Lead is a toxic metal that affects the central nervous system. A Pb-contaminated water sample contains 0.0011% Pb by mass. 13.6 × 10³ ml water contains 150 mg of Pb.
How to calculate the mass of solution ?Given percentage of Pb present in the sample solution is 0.0011%
That means 0.0011 grams of Pb present in the 100g of solution.
So,
= [tex]\frac{0.150\ \text{g Pb} \times 100\ \text{g water}}{0.0011\ \text{g of Pb}}[/tex]
= 13.6 × 10³ g water
What is Density ?The mass per unit volume is called density. Density is represented as D or ρ.
It is expressed as:
[tex]\rho = \frac{m}{V}[/tex]
where,
ρ = Density
m = mass of the object
V = Volume of object
Now put the value in above expression we get
[tex]\rho = \frac{m}{V}[/tex]
[tex]1\ g/ml = \frac{13.6 \times 10^3}{V}[/tex]
V = 13.6 × 10³ ml
Thus from the above conclusion we can say that Lead is a toxic metal that affects the central nervous system. A Pb-contaminated water sample contains 0.0011% Pb by mass. 13.6 × 10³ ml water contains 150 mg of Pb.
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15. What is the mass of mercury in a 250 g fish if the ppm was measured to be 0.23?
Answer: The mass of mercury will be 57.5 micrograms.
The given question deals with Analytical Chemistry where Concentration is asked here.
Concentration: Generally concentration is defined as amount of the substance per unit volume. Concentration is also expressed in parts per million(ppm) when it is a small quantity as in case of mercury content in fish.
Explanation: Given mass of the fish = 250 g,
ppm = 0.23
Now mass of mercury = 0.23 ppm × 250 g
= 0.23/1,000,000 × 250g
=0.23×250/1,000,000 g
= 0.0000575 g
=57.5 micrograms
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Juan measured the temperature of salt water. he then added 273 temperature units to the measured temperature value. which temperature conversion is juan most likely doing?
Celcius to Kelvin
Temperature is defined as the degree or intensity of heat present in a substance It is measured using a thermometer and other equipment. The temperature can be measured in Kelvin, Celsius, and Fahrenheit.
What is Temperature ?Temperature is a physical quantity, thermometers. The units in which can be measured by Celcius, and Fahrenheit. Temperature is measured can be Kelvin,
These units are interconvertible and have certain conversion factors.For example, the conversion factor for Celcius to Kelvin is:0° Celcius = 273 Kelvin
In the given situation, Juan is using the conversion factor of Celcius to Kelvin.Celsius to Kelvin temperature conversion juan most likely to do
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Energy levels of electrons (n) indicates the distance of the energy level from the _______ values of n are positive integers n=1 is closest to the nucleus, and________ in energy
Energy levels of electrons (n) indicates the distance of the energy level from the nucleus values of n are positive integers n=1 is closest to the nucleus, and lower in energy
Any system which is in bounded state is consider to have negative potential energy and negative total energy.
The energy of the electrons rotating in the energy level is given as,
[tex]E_{n} = - 13.6/n^{2} eV[/tex]
[tex]E_{n}[/tex] is energy of the n level.n is the principle quantum number.So, on increasing value principle quantum number (n) the energy of the level is become higher.
The first energy level can contain to 2 electrons , the second energy levels can contain 8 electrons and third energy levels can contain 18 electrons and fourth energy levels can contain 32 electrons
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A 0.500 L solution of 5 M Hydrochloric acid stock solution is used to make a diluted Hydrochloric acid solution of 2.08 M . How much water has to be used to dilute the stock solution
Answer:
0.702 L H₂O
Explanation:
To find the volume of water needed to dilute the stock solution, you need to (1) find the moles of the stock solution (via molarity formula), then (2) find the volume of the diluted solution (via molarity formula), and then (3) find the volume of water needed.
(Step 1)
Molarity (M) = moles / volume (L) <----- Molarity formula
5 M = moles / 0.500 L <----- Insert values
2.5 = moles HCl <----- Multiply both sides by 0.500
(Step 2)
Molarity = moles / volume <----- Molarity formula
2.08 M = 2.5 moles / volume <----- Insert values
(2.08 M) x volume = 2.5 moles <----- Multiply both sides by volume
volume = 1.20 L <----- Divide both sides by 2.08
(Step 3)
Diluted Volume = 1.20 L
Stock Volume = 0.500 L
Water Volume = ? L
Diluted Volume = Stock Volume + Water Volume
1.20 L = 0.500 L + Water Volume
0.702 L = Water Volume
_____ was the first expert system developed to determine the chemical structure of molecules.
Answer:
Dendral was the first expert system developed to determine the chemical structure of molecules.
Classify the electron configurations of neutral atoms based on whether they represent an excited‑state configuration or a ground‑state configuration.
Excited state configuration are 1s²2s²2p⁶3s²3p⁶3d¹⁰4s²4p⁶4d¹ , [Kr] 5s¹ 4d¹⁰ , [He] 2s¹ 2p⁵and Ground state configuration are [Ne] 3s²3p³ , [Ar] 4s¹ 3d⁶.
What is Electronic Configuration ?The electronic configuration of an element describe the symbolic notation that how electrons are distributed in its atomic orbitals.
What is Ground State of electronic configuration ?The ground state electronic configuration of an element describe the arrangement of an atom at its lowest possible energy state.
Cr has the ground state electronic configuration [Ar] 4s¹ 3d⁶.
Ag has the excited state electronic configuration [Kr] 5s¹ 4d¹⁰ .
Thus from the above conclusion we can say that Excited state configuration are 1s²2s²2p⁶3s²3p⁶3d¹⁰4s²4p⁶4d¹ , [Kr] 5s¹ 4d¹⁰ , [He] 2s¹ 2p⁵and Ground state configuration are [Ne] 3s²3p³ , [Ar] 4s¹ 3d⁶.
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Disclaimer: The question was given incomplete on the portal. Here is the complete question.
Question: Classify the electron configurations of neutral atoms based on whether they represent an excited state configuration or a ground state configuration.
Excited State Ground State
Answer Bank:
1s²2s²2p⁶3s²3p⁶3d¹⁰4s²4p⁶4d¹
[Ar] 4s¹ 3d⁶
[Ne] 3s²3p³
[He] 2s¹ 2p⁵
[Kr] 5s¹ 4d¹⁰
(1.) Which neutral atom has the excited or ground state electronic configuration, [Ar] 4s¹ 3d⁶ ? Enter the name of the element.
(2.) Which neutral atom has the excited or ground state electronic configuration, [Kr] 5s¹ 4d¹⁰ ? Enter the name of the element
A sample of a compound is determined to have 1.17 g of carbon and 0.287 g of hydrogen. what is the correct representation of the empirical formula for the compound?
CH3 is the empirical formula for the compound.
A sample of a compound is determined to have 1.17g of Carbon and 0.287 g of hydrogen.
The number of atom or moles in the compound is
1.17 g C X 1 mol of C / 12.011 g C = 0.097411 mol of C.
0.287 g H x 1 mol of H / 1 g H = 0.28474 mol H.
This compound contains 0.097411 mol of carbon and 0.28474 mol of Hydrogen.
So we can represent the compound with the formula C0.974H0.284.
Subscripts in formulas can be made into whole numbers by multiplying the smaller subscript by the larger subscript.
we can divide 0.284 by 0.0974.
0.284 / 0.0974 = 3.
So here, Carbon is one and hydrogen is 3.
We can write the above formula as a CH3.
Hence the empirical formula for the sample compound is CH3.
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When enzyme activity rate has reached stability, an increase in the enzyme concentration will.
When enzyme activity rate has reached stability, an increase in the enzyme concentration will not make any difference in the enzyme rate.
What is an enzyme?Enzyme are proteins that act as biological catalysts.
How is enzyme activity measured?Enzyme activity is measured in micromoles of substrate converted (or product generated) per minute, which represents the rate of reaction catalyzed by that enzyme.
The activity an enzyme catalyzes in a reaction is a measure of how much of it is present. Numerous variables, including temperature, pH, and others, have an impact on the connection between activity and concentration.Every time an enzyme's concentration rises, so does its activity. This is as a result of the availability of additional enzymes to bind to the substrate. The reaction time quickens as a result. Increasing the concentration of the enzyme will quicken the reaction as long as there is a substrate for it to bind to.To learn more about enzyme activity visit:
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When enzyme activity rate has reached stability, an increase in the enzyme concentration will not make any difference in the enzyme rate.
What is an enzyme?
Enzymes are proteins that act as biological catalysts.
How is enzyme activity measured?Enzyme activity is measured in micromoles of substrate converted (or product generated) per minute, which represents the rate of reaction catalyzed by that enzyme.
The activity an enzyme catalyzes in a reaction is a measure of how much of it is present.Numerous variables, including temperature, pH, and others, have an impact on the connection between activity and concentration.Every time an enzyme's concentration rises, so does its activity.This is as a result of the availability of additional enzymes to bind to the substrate.The reaction time quickens as a result.Increasing the concentration of the enzyme will quicken the reaction as long as there is a substrate for it to bind to.To learn more about enzyme activity visit:
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An iron bar at 200°c is placed in thermal contact with an identical iron bar at 120°c in an isolated system. after 30 minutes, both iron bars are at 160°c. if the iron bars were placed in thermal contact in an open system instead of an isolated system, how would the results be different? assume that the room temperature is 25°c.
What kind of defect or dislocation does a carbon in a ti metal lattice represent?
electrical conductivity is the kind of defect or dislocation a carbon in a ti metal lattice represents.
The electrical conductivity of a metal is the result of the movement of charged particles. Atoms of metal elements are electrons in the outer shell of the atom and are characterized by the presence of valence electrons that can move freely around
Staircase dislocations and Lomer-Cottrell dislocations are examples of fixed dislocations. The two main types of movable dislocations are blade dislocations and spiral dislocations. The blade dislocations can be visualized as being caused by the termination of the atomic plane at the center of the crystal.
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Which of the following are exact
numbers? Select all that apply.
Answer:
I believe it would be 30, 100, and 1. You count them, and they're significant figures. The decimals are an estimate and cannot be measure exactly. That is what I've learned, not sure what you're learning but hopefully it helps...
Explanation:
Basic explanation is when you count, that's an exact count. You're not estimating. That's real. But for measuring something, you wouldn't have a precise answer because it could go on forever (like Pi)... this is just what i'm assuming.
Two liquids are in a graduated cylinder - liquid a has a density of 1.004 g/cm3 and liquid b has a density of 0.6223 g/cm3 . assuming that they do not mix, which liquid is on top and which liquid is on bottom? where would you expect to find the plastic cube from question #2 if it is dropped into the graduated cylinder with these two liquids?
Liquid B is expected to be at the top while liquid A is found at the bottom.
What is density?The term density has to do with the ratio of the mass of a substance to its volume. Now given that the density of a substance actually shows how much heavy the substance is, it is not difficult to understand that a material that has a low density will flat at the top of a material that has a lower density.
Here we are told that the two liquids do not mix. If they do not mix then it follows that they must have formed a two phase system in which one is at the top of the other. The one that is at the top must have the lower density.
Thus, liquid B is expected to be at the top while liquid A is found at the bottom. From the density of the plastic cue, the cube will be at the top.
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is generally regarded as one of the most accomplished and influential
scientists in history.
answer - Albert Einstein
explanation -
Albert Einstein is arguably the most influential scientist of the 20th century. His … general theory of relativity changed our understanding of space and time, becoming one of the two pillars of modern physics – the other being quantum mechanics.
According to boyle's law, the pressure of a gas increases as the volume decreases because:
Answer:
according to the law,the pressure would increase if volume has been decreased.
Explanation:
the reason is that,pressure and volume are inversely proportional,if volume has been decreased that means the pressure would increase because decreased volume would create a sort of compacted situation for particles either of a liquid or gas,decreasing volume would bring these particle together, closer to each other because of decreased and since the volume has decreased they dont have enough space,they would end up getting closer to each other most likely to collide, which drastically increase pressure .
The table shows the concentration of a reactant in the reaction mixture over a period of time.
Reactant Concentration
Time Concentration
Os 1.8 M
210 s 1.2 M
450 S 0.8 M
580 S 0.6 M
720 s 0.4 M
What is the average rate of the reaction over the first 450 seconds? (3 points)
Ob
Oc
Od
1.7 x 10-3
1.9 x 10-3
2.0 x 10-3
2.2 x 10-3
The average rate of the reaction over the first 450 seconds -2.2×10⁻³ M/s
What is speed?Speed is defined as the rate of change of the distance moved with time. Mathematically, it can be expressed as:
Speed = distance / time
With the above idea, we can obtain the rate of the reaction as illustrated below:
How to determine the rate of the reaction over the first 45osChange in concentration = 0.8 - 1.8 = -1 MTime = 450 sSpeed = ?Rate = Change in concentration / time
Rate = -1 / 450
Rate = -2.2×10⁻³ M/s
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D is correct for number 2. i just finished
explanation; i got it right
125) How many known elements are on the periodic table?
A) 101
B) 78
C) 118
D) 148
126) The formula for ethanol alcohol is C2HsOH. How many hydrogen atoms are
there?
A) 2
B) 5
C) 6
D) 7
127) The formula for ethanol alcohol is C¿HsOH. How many total atoms are there?
A) 4
B) 7
C) 9
D) 11
128) What is the symbol for Gold?
A) Go
B) Au
C) Sn
D) C
Explanation:
125)118
126)6
127)9
128)Au
There are 118 elements discovered yet and they are included in the periodic table.There are 6 hydrogens in ethanol. Number of total atoms in it is 9. The symbol of gold is Au.
What is periodic table?Periodic table is a classification of elements discovered in nature. There are groups and periods for these elements where groups are vertical columns of elements with similar physical and chemical properties.
There are 118 elements in the periodic table. Thus option C is correct.
Ethanol is a simple alcohol formed by 2 carbons and 5 hydrogens with an OH group. Thus there are total 6 (option C) hydrogens and a total of 9 atoms (option C). Ethanol is widely used in making of alcoholic products.
The chemical symbol of gold is Au. Chemical symbols are elements are derived from their latin names. The latin name of gold is Aurom. Thus it has the symbol Au. Therefore, option B is correct.
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Where is information found concerning acceptable species substitutions for wood materials used in aircraft repair
The list of acceptable species of wood materials used in aircraft structure is found in Table 1-1 on Page 1-2 of AC 43.13-1B.
Which types of wood are used in aircraft repair?Construction of Aircraft with Wood There are four types of wood that are frequently used in the manufacture of aircraft. These include Douglas fir, Sitka spruce, birch, and ash. Additionally, gabon, mahogany, balsa, and pine serve specific purposes. Softwood Sitka Spruce grows in both Canada and the United States of America.
What wood is used for aircraft?Contrary to popular opinion, Howard Hughes' Spruce Goose was made of birch, not spruce, despite the fact that Sitka spruce is the most often used wood in airplanes. Spruce is regarded as the best natural material for building aircraft because it has one of the highest strengths-to-weight ratios.
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pls help!! I need the answer to this ASAP
Answer:
I think the element is carbon and the atomic mass is 12.011
Water will expand more than ____________.
door
air
juice
Answer:
door
Explanation:
door I guess..................
Which amino acid and which atom has most to do with myoglobin’s ability to bind o2?.
The amino acid and which atom which has most to do with myoglobin’s ability to bind o2 is histidine and haemoglobin respectively
What is amino acid?Amino acids simply refers to those molecular substances which combine together to form proteins. However, they are the end products of protein digestion
So therefore, the amino acid and which atom which has most to do with myoglobin’s ability to bind o2 is histidine and haemoglobin respectively
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A student weighs out a 7.24 g sample of , transfers it to a 300. mL volumetric flask, adds enough water to dissolve it and then adds water to the 300. mL tick mark. What is the molarity of zinc chloride in the resulting solutio
The molarity of the zinc chloride solution will be 0.089 M
MolarityMole of 7.24 g ZnCl2 = 7.24/136.286 = 0.5312 mol
Total volume of water used in preparing the solution = 300 + 300 = 600 mL
Molarity of the solution = mole/volume = 0.5312/0.6 = 0.089 M
The molarity of the zinc chloride solution is, therefore, 0.089 M
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The Haber process Select one: a. is used to manufacture ammonia b. transforms nitrogen to other nitrogen-containing compounds c. is used to recover sulfur from underground deposits d. is used to produce nitric acid e. none of these
The Haber process (a) is used to manufacture ammonia.
The Haber process, which artificially fixes nitrogen, is currently the primary industrial method for producing ammonia.
Using a metal catalyst and high temperatures and pressures, the process turns atmospheric nitrogen (N2) into ammonia (NH3) by reacting with hydrogen (H2).
Haber's reaction is - N2 + H2 ------> NH3
The gases (nitrogen and hydrogen) are passed through four beds of catalyst in this conversion, which is normally carried out at pressures above 10 MPa (100 bar; 1,450 psi) and between 400 and 500 °C (752 and 932 °F). Cooling is applied between each pass to maintain a reasonable equilibrium constant.
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Find the density of a substance whose volume is 10.0 mL and whose mass is 5.000 g
Answer:
.5 gm / ml
Explanation:
Density is defined as mass/ volume
so density of this substance is 5 gm / 10 ml = .5 gm/ ml
Please Help!
3/1H + 2/1H → 1/0n + ?
a. 4/4Be
b. 2/1H
c. 3/0n
d. 4/2He
Answer:
I'm pretty sure the answer Is c because I think I remember doing something like that so yeah
In the reaction catalyzed by the pyruvate dehydrogenase complex, the two carbons constituting the acetyl group are
Transferred to the lipoamide by an earlier intermediate in the process.
The pyruvate dehydrogenase complex (PDC) is a mitochondrial multienzyme complex composed of three different enzymes
What reaction is catalyzed by enzyme 2 of the pyruvate dehydrogenase complex ?the pyruvate dehydrogenase complex is the bridge between glycolysis and the citric acid cycle
Five coenzymes are used in the pyruvate dehydrogenase complex reactions: thiamine pyrophosphate or TPP, flavin adenine dinucleotide or FAD, coenzyme A or CoA, nicotinamide adenine dinucleotide or NAD, and lipoic acid.during the reactions catalyzed by the pyruvate dehydrogenase complex, it is first reduced to dihydrolipoamide, a dithiol or the reduced form of the prosthetic group, and then, reoxidized to the cyclic form.Learn more about Pyruvate dehydrogenase complex here:
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Complete the charge balance equation for an aqueous solution of h2co3 that ionizes to hco−3 and co2−3.
The relevant coefficients for each species on the right side of the equation in order to balance the charges.
We can add a coefficient of 2 to HCO³⁻ and a coefficient of 1 to CO3- because the charges must cancel out: H₂CO₃ ⇌ 2HCO³⁻ + CO₃²⁻-
The charges balance is now: No initial charge
Charge total: 2(-1) + (-2) = -4
Due to the balance of the charges, the charge balance equation is as follows: H₂CO₃ ⇌ 2HCO³⁻- + CO₃²⁻.
,Thus, The charge balance equation is as follows: H₂CO₃ ⇌ 2HCO³⁻- + CO₃²⁻.
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A hydrogen bond can occur between:
A. Two hydrogen atoms on different molecules.
B. Two oxygen atom surrounded by hydrogens.
C. The two hydrogen atoms on a water molecule.
D. A hydrogen from one molecule and an oxygen from another molecule.
The combination of a hydrogen atom in a molecule and the oxygen atom in another molecule leads to hydrogen bonding. Option D
How does hydrogen bond occur?For hydrogen bond to occur, hydrogen must be bonded to a highly electronegative atoms in a direct covalent linkage. This accounts for the high boiling point of water.
Thus we can say that a hydrogen bond occurred when a hydrogen from one molecule and an oxygen from another molecule. Option D
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In the combustion of propane: __ C3H8 __ O2 --> __ CO2 __ H2O When the equation is balanced using the smallest whole numbers, the coefficient of O2 will be:
Answer:
1 C3H8 + 5 O2 --> 3 CO2 + 4 H2O
Explanation:
USE PENCIL! Balancing equations typically requires some initial trial and error. Making changes is common.
_ C3H8 __ O2 --> __ CO2 __ H2O
We know we can only have whole molecules, so all number coefficients must be, eventually, whole numbers. It is OK to start with a fraction, but the final must be a shole number. Pick the most complex molecule (either product or reactant) and assign it a coefficient of 1.
1 C3H8 __ O2 --> __ CO2 __ H2O
Now find places for each of the atoms in C3H8 on the product side. 3 carbons means we need 3CO2 molecules, so add a coeffient of 3,
1 C3H8 __ O2 --> 3 CO2 __ H2O
3 CO2 means we need 6 oxygens, so add a coefficient of 3 for the O2:
1 C3H8 + 3 O2 --> 3 CO2 __ H2O
Now find a home for the 8 hydrogens that come from the 1 C3H8. Add 4 to the H2O product:
1 C3H8 + 3 O2 --> 3 CO2 + 4 H2O
This last step added 4 more O to the product side, so we need to adjust the reactant source of O:
1 C3H8 + 5 O2 --> 3 CO2 + 4 H2O
Double check the result:
Element Reactant Product
C 3 3
H 8 8
O 10 10(6+4)
Everything checks.
[Note that one might use a fraction such as 1/2 or 1/3 just to make the balance work. But fractions must be converted to whole numbers for the final equation. For 1/2, multiply all coefficients by 2. By 3 for 1/3, etc.]
What is one off the differences in how the leading and lagging strands of dna molecules synthesize?
The basis of the difference between the leading and lagging strand is that DNA polymerase can join new nucleotides only to the 3' end of the growing strand.
The leading strand is the new DNA strand that continually extends from 5' to 3'. On the lagging strand, Okazaki fragments develop and are linked by DNA ligase activity. DNA polymerase can only attach new nucleotides to the 3' end of the developing strand, which forms the basis of the distinction between the leading and lagging strands.
Therefore, "DNA polymerase can link additional nucleotides exclusively to the 3' end of the developing strand" is the appropriate response.
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Which identifies an oxidation-reduction reaction?
a double replacement reaction
a neutralization reaction
a reaction in which oxidation numbers change
a reaction in which no electrons are transferred
The statement that identifies an oxidation-reduction reaction is a reaction in which oxidation numbers change (option C).
What is a redox reaction?A redox or oxidation-reduction reaction is a chemical reaction in which some of the atoms have their oxidation number changed.
In a chemical reaction that involves oxidation and reduction, the oxidation number of the involved ions either decreases or increases.
Therefore, the statement that identifies an oxidation-reduction reaction is a reaction in which oxidation numbers change.
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