The uncertainties of the delta measurements and the uncertainty of the atomic weight derivedfrom the best measurement of isotopic abundances constrain the number of significant figures in theatomic-weight values of the upper and lower bounds. For carbon, the fifth digit after the decimal pointis uncertain because of the uncertainty value of 0.000 027. Therefore, the number of significant digitsin the atomic-weight value is reduced to four figures after the decimal point. The Commission may rec-ommend additional conservatism and reduce the number of significant figures further. For the lowerbound of carbon, 12.009 635 is truncated to 12.0096. For an upper bound, the trailing digit is increasedto ensure the atomic-weight interval encompasses the atomic-weight values of all normal materials. Inthe case of carbon, the upper bound is adjusted from 12.011 532 to 12.0116 to express four digits afterthe decimal point. The lower and upper bounds are evaluated so that the number of significant digits ineach is identical. If a value ends with a zero, it may need to be included in the value to express therequired number of digits. The following are examples of lower and upper atomic-weight bounds foroxygen that could be published by the Commission in its various tables.
---------------------------
Extracted from" Atomic weights of the elements 2009 (IUPAC Technical Report)"
Explain what would happen to the air temperature at Riverdale School over the course of the
day if the groundwater system were used.
Answer:
Air temperature increases.
Explanation:
The air temperature at Riverdale School increases if the groundwater system were used because this system uses very huge amount of water than the other system. By using more molecules having the same temperature, the thing with more molecules has more total kinetic energy or thermal energy than the thing with fewer molecules so that's why air temperature of the school is increases.
How was Bohr's atomic model different from those of previous scientists?
Answer:
Bohr placed the electrons in distinct energy levels. Rutherford described the atom as consisting of a tiny positive mass surrounded by a cloud of negative electrons. Bohr thought that electrons orbited the nucleus in quantized orbits. Also, rutherfords was just a hypothesis while Bhor took the time to make his an experiment
Use what you have learned to match the parts of the
Someone help!!!!FAST
sentences.
The mantle
is both solid and molten.
The core
is the outermost layer.
The part that includes land and water
is called the crust.
The crust
is under the crust.
Answer:
the crust is the outermost layer
Explanation:
the mantle is under the crust, the core is the innermost layer
land and water.is for crust-mantle. contain semi-molten iron and nickel please make the question clear
Answer:
answer in picture
Explanation:
Thiamine hydrochloride (vitamin B1 hydrochloride, HC12- H17ON4SCl2) is a weak acid with Ka 5 3.4 3 1027. Sup- pose 3.0 3 1025 g of thiamine hydrochloride is dissolved in 1.00 L of water. Calculate the pH of the resulting solution. (Hint: This is a sufficiently dilute solution that the autoion- ization of water cannot be neglected.)
Answer:
pH = 6.76
Explanation:
Ka = 3.4x10⁻⁷; 3.0x10⁻⁵g
The molarity of the vitamin B1 -Molar mass: 327.268g/mol- solution is:
3.0x10⁻⁵g * (1mol / 327.268g) = 9.167x10⁻⁸M
The Ka expression is:
Ka = 3.4x10⁻⁷ = [H⁺] [B1-] / [B1]
Where B1- is the conjugate base of vitamin B1,
In equilibrium, the concentrations are:
[H⁺] = X
[B1-] = X
[B1] = 9.167x10⁻⁸M - X
Where X is reaction coordinate
Replacing:
3.4x10⁻⁷ = [X] [X] / [9.167x10⁻⁸M - X]
3.117x10⁻¹⁴ -3.4x10⁻⁷X = X²
3.117x10⁻¹⁴ -3.4x10⁻⁷X - X² = 0
Solving for X:
X = -4.15x10⁻⁷M. False solution. There is no negative concentrations.
X = 7.51x10⁻⁸MThat means from the equilibrium of vitamin B1, the [H⁺] = 7.51x10⁻⁸M
From the autoinoization of water:
[H⁺] = 1.0x10⁻⁷M
[H⁺] in the solution is:
1.0x10⁻⁷M + 7.51x10⁻⁸M = 1.751x10⁻⁸M
As pH = -log[H⁺]
pH = 6.76What are the correct products for the following reaction? ---->
K2SO4 + MgF2 ---->
Question 3 options:
2KF + MgSO4
F2SO4 + K2Mg
No reaction will occur
K2SO4 + F2Mg
Answer:
2KF+MgSO4
Explanation:
The correct product of the reaction above is 2KF + MgSO4.
What is a chemical reaction?A chemical reaction is a reaction in which the reactants or reacting substances react or combine together to produce the products.
Therefore, The correct product of the reaction above is 2KF + MgSO4.
Learn more about chemical reactions below.
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Experiments were done on a certain pure substance X to determine some of its properties. There's a description of each experiment in the table below. In each case, decide whether the property measured was a chemical or physical property of X, if you can. If you don't have enough information to decide, choose can't decide in the third column.
Property P: A small sample of X is dissolved in water. Drops of another solution, containing dissolved sodium hydroxide, are slowly added, and a pH indicator is used to determine when the sodium hydroxide has completely reacted with X. From the amount of sodium hydroxide needed, the value of P may be calculated.
Property D: A sample of X is carefully weighed and put inside a vented flask. Water is added to the flask until it just covers the sample, and the volume of sample and water is recorded. Then the sample is removed and the volume of water alone recorded. From the mass of the sample and the difference in volumes, the value of R may be calculated.
Property V: Sample of X is melted and put into a reservoir from which a very thin tube leads down. The rate at which X flows out of the tube is measured, and from this rate the value of V may be calculated.
Answer:
The property P measured, was a chemical property of X; its acidity
The property D measured, was a physical property of X; its density
The property V measured, was a physical property of X; it's viscosity probably.
Explanation:
1. The property V that was measured is the acidity of X. The acidity of X is a measure of the concentration of hydrogen ions present in it. When drops of another solution, containing dissolved sodium hydroxide, are slowly added, and a pH indicator is used to determine when the sodium hydroxide has completely reacted with X, the procedure determines the concentration of X that would neutralize the base, sodium hydroxide.
2. The property of X determined in the step is the density of X, a physical property. First the volume of X was determined by the displacement method. Then the density of X is calculated from its mass and volume.
3. Since during the determination of the property V, there was no alteration done to the chemical constitution of X, the property thus determined is a physical property. Melting of the sample is a physical change and likewise its flow rate through a very thin tube.
According to the Michaelis-Menten equation, when an enzyme is combined with a substrate of concentration s (in millimolars), the reaction rate (in micromolars/min) is
Answer:
The answer is "A"
Explanation:
Please find the complete question in the attachment file.
[tex]\to R(s)= \frac{As}{K+s}[/tex]
when the s in the approach, that is infinity R(s) tends
[tex]\to \frac{A}{\frac{K}{s}+1} \\\\ \to\frac{A}{0+1} \\\\ \to\frac{A}{1} \\\\ \to A[/tex]
Is caffeine additive?
Explain
Answer:yes anything can be addictive
Explanation:
Answer:
While caffeine produces a small rise in dopamine, it does not cause the large surge that unbalances the reward circuits in the brain and is necessary for an addiction. So even though the word “addiction” is often used casually, caffeine is not addictive (scientifically speaking).
Suppose that you are given a mixture of proteins with their properties provided in the following chart.
Isoelectric point PI Molecular weight
Protein A 4.1 80
Protein B 9.0 81
Protein C 8.8 37
Protein D 3.9 172
Choose one combination of techniques that can be used to isolate Protein B from Proteins A, C, and D.
a. gel filtration chromatography and ultracentrifugation
b. dialysis and ultracentrifugation
c. dialysis and ion exchange chromatography
d. ion exchange chromatography and gel filtration chromatography
Answer:
The correct option is d. ion exchange chromatography and gel filtration chromatography
Explanation:
The mixture contains proteins with different isoelectric points and molecular weights. Ion exchange chromatography separates the proteins with different electric charges, which depend on the isoelectric point. At certain pH of the aqueous medium, the proteins will have a certain electric charge and they will be retained differently in the stationary phase. Proteins A and D have similar isoelectric points (around 4.0) and maybe they cannot be efficiently separated by this method; the same occurs with protein B and C (with an isoelectric point around 9.0). To separate proteins A from D and protein B from C, it could be used gel filtration chromatography. This separation method is based on differences in molecular weights. So, at the end of the process, we will obtain the proteins A, B, C, D separated one from each other.
calculate the number of atoms in 0.25 mole of uranium.
Answer: 0.25 mol × (6.02214 × 1023 /mol) = 1.5 × 10
Explanation: Hope that helps
An atom has 81 electrons, 84 neutrons, and 82 protons. What element is this atom?
Answer:
Lead
Explanation:
The subatomic particles within an atom can be used to know the atom or element given.
Of particular interest is the number of protons within the atom.
The periodic table is based on the atomic number of atoms. This atomic number is the number of protons within an atomic space.
So; If we know the number of protons within an atom, we can know the element.
The number of protons given is 82, the element is therefore lead.
Answer:
The atomic number of polonium is 84. The atomic number lead is 82.
Explanation:
The gas carbon dioxide is a pure substance. Which of the following is true about carbon dioxide? (5 points)
Select one:
a. Carbon and oxygen are chemically bonded in it.
b. Carbon and oxygen retain their original identity in it.
c. It can be separated into carbon and oxygen using physical methods.
d. The proportion of carbon and oxygen is different in different samples of the gas.
Answer:
Carbon and oxygen are chemically bonded in it.
Explanation:
The other answer choices do not apply for compounds, but rather for mixtures instead.
Answer the given question: use Chapter 1 of notebook
How many formula units are there in 3.20x 102 moles of LICI? (2pts.)
Conversion factor: 1 mole LICI=
_formula of LICI
Students, draw anywhere on this slide!
Answer:
1.93 x 10²⁶ formula units
Explanation:
Given parameters:
Number of moles of LiCl = 3.2 x 10² moles = 320moles
Unknown:
Number of formula units in this compound = ?
Solution:
The mole is used a reference to determine the number of substances matters contain.
A mole contains the Avogadro's number of particles.
So;
1 mole of a substance contains 6.02 x 10²³ formula units;
320 moles of LiCl will contain 320 x 6.02 x 10²³ = 1.93 x 10²⁶ formula units
PLZ HELP ASAP WILL GIVE BRAINLIST
2AlCl3 + 2Al + 3Cl2
If 20.0 g of aluminum chloride are decomposed, how many molecules of chlorine gas are produced?
A )6.63 x 1022 molecules CI
B )2.70 x 1023 molecules Cl2
C )1.35 x 1023 molecules Cl2
D )9.42 x 1023 molecules Cl2
Explanation:
Molar mass of AlCl3 = 133.34g/mol
Moles of AlCl3 used
= 20.0g / (133.34g/mol) = 0.150mol
Mole Ratio of AlCl3 to Cl2 = 2 : 3,
Moles of Cl2 produced
= 0.150mol * (3/2) = 0.225mol
We know that 1 mole of any gas has
6.023 * 10²³ molecules.
Hence, number of molecules in Cl2
= 0.225mol * (6.023 * 10²³/mol)
= 1.35 * 10²³ molecules. (C)
How many moles of water can be formed from 0.57 moles of hydrogen gas?
Answer:
0.57 water
Explanation:
To solve this problem, we need to write the reaction expression first.
The reactants are oxygen gas and hydrogen gas.
They react to give a product of water
2H₂ + O₂ → 2 H₂O
Given that;
Number of moles of hydrogen gas = 0.57moles
From the balanced reaction expression;
2 moles of hydrogen gas produces 2 moles of water
So;
0.57mole of hydrogen gas will also produce 0.57 water
chemistry
Definition in your own words. I will check if you got it from online.
Word:
Oxidizer
Answer:
oxidizer: one used to support the combustion of a rocket propellant
word: a single distinct meaningful element of speech or writing
Explanation:
In Part III, the methyl orange indicator is used to monitor the equilibrium shifts of the acetic acid/acetate ion system. The methyl orange equilibrium established with water is Hmo(aq)(orange-red) H2O(l) H3O (aq) mo-(aq)(yellow). You compared the color of the solutions in three test tubes that initially contained 3 mL of 0.1 M acetic acid and a few drops of methyl orange indicator. In the first test tube, you added 1.0 M NaC2H3O2 drop wise. What color change was observed and what did this color change indicate about the shift in the methyl orange equilibrium
Answer:
See explanation
Explanation:
Let us look at the situation closely, the undissociated Hmo is red in colour while the mo^- is yellow in colour.
This means that an acidic solution will appear red while a basic solution will appear yellow in colour.
NaC2H3O2 is a basic salt. When it is introduced, the acetate ion pulls a proton from water forming CH3COOH. CH3COOH is a weak acid and largely does not dissociate, it means that the undissociated acid remains in the solution leaving only the OH^- ions floating around thereby making the solution basic.
The colour of the system now changes to yellow.
Consider the equilibrium;
CH3COO^-(aq) + H2O(l) ------> CH3COOH(aq) + OH^-
Addition of NaC2H3O2 causes the equilibrium of this system to shift to the right.
The methyl orange water equilibrium also shifts towards the position where more mo^-(yellow) is produced.
15.0 g of Fe and 25.0 g of sand are added to 250.0 g of water. a. Determine the percent mass of Fe, sand, and water in the mixture. b. Create a flow chart illustrating how you could separate each of the mixture’s components. c. Explain which step of the separation is likely to have the highest amount of error.
Answer:
A. percentage mass of iron = 5.17%
percentage mass of sand = 8.62%
percentage mass of water = 86.205%
B. (Iron + sand + water) -------> ( iron + sand) ------> sand
C. The step of separation of iron and sand
Explanation:
A. Percentage mass of the mixtures:
Total mass of mixture = (15.0 + 25.0 + 250.0) g =290.0 g
percentage mass of iron = 15/290 * 100% = 5.17%
percentage mass of sand = 25/290 * 100% = 8.62%
percentage mass of water = 250/290 * 100% = 86.205%
B. Flow chart of separation procedure
(Iron + sand + water) -------> separation by filtration using filter paper and funnel to remove water --------> ( iron + sand) -----------> separation using magnet to remove iron ------> sand
C. The step of separation of iron and sand by magnetization of iron will have the highest amount of error because during the process, some iron particles may not readily be attracted to the magnet as they may have become interlaced in-between sand grains. Also, some sand particle may also be attracted to the magnet as they are are borne on iron particles.
How did fossil records support the existence of a supercontinent?
Similar fossils provided evidence that a meteor hit Earth.
Similar fossils were found in different continents.
Fossil records showed how old the continents were.
Fossil records provided evidence that dinosaurs existed.
Answer:
B. Similar fossils were found in different continents.
Answer:
B. Similar fossils were found in different continents.
Explanation:
3. What determines the frequency (color) of photons?
What is the iupac name of ch3ch(oh)so3na
Answer:
propane-1-ol.
is the ans.
ok
is the name
ok
How do I know I'm a fish eh sorry
2. Each cart below is pushed across a room with the same amount of force. Which cart will result in the greatest change in speed?
A )A 15 kg cart being pushed with a 200 N force
B ) A25 kg box being pushed with a 200 N force
C )A 45 kg cart being pushed with a 200 N force
D )A 35 kg box being pushed with a 200 N force
Answer: A 15 kg cart being pushed with a 200 N force.
Explanation:
The 15 kg cart is the lightest, so it has the least amount of friction on the ground.
The cart that will result in the greatest change in speed is the cart with a mass of 15 Kg
The correct answer to the question is Option (A) A 15 kg cart being pushed with a 200 N force
Acceleration is defined as the change in velocity of an object with time.
Acceleration is also related to force and mass according to the following equation:
Acceleration (a) = Force (F) / mass (m)
a = F / m
To answer the question given above, we shall determine the acceleration of the cart in each option.For Option A:
Mass (m) = 15 Kg
Force (F) = 200 N
Acceleration (a) =?a = F / m
a = 200 / 15
a = 13.33 m/s²For Option B:
Mass (m) = 25 Kg
Force (F) = 200 N
Acceleration (a) =?a = F / m
a = 200 / 25
a = 8 m/s²For Option C:
Mass (m) = 45 Kg
Force (F) = 200 N
Acceleration (a) =?
a = F / m
a = 200 / 45
a = 4.44 m/s²For Option D:
Mass (m) = 35 Kg
Force (F) = 200 N
Acceleration (a) =?a = F / m
a = 200 / 35
a = 5.51 m/s²From the illustrations made above, we can see that the cart with a mass of 15 Kg has the greatest acceleration (i.e change in speed)
Therefore, the correct answer to the question is Option (A) A 15 kg cart being pushed with a 200 N force
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water is a unique material in that the density of the solid is lower than the density of the liquid (which is why ice forms at the top of a pond and why ice floats in our drinks). if the density for ice at 0C is .917g/mL and the density for water at 0C is .999 g/mL, what is the calculated free space (as %) for each of these materials. you will need to estimate the volume of water as the sum of 2 H atoms and 1 O atom with radii 37 and 66 pm respectively. note that you will also have to assume a quantity of water to perform this exercise
Answer:
% Free space in water = [tex]\frac{9.945* 10^{-7} }{1*10^{-6} }[/tex]×100 = 99.45%
% Free space in ice = [tex]\frac{9.98* 10^{-7} }{1*10^{-6} }[/tex]×100 = 99.8%
Explanation:
As given ,
Density for ice at 0⁰C = 0.917 g/ml
Density for water at 0⁰C = 0.999 g/ml
Radii of H atoms = 37 pm
Radii of O atoms = 66 pm
Now,
Consider 1 ml of water = 1 cm²
As , we know that mass of water in 1 cm² = 0.999 g
Moles of water = [tex]\frac{0.999}{18} = 0.056[/tex]
Volume of H₂O = 1.624×[tex]10^{-31}[/tex] m²
Now,
Volume occupied by water = 0.056×6.022×[tex]10^{23}[/tex]× 1.624×[tex]10^{-31}[/tex] m²
= 5.48×[tex]10^{-9}[/tex] m²
⇒Volume occupied by water = 5.48×[tex]10^{-9}[/tex] m²
Now,
Free space = 1×[tex]10^{-6}[/tex] - 5.48×[tex]10^{-9}[/tex] = 9.95×[tex]10^{-7}[/tex] m²
% Free space = [tex]\frac{9.945* 10^{-7} }{1*10^{-6} }[/tex]×100 = 99.45%
Now,
Consider 1 ml of ice = 1 cm²
S.I unit of ice = 1×[tex]10^{-6}[/tex] m²
As , we know that mass of water in 1×[tex]10^{-6}[/tex] m² = 0.917 g
Moles of ice = [tex]\frac{0.917}{18} = 0.012[/tex]
Volume of H₂O = 6.022×[tex]10^{23}[/tex] ×0.012
Volume of ice unit = [tex]\frac{4}{3} \pi (37*10^{-12})^{3} *2 + \frac{4}{3} \pi (66*10^{-12})^{3} = 1.624*10^{-31}m^{3}[/tex]
Now,
Volume occupied by water = 0.012×6.022×[tex]10^{23}[/tex]× 1.624×[tex]10^{-31}[/tex] m²
= 1.17×[tex]10^{-9}[/tex] m²
⇒Volume occupied by water = 1.17×[tex]10^{-9}[/tex] m²
Now,
Free space = 1×[tex]10^{-6}[/tex] - 1.17×[tex]10^{-9}[/tex] = 9.98×[tex]10^{-7}[/tex] m²
% Free space = [tex]\frac{9.98* 10^{-7} }{1*10^{-6} }[/tex]×100 = 99.8%
1. How many molecular orbitals can be built from the valence shell orbitals in O2?
Answer:
Atomic oxygen has 6 valence electrons and 4 valence orbitals (2s, 2px, 2py, and 2pz). We can draw a Lewis structure of molecular oxygen with a double bond between the oxygen atoms and 2 non-bonding pairs of electrons on each atom.
Energy from the Sun reaches Earth through
Convection
O radiation
conduction
all the above
Solar Radiation(Basically Radiation)
What is aspartame? EXPLAIN
Answer:
it's an artificial non-saccharide sweetener 200 times sweeter than sucrose, and is commonly used as a sugar substitute in foods and beverages. it's a methyl ester of the aspartic acid/phenylalanine dipeptide with the trade names NutraSweet, Equal, and Canderel
Explanation:
Answer:
Aspartame is some type of very sweet substance that is used as an artificial sweetener, and chiefly in low-calorie products. It is a derivative of aspartic acid and phenylalanine.
Explanation:
differences between selenium tellurium and polonium
Explanation:
Selenium and tellurium are rare elements, respectively, in order of crustal abundance. However, polonium, on account of its radioactive decay, is less abundant. The main source of selenium and tellurium is the anode slime deposited during the electrolytic refining of copper.
Question 6 / 20
Which statement is always true about conservation of matter?
A. The mass of a system does not change during a chemical reaction
B. If a solid forms, the mass of a system increases
C. If a gas forms, the mass of a system decreases
D. The mass of a system changes when a substance changes from liquid to gas, but it does not change in
a chemical reaction
Select an answer
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Answer:
i gussss D is the answer may be
Answer:
A. The mass of a system does not change during a chemical reaction
Explanation:
Correct Answer
GRADE 5 SCIENCE MYA-2020-2021
Testosters are testing the choict of light on a radiometer Team 1 finds that blue light makes the radiometer spin slower when a blue light is 35 centimeters (cm) away. To validate Team 1's test results, how must
Text with and that is 20 cm away
Test what that is 45 cm away
Test with a green light that is 40 cm away
Test with the light that is 35 cm away
Answer:
Test it with a blue light that is 45 cm away.
Explanation:
how many moles are there in 67.2 grams of h2
Answer: 33.3 moles
Explanation: 67.2 g H2 = 67.2/2.016 = 33.3 moles