the sea level.
Select the correct answer.
What data points do we combine to make the integrated rate law?
a) initial concentration and time
B) concentration at some later time, time, and rate constant
C) initial concentration, concentration at some later time, and time
D) initial concentration, concentration at some later time, time, and rate constant
Answer:
b???
Explanation:
Answer:
Pretty sure it A.
Explanation:
I just thought that cause what exactly does 'some later time' mean?
A 0.100 M oxalic acid, HO2CCO2H, solution is titrated with 0.100 M KOH. Calculate the pH when 25.00 mL of oxalic acid solution is titrated with 35.00 mL of NaOH. Ka1 = 5.4 × 10−2 and Ka2 = 5.42 × 10−5 for oxalic acid
A 0.100 M oxalic acid, HO₂CCO₂H, solution is titrated with 0.100 M KOH. Calculate the pH when 25.00 mL of oxalic acid solution is titrated with 35.00 mL of NaOH. Ka1 = 5.4 × 10−2 and Ka2 = 5.42 × 10−5 for oxalic acid is 1.94.
Oxalic acid is a dicarboxylic acid with the chemical formula HO₂CCO₂H, with a pKa1 of 1.25 and a pKa2 of 4.14. A titration is a process in which a solution of known concentration is added to a solution of unknown concentration until the equivalence point is reached.
The goal of a titration is to determine the concentration of the unknown solution. A 0.100 M oxalic acid solution is titrated with 0.100 M KOH. The pH is calculated when 25.00 mL of oxalic acid solution is titrated with 35.00 mL of NaOH. Ka1 = 5.4 × 10−2 and Ka2 = 5.42 × 10−5 for oxalic acid. Here is how to calculate the pH when 25.00 mL of oxalic acid solution is titrated with 35.00 mL of NaOH:
Step 1: Calculate the moles of oxalic acid
moles of oxalic acid = concentration x volume
moles of oxalic acid = 0.100 M x 0.025 L
moles of oxalic acid = 0.0025 mol
Step 2: Calculate the moles of NaOH
moles of NaOH = concentration x volume
moles of NaOH = 0.100 M x 0.035 L
moles of NaOH = 0.0035 mol
Step 3: Determine which species is in excess
0.0025 mol of oxalic acid reacts with 0.0025 mol of KOH
0.0010 mol of oxalic acid reacts with 0.0035 mol of KOH
0.0010 mol of oxalic acid is consumed in the reaction
The excess moles of NaOH = 0.0035 - 0.0010 = 0.0025 mol
Step 4: Calculate the concentration of the remaining OH- ions
Concentration of OH- ions = moles of OH- ions / volume
Concentration of OH- ions = 0.0025 mol / 0.060 L
Concentration of OH- ions = 0.0417 M
Step 5: Calculate the concentration of H+ ions
Ka1 = [H+][C₂O₄₂-]/[HC₂O₄-]
5.4 x 10^-2 = x^2 / (0.100 - x)
Assuming that x is much smaller than 0.100, x = [H+] = 0.115 M
Step 6: Calculate the pH
pH = -log[H+]
pH = -log(0.115)
pH = 1.94
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Jack has a rock. The rock has a mass of 14g and a volume of 2cm3. What is the density of the rock?
Answer:
The density is 7 g/cm^3
Explanation:
The formula for density is p=m/V. Where p is the density, m is mass, and V is the volume. 14/2=7.