The half life of radioactive iodine 137 is 8 days 0.0866 iodine nuclei are necessary to produce an activity of 1.0 micro Ci
Here given data is half life of radioactive iodine 137 = 8days
Activity of iodine is = 1.0micro Ci
Radioactive decay is the process by which an unstable atomic nucleus loses energy by radiation and the material containing unstable nuclei is considered radioactive
The interconnection between the decay constant and half-life of any sample can be given by the expression are
T1/2 = (0.693/R); T1/2 = 8
8 = 0.693/R; R=0.0866 R=0.693×1.0/t1/2 = 0.0866
0.0866 iodine nuclei are necessary to produce an activity of 1.0 micro Ci
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Forensics:
roshni, a forensic scientist, has ruled out several different drugs when testing a substance found in a car. She suspects that the substance is cocsine, what should roshni do next?
1-Perform a confirmatory test
2-Put the substance in a bag, label it, and send it to a DEA office
3-Confer with a colleague about her suspicions.
4-Collect a blood sample and see if it also contains the same substance
Since she suspects that the substance is cocsine, the thing that she should do next is option 1-Perform a confirmatory test.
How the Evidence Is Collected?The way that Drug evidence is collected is that from any crime scene, evidence is obtained, photographed, packaged, documented as well as been sent for analysis and then the forensic scientist will carry out the Analysis.
Since the evidence has been sent to Roshni, all she has to do is to carry out the confirmatory test to see if the drug is what she suspected.
Therefore, Since she suspects that the substance is cocsine, the thing that she should do next is option 1-Perform a confirmatory test.
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how would you distinguish between hydrogen and carbon dioxide being evolved from a reaction?
Answer:
I don't understand snap the equation and send it
For a hydrogen atom, calculate the energy of the photon that would be emitted for the orbital transition of n(initial) = 5 to n(final) = 3. The Rydberg constant is 1.09678 x 10⁷ m⁻¹.
The energy of the photon is 1.5 * 10^-19 J
What is the Bohr model?According to the Bohr model of the atom, the atom is arranged in energy levels. It is possible for an electron to transition from a lower to a higher energy level by the gain of energy. The energy that is gained must be equal to the difference in energy between the lower and the higher energy levels of the atom.
No we know that we could use the Rydberg formula to obtain the wavelength of the photon that is emitted when an electron moves from a higher to a lower energy level with the emission of the energy that was taken in.
Thus;
1/λ = RH (1/n^2 final – 1/n^2 initial)
RH = 1.09678 x 10⁷ m⁻¹
n final = 3
n initial = 5
1/λ =1.09678 x 10⁷ (1/3^2 – 1/5^2)
1/λ = 1.09678 x 10⁷ (0.11 – 0.04)
λ = 1302 nm
E = hc/ λ
E = 6.6 * 10^-34 * 3 * 10^8/1302 * 10^-9
E = 1.5 * 10^-19 J
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Calculate the energy of an electron at n=2 in butadiene.
The energy of an electron at n=2 is determined as -3.4 eV.
What is energy level an electron?The energy level of an electron is the fixed distances from the nucleus of an atom where electrons may be found.
Energy of an electron at a known energy levelThe energy of an electron at a known energy level can be calculated using the following formula as shown below.
En = -13.6/n²
where;
n is the energy level of the electronSubstitute the given parameters and solve for the energy of the electron at the given energy level.
En = (-13.6)/(2²)
En = -3.4 eV
Thus, the energy of an electron at n=2 is determined as -3.4 eV.
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Question 5
The process by which a gas condenses is referred to as
exothermic.
endothermic.
ectodermic.
exotic.
Density measurements can be used to analyze mixtures. For example, the density of solid sand (without air spaces) is about 2.84 g/mL. The density of gold is 19.3 g/mL. If a 1.00 kg sample of sand containing some gold has a density of 3.10 g/mL (without air spaces), what is the percentage of gold in the sample?
The percentage of gold in the sample if a 1.00 kg sample of sand containing some gold has a density of 3.10 g/mL is 9.83%.
Let S be the solid sandy mass which is inside the blend
Let G be the gold mass in such a blend
We have to find the percent G by mass
Mixture density can be calculated as
= total blend mass / total blend volume
= 3.10 g/mL
Mixture sum is
S + G = 1 Kg. = 1000g
Complete mixing volume = sand volume + gold volume
Complete mixing volume can be calculated as
=[tex](\frac{sand mass}{sand density} ) + (\frac{gold mass }{gold density} )[/tex]
Total mixture volume:-
[tex]= (\frac{S}{2.84} ) + (\frac{G}{19.3} )\\\\= \frac{(19.3 S + 2.84 G)}{54.812 mL} \\\\Mixture Density = \frac{mass mixture}{mixture volume}\\ \\= 3.10 \frac{g}{mL}[/tex]
⇒ [tex]3.10 = \frac{1000 g}{ \frac{(19.3 S + 2.84 G)}{54.812 mL}}[/tex]
[tex]19.3 S + 2.84 G = 17681\\\\When S+ G = 1000 g\\\\Solving equation:[/tex]
⇒[tex]19.3 S + 2.84 G = 17681[/tex]
∴ [tex]S + G = 1000 g[/tex]
⇒ 19.3 S + 2.84 = 17681
⇒ -2.84 S - 2.84 = -2840
________________________
⇒ 16.46 S = 14841
⇒ S = 901.7g Sand
Given,
⇒ S + G = 1000
⇒ G = 1000 - 901.7 g
⇒ G = 98.3 g Gold
Percentage of gold in the solution is
(98.3/1000) × 100 = 9.83%
Thus, we concluded that the percentage of gold in the sample if a 1.00 kg sample of sand containing some gold has a density of 3.10 g/mL is 9.83%.
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How many moles of N are in 0.207 g of N₂O?
Number of moles of N in 0.207 g of N₂O= 0.0094
We are starting with 0.207g of N₂O in this instance. Let's use the molar mass, which is 44.013 g/mol, to convert that to moles.
(1 mol N₂O / 44.013 g N₂O) x 0.207 g
⇒ 0.00470 mol N₂O.
Having reached moles of nitrogen monoxide, we must now determine how many moles of nitrogen there are. We can see that there is a subscript of 2, indicating that there are two moles of nitrogen for every mol of nitrogen dioxide. You might think of it in terms of food; there are two pieces of bread for every sandwich.
In order to obtain moles of N, let's multiply the amount of moles of N₂O by 2.
(2 mol N / 1 mol N₂O )x 0.00470 mol N₂O = 0.0094 mol N.
Hence, Number of moles of N in 0.207 g of N₂O will be 0.0094.
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Science Investigatory Project title ideas
Explanation:
What noise pollution affecting local fauna...what harmful particulates are in the air we breath?
Toxic Coliforms in drinking water? Is light pollution affecting diurnal plants? Chlorine is toxic, Why is it in our tap water?
The density of mercury is 13.6 g/mL. What is this density in lb/ft3? (1 kg =
2.2046 lb; 1 in = 2.54 cm (exact); 1 mL = 1 cm3) [This problem MUST be solved all in one
string.]
The density of mercury is 13.6 g/ml, then the density in Ib/ft³ is 21.57 Ib/ft³.
What is density?Density can be defined as the measure to how much matter is contained in a specific volume. It can also be defined as a expression of relationship between the mass and the volume.
Dimension of density are ML⁻³
1 kg = 2.2046, 1 ml = 1 cm³
Then, 13.6 g/ml = 13.6 x 2.2046 x 2.54
= 76.16 Ib/cm³ = 21.57 Ib/ft³
Thus, the density of mercury is 13.6 g/ml, then the density in Ib/ft³ is 21.57 Ib/ft³.
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Can the individual substances in a homogeneous mixture be physically separated from each other?
Answer:
No
Explanation:
They are bonded on a molecular level and a chemical process must be used to separate
What mass of mercury contains the same number of atoms as 90.15g of helium?
4.5g of mass of mercury contains the same number of atoms as 90.15g of helium.
What is mercury?With the atomic number 80 and the symbol Hg, mercury is a chemical element. Formerly known as hydrargyrum, which is a combination of the Greek terms hydor (water) and argyros), it is also known as quicksilver (silver). The only other element that is known to be liquid under these conditions is the halogen bromine, however metals like caesium, gallium, and rubidium melt just above ambient temperature. Mercury is a heavy, silvery d-block element.
All around the world, deposits of mercury, primarily in the form of cinnabar, are found (mercuric sulfide). Cinnabar, either natural or manufactured mercuric sulfide, is ground to create the crimson pigment vermilion.
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Mg in chlorophyll, C55H72MgN4O5 (the green pigment in plant cells)
Express your answer using five significant figures. Determine the percent, by mass, for Mg
The percent by mass of Magnesium (Mg) in chlorophyll is 2.69%.
How to calculate percent by mass?The percent by mass of an element in a compound can be calculated by dividing the atomic mass of the element by the molar mass of the compound multiplied by 100.
The molar mass of chlorophyll is as follows: 12(55) + 1(72) + 24 + 14(4) + 16(5) = 660 + 72 + 24 + 56 + 80 = 892g/mol
Percent mass of Mg = 24/892 × 100
Percent mass of Mg = 0.0269 × 100
Percent mass of Mg = 2.69%
Therefore, the percent by mass of Magnesium (Mg) in chlorophyll is 2.69%.
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Periodic trends answer key chemistry 10th grade
Trends in modern periodic table are:
variation of valency, atomic size , metallic properties and electronegativity
Valency - number of valence electrons . Elements of each group have same number of valence electrons. So, they have the same valency.
Atomic size- It is distance from the centre of the nucleus to the valence shell of the atom.
Along the period – Atomic radius decreases as effective nuclear charge increases . It pulls valence electrons closer to the nucleusDown the group – Atomic radius increases because new shells are added , thus the distance between nucleus and valence electrons increases.Metallic properties -
Along the period – Metallic character decreases because tendency to lose valence electrons decreases due to the increasing nuclear charge.Down the group – As the distance between nucleus and outermost electron increases, nuclear pull decreases. This increases the tendency of an atom to lose valence electrons, thus metallic character increases.Electronegativity-
Along the period – Electronegativity increases as the tendency to gain electrons in valence shell increases due to increasing nuclear charge. Down the group – Since distance between the nucleus and valence shell increases, nuclear pull decreases. This decreases tendency of atom to gain an electron, thus electronegativity decreases.So we can conclude that periodic trends are specific patterns which are present in the periodic table, that illustrate different aspects of a certain element
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What is the density of a piece of metal that weighs 12 g and has a volume of 500 mL?
Answer:
0.024 g/mL
Explanation:
The denisty of a substance is a ratio comparing its mass per every 1 unit of volume. Therefore, if you have been given a mass in grams and a volume in milliliters, the unit for denisty (in this case) is g/mL.
Density = ? grams / ? mL
Density = 12 g / 500 mL
Density = 0.024 g/ 1 mL = 0.024 g/mL
when liquid water loses energy, a change in state or chemical identity occurs. This is an example of a chemical or physical change?
Answer:
Physical change
Explanation:
Because there may be or may not be change in state,shape size.When water is heated it come to a state of vapour
Which factor affects the temperature of ocean water?
depth
salinity
number of organisms
amount of dissolved gases
The factor affecting the temperature of ocean water among the given options is depth of the ocean.
The temperature of ocean water varies with the depth. Ocean is divided into the three layers depending on the depth. In the ocean, solar energy reflects in upper surface and rapidly gets absorbed with the depth. Upper layer has depth of around 500 m and temperature 20°C - 25°C.
Second layer is thermocline layer with relatively low temperature of water. It indicates that, the deeper you go into the ocean, less sunlight is there. Therefore, deeper oceans are colder.
Deep ocean water is around 90% of the volume of oceans. It has uniform temperature of around 0-3°C.
Temperature and depth are related in such a way that the temperature decreases when the depth increase.
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Answer:
It is A. DepthExplanation:
Hope this helps
My water bottle contains 500 grams of water, H2O. How many moles of water is this?
Answer:
18g6.02×1023molecules=500gx. 18 g 6.02 × 10 23 molecules = 500 g x .
Explanation:
Calculate the number of O atoms in 0.994 g of CaSO4 · 2H2O.
A calcium sulfate crystal weighing 0.150 grams contains 0.00523 moles of oxygen.
White crystalline calcium sulfate, or CaSO4, is a material. Calcium sulphate is hydrate in the mineral or natural substance known as gypsum. As a food additive, calcium sulfate serves as a thickener, anti-caking agent, dough conditioner, dough strengthener, flour treatment agent, and yeast food. It is a thin, odorless powder that is white or white yellow.
Crystallized calcium sulfate mass = m = 0.150 g
Crystallized calcium sulfate's molecular mass is M = 172 g/mol.
Magnesium nitrate moles are equal to n=0.150/172 g/mol = 0.000872 mol.
6 moles of oxygen atoms make up 1 mole of the calcium sulfate crystal. The calcium sulfate crystal will then have 0.004446 moles.
A calcium sulfate crystal weighing 0.150 grams contains 0.00523 moles of oxygen.
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Which point would map onto itself after a reflection across the line y = –x?
The point that would map onto itself after a reflection across the line y = –x is (4, –4). The correct option is d.
What is a map?A point would have to be on the line in the first place for it to map onto itself following a reflection over the line.
To calculate the point on the given line, just substitute the x-values of the given points and solve for y.
There are three different x-values: -4, 0, and 4
Substituting these into y = -x
x = -4 ⇒ y = -(-4) = 4 → (-4, 4)
x = 0 ⇒ y = -(0) = 0 → (0, 0)
x = 4 ⇒ y = -(4) = -4 → (4, -4)
Therefore, the correct option is d, (4, –4).
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The question is incomplete. Your most probably complete question is given below:
(–4, –4) (–4, 0) (0, –4) (4, –4)
Mary studies plants. Which branch of science dose she work in?
Answer:The branch pf science that Mary works in is botany because botany is the study of plants.
Express each of the following numbers in exponential notation:SHOW YOUR WORK
1) 10,000
2) 0.0001
3) 10,000,000,000
4)0.000 000 000 000 001
5)400,000
Answer:
1 a
2 b
3 c
4 d
5 e
Explanation:
i know is corret
f Earth suddenly weighed twice as much as it currently does, how would this change the tides? Explain.
Answer:
yes and no
Explanation:
mostly yes because of the gravity but we would de dead
As the weighed of the earth doubled, gravity also increases. So, there will be fewer or no high tides.
What is gravity? The force that pulls items toward the centre of a planet or other entity is called gravity. All of the planets are kept in orbit around the sun by gravity.Gravity applies to everything that has mass. Gravity is stronger for objects with higher mass. Along with distance, gravity weakens as well.The gravitational pull of two things becomes stronger the closer they are to one another. The mass of the Earth is what creates gravity. The combined gravitational force of all of its mass acts on the mass in your body. What gives you weight is that. The moon is maintained in its orbit around Earth by gravity, as are the planets in their orbits around the sun. Ocean tides are a result of the moon's gravitational effect on the oceans. The stuff that stars and planets are comprised of is pulled together by gravity to form them.To learn more about gravity, refer to
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The percent by mass of oxygen in H4P2O7
The percent by mass of oxygen in H₄P₂O₇ is 62.92%.
How to calculate percentage by mass?The percentage by mass of an element in a compound can be calculated by dividing the atomic mass of the element by the molar mass of the compound multiplied by 100 as follows:
% by mass = atomic mass of O/molar mass of H₄P₂O₇ × 100
The molar mass of H₄P₂O₇ can be calculated as follows:
1(4) + 31(2) + 16(7) = 178g/mol
Percent by mass of oxygen = (112g/mol ÷ 178g/mol) × 100
Percent by mass of oxygen = 62.92%
Therefore, 62.92% is the percent by mass of oxygen.
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A canister with fixed volume at 97.2 kPa and 23.0°C is
to a pressure of 1.88 atm. What is the final
in the canister in degrees Celsius?
compressed
temperature
The final temperature of the canister is 312.76 degrees celsius.
The relation between temperature and pressure is given by the Gay Lusaac’s Law.
According to this law at constant volume, pressure is directly proportional to the temperature.
Mathematically it is as follows,
Pressure (P) ∝ Temperature(T)
P = K T
P/T = K(constant)
Thus the ratio of P/T will remain the same if volume remains constant.
So, P1/T1 = P2/T2
Here P1= initial pressure of the canister = 97.2 kPa = 0.95 atm
P2 = Final pressure of the canister = 1.88 atm
T1 = Initial temperature = 23 c = 296 K
T2 = Final temperature = ?
Putting these values
0.95/296 = 1.88/T2
T2 = 585.76 K or 312.6°C.
Thus, the final temperature of the canister is 312.76 degrees celsius.
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Part C
How many grams of H₂ are needed to produce 12.13 g of NH3?
Grams of H[tex]_{2}[/tex] are needed to produced 12.13 g of NH[tex]_{3}[/tex] are 2.13 g
The balanced chemical equation is :
N[tex]_{2}[/tex] + 3H[tex]_{2}[/tex] ------> 2NH[tex]_{3}[/tex]
H = 1 g/mol and N =14 g/mol
NH[tex]_{3}[/tex] = 17 g/mol =
6g of H[tex]_{2}[/tex] ( 3×2) = 34 g of NH[tex]_{3}[/tex] (2× 17)
mass of hydrogen in coumpond ( % mass ) = 6 / 34
= 0.1764 or 17.64%
mass of H[tex]_{2}[/tex] required = % mass × mass of ammonia
= ( 0.1764 × 12.13 ) g
2.13 g
Thus , Grams of H[tex]_{2}[/tex] are needed to produced 12.13 g of NH[tex]_{3}[/tex] are 2.13 g
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What Is The hypothesis for,What Effect Does Using Plant Food Have On Plant Growth?
Answer: If the amount of fertilizer applied to plants is increased, then plant growth (height) will increase. As the amount of fertilizer increases the plant growth increases.
Explanation: It's correct
A student wants to measure the volume of a rock. The student should measure
the volume using?
Answer:
To measure the volume of a large rock, fill a glass measuring cup up to one half with water. Put your large rock in and measure the new water level. Subtract the original half cup volume of water and the difference is the volume or space that your rock takes up.
Answer:
if the rock is small use a measuring cylinder
Explanation:
what is the smallest alkyne
Answer:
Cyclooctyne (C8H12) is the smallest cycloalkyne capable of being isolated and stored as a stable compound
Explanation:
hope this helps
Percocet contains oxycodone at varying strengths. Every strength also contains 325
mg of oxycodone per tablet. If the dose is not to exceed 3.9 g of oxycodone
daily, what is the maximum number of Percocet tablets a patient can take daily?
12 tablets maximum number of Percocet tablets a patient can take daily
Percocet is a prescription medicine used to treat the symptoms of acute pain and moderate-to-severe pain percocet may be used alone or with other medications percocet belongs to a class of drugs called Analgesics, Opioid Combos every strength also contains 325 this is the weakest dose of Percocet and is what most doctors will start with to help avoid side effects like respiratory depression this dosage is also used to gradually reduce Percocet dosage after dependence has developed, and to limit withdrawal symptoms percocet is a pain reliever for moderate to severe symptom over dose of percocet show side effect on body thats why 12 tablets maximum number of Percocet tablets a patient can take daily.
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Two of most unique elements on the periodic table are hydrogen and helium. What makes them so unique and removed from the other groups on the periodic table?
A:Unlike all other elements, hydrogen and helium are gases
B:Unlike all other elements, hydrogen and helium are not considered metals
C:Unlike all other elements, hydrogen and helium only have a maximum of 2 valence electrons
D:Unlike all other elements, hydrogen and helium have very limited properties
What makes hydrogen and helium so unique and removed from the other groups on the periodic table is that unlike all other elements, hydrogen and helium only have a maximum of 2 valence electrons (option C).
What properties of hydrogen and helium makes them unique?Hydrogen and Helium are two elements in the periodic table. They are the lightest elements in the periodic table.
Also, they both exist as gases at room temperature and are the two most common elements in the universe.
However, hydrogen and helium are removed from other groups of the periodic table. Thisis because hydrogen and helium atoms only have two electrons and the outermost energy level is the first energy level, hence, there can only be two valence electrons.
Therefore, what makes hydrogen and helium so unique and removed from the other groups on the periodic table is that unlike all other elements, hydrogen and helium only have a maximum of 2 valence electrons.
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