Answer:
Average atomic mass of thallium = 204.4 amu.
Explanation:
Given data:
Abundance of thallium-203 = 30%
Abundance of thallium-205 = 70%
Average atomic mass = ?
Solution:
Average atomic mass of thallium = (abundance of 1st isotope × its atomic mass) +(abundance of 2nd isotope × its atomic mass) / 100
Average atomic mass of thallium = (30%×203)+(70%×205) /100
Average atomic mass of thallium = 6090 + 14350 / 100
Average atomic mass of thallium = 20440 / 100
Average atomic mass of thallium = 204.4 amu.
20 POINTS A group of students is conducting a density experiment with two blocks. Block 1 has more mass and less volume than Block 2. Based on this information, the student can correctly conclude that *
both blocks have densities less than water's density
both blocks have densities greater than water's density
Block 1 has a higher density than Block 2
Block 1 has a lower density than Block 2
Answer:
Block 1 has a higher density then block 2
Explanation:
Answer:
Yep, the correct answer is C. Block 1 has a higher density than block 2.
Explanation:
Which would most likely be the pH of a highly-corrosive acid? 1 5 8 11
Answer:
it is 1 because of it is below 7 then it will be dangerous for humans
The pH of the highly corrosive acid, given the data from the question is 1
What is pH ?This is simply a measure of the acidity / alkalinity of a solution.
The pH measures the hydrogen ion concentration while the pOH measures the hydroxide ion concentration
pH scaleThe pH scale is a scale that gives an understanding of the variation of the acidity / alkalinity of a solution.
The scale ranges from 0 to 14 indicating:
0 to 6 indicates acid 7 indicates neutral 8 to 14 indicate basicNOTE: The lesser the pH of a substance, the more acidic (corrosive) it is and the greater the pH of the substance, the less acidic (corrosive) it is.
With the above information about pH, we can conclude that the pH of the highly corrosive acid, given the data is 1
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1) The speed constant was determined for the first order decomposition of an organic compound at various temperatures:
Calculate the activation energy for the reaction. Build a graph of Arhenius
2) The hydrolysis of sucrose. in which a sucrose molecule is broken in a glucose molecule and a fructose molecule, is part of the digestive process. Calculate the speed constant for the hydrolysis of sucrose at 35,0 C knowing that k=1,0x10^-3 L mol^-1s^-1 at 37 C and that the activation energy is 108kj mol^-1
Answer:
1) Eₐ = 100.3 kJ/mol
2) k = 7.62×10⁻⁴ M⁻¹s⁻¹
Explanation:
1) Make an Arrhenius graph by plotting ln(k) on the y-axis and 1/T on the x-axis (don't forget to convert temperature to Kelvin).
The slope of the line is equal to -Eₐ/R.
-Eₐ/R = -12065
Eₐ = 100,300 J/mol
Eₐ = 100.3 kJ/mol
2) Since we know the slope of ln(k) vs 1/T is -Eₐ/R, we can say:
-Eₐ/R = (ln(k₂) − ln(k₁)) / (1/T₂ − 1/T₁)
Plug in values and solve for k:
-(108,000 J/mol) / (8.314 J/mol/K) = [ln(k) − ln(1.0×10⁻³)] / [1/(35+273.15 K) − 1/(37+273.15 K)]
-12990 = [ln(k) + 6.91] / (2.09×10⁻⁵ K⁻¹)
-0.272 = ln(k) + 6.91
ln(k) = -7.18
k = 7.62×10⁻⁴ M⁻¹s⁻¹
in addition to Earthquake, hurricane, which of the following could be categorized as a "disaster" risk?
Answer:
I think its a World War.
Explanation:
This is just what my sister told me, since the cost for the war could make a country poor and the damage it could cause could lead a country to disaster.
i think d answer is tsunami
can someone help me im doing chemistry right now and I have a question which I have no idea how to solve and I need to show work it it needs to be shown in scientific notation
(7.6x10^-1)+(2.0x10^-2)
Why is H2S called an analytical agent?
Answer:
Hydrogen sulfide is an newly recognized signical molecule with very potent cytoprotective actions.
Consider the reaction when aqueous solutions of calcium nitrate and potassium carbonate are combined. The net ionic equation for this reaction is:
Answer:
Ca2+(aq) + 2OH-(aq) → Ca(OH) 2 ( s )
Explanation:
The balanced equation is given as;
Ca(NO 3 ) 2 ( aq ) + 2KOH(aq) → Ca(OH) 2 ( s ) + 2KNO 3 ( aq )
The net ionic equation features only ions that actually participated in the reaction. These ions are identified due to their change in oxidation numbers. Also, the aqueous compounds are broken down into ions.
Ca2+ + 2NO3- + 2K+ + 2OH- → Ca(OH) 2 ( s ) + 2K+ + 2NO3-
Ions present in both sides of the equation above. These are; NO3-, K+ and OH-
The net ionic equation is;
Ca2+(aq) + 2OH-(aq) → Ca(OH) 2 ( s )
Scientists utilize models for a variety of different purposes, but each type of scientific model has limitations. What might
be a limitation of existing solar system models?
a. They are not based on experimentation.
b. They are used for prediction.
C. They cannot be changed.
d. They are based on current knowledge,
Please select the best answer from the choices provided
А
B
С
D
Answer:
D.They are based on current knowledge.
Explanation:
Guy above me is wrong
The chemical formula for calcium chloride is
Answer: anhydrous CaCl 2 :0H 2 O
monohydrate CaCl 2 :1H 2 O
a di-hydrate CaCl 2 :2H 2 O
Explanation:
How many protons and electrons does a hydrogen atom have?
A hydrogen atom contains 1 electron, 1 proton
Explanation:
A sample of a metal has a mass of 23.4 g and a volume of 3.0 mL. What is the sample’s most likely identity?
A. Aluminum (2.8 g/mL)
B. Iron (7.8 g/mL)
C. Copper (8.9 g/mL)
D. Gold (19.3 g/mL)
Answer:
B. Iron (7.8 g/mL)
Explanation:
23.4/3 = 7.8
7.8g/mL
The identity of a sample of a metal that has a mass of 23.4 g and a volume of 3.0 mL is iron with a density of 7.8g/mL.
How to calculate density?The density of a substance can be calculated by dividing the mass of the substance by its volume. That is;
Density = mass (g) ÷ volume (mL)
According to this question, a sample of a metal has a mass of 23.4 g and a volume of 3.0 mL. The density of the metal is as follows:
Density = 23.4g ÷ 3mL
Density = 7.8g/mL
Therefore, the identity of a sample of a metal that has a mass of 23.4 g and a volume of 3.0 mL is iron with a density of 7.8g/mL.
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A chemist working as a safety inspector finds an unmarked bottle in a lab cabinet. A note on the door of the cabinet says the cabinet is used to store bottles of pentane, tetrahydrofuran, carbon tetrachloride, methyl acetate, and ethanolamine. The chemist plans to try to identify the unknown liquid by measuring the density and comparing to known densities. First, from his collection of Material Safety Data Sheets (MSDS), the chemist finds the following information: liquid density pentane tetrahydrofuran carbon tetrachloride methyl acetate ethanolamine Next, the chemist measures the volume of the unknown liquid as and the mass of the unknown liquid as . Calculate the density of the liquid. Round your answer to significant digits. Given the data above, is it possible to identify the liquid
Answer:
The liquid can be identified
Explanation:
Given that density is defined as mass per unit volume.
We have the following information regarding the unknown liquid;
Mass= 1.40 kg = 1400 g
Volume = 1378 cm^3 = 1378 ml
Density of unknown liquid = 1400/1378 = 1.012 g/ml this is approximately 1.0 g/ml
It is possible to identify the liquid, the liquid is ethanolamine
A sample of an ideal gas has a volume of 2.38 L at 283 K and 1.03 atm. Calculate the pressure when the volume is 1.97 L and the temperature is 307 K.
Gas Has A Volume Of 2.21 L At 287 K And 1.11 Atm. Calculate The Pressure When The Volume Is 1.03 L And The Temperature
Explanation:
Photons are emitted as electrons in the atom jump up in energy. true or false?
Answer:
true
Explanation:
photons are emitted when electrons move from from a lower energy level to a higher energy level
Calculate the density of an
object with a mass of 58g and a
volume of 20 mL.
Enter
Answer:
D = 2.9 g/mL
Explanation:
Density = Mass over Volume
D = m/V
Step 1: Define
m = 58 g
V = 20 mL
D = unknown
Step 2: Substitute and Evaluate for Density
D = 58 g/20 mL
D = 2.9 g/mL
Fill in the blank... spelling counts.
Speed is the ______ something travels divided by the _____ It takes to travel that dinstance.
Answer:
[tex]speed = \frac{distance}{time}[/tex]
Which sample matter is a pure substance
Answer:
Explanation:
If you have options, could you please tell me so I can further help you. If you just need an example then
Examples of pure substances include iron, steel, and water
Hope this helps (:
Answer
These are the following answers
A) zinc oxide
B) sugar dissolved in water
C) pond water
D) soil
Explanation:
What is the correct order of star colors from hottest to coolest?
white, yellow, red, blue
yellow, orange, white, red
red, orange, yellow, blue-white
blue, white, yellow-white, orange
Answer: The answer is blue, white, yellow-white, orange.
Explanation: These are the two basic reasons for different star colors:
Temperature – cooler stars are red, warmer ones are orange through yellow and white. The hottest stars shine with blue light
Age – As a star ages it produces different chemicals which burn at different temperatures. We can use a star’s color to show its relative age
Answer:
OR D
Explanation:
D on edge 2020
1. As an electron in an atom moves from a higher energy state to a lower energy state, the atom
(A) becomes a negative ion
(C) releases energy
(B) becomes a positive ion
(D) absorbs energy
Answer:
(C) releases energy
Explanation:
From Bohr's model of the atom, we can understand the energy transitions involved when an electron moves from one energy level to another.
An electron in an energy level has a definite amount of energy associated with it at that level. When electrons change state, they must absorb or emit the exact amount of energy which will bring them from initial to final states. When the electron is excited, it moves from the ground state to an excited state, it must must absorb energy. On returning from an excited state, energy is emitted.(C) releases energy
From Bohr's model of the atom:
We can understand the energy transitions involved when an electron moves from one energy level to another.
An electron in an energy level has a definite amount of energy associated with it at that level. When electrons change state, they must absorb or emit the exact amount of energy which will bring them from initial to final states. When the electron is excited, it moves from the ground state to an excited state, it must must absorb energy. On returning from an excited state, energy is released or emitted.Therefore, option C is correct.
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What molar concentration of hydrochloric acid (HCl) is needed to prepare a disinfectant solution with a pH
Answer:
The correct approach is "3.1×10⁻³ M".
Explanation:
As we know,
[tex]pH=-log[H_{3}O^+][/tex]
[tex]pH=2.5[/tex]
[tex][H_{3}O]^+= \ ?[/tex]
Now,
⇒ [tex]-log[H_{3}O]^+=2.5[/tex]
⇒ [tex][H_{3}O]^+=10^{-2.5}[/tex]
⇒ [tex]=3.1\times 10^{-3} \ M[/tex]
So that the needed molar concentration of HCL will be:
= [tex]3.1\times 10^{-3} \ M[/tex]
The vaporization of Br2 from the liquid to the gas state requires 7.4 kcal/mol. write a reaction showing heat as a product or reactant
Answer:
Br₂(l) + ΔV → Br₂(g)
Explanation:
When a chemical or phase change occurs during a chemical process some heat is absorbed or released. For the process of vaporization of a substance, the heat (Usually required) is ΔV (How many energy is required for the process occurs).
In the vaporization of Br2 there are required 7.4kcal/mol, Δv. The reaction is:
Br₂(l) + ΔV → Br₂(g)What is the total pressure of a container in kpa if the partial pressures are 1.25 atm and 66.7 psi?
Answer:
586 kpa(kilopascal/1000 pascals)
Explanation:
given 1.24 atm(standard atmosphere), and 66.7 psi(pound force per square inch).
To find the total pressure we should use dalton's law of partial pressures which is the sum of the pressures of each individual gas.
then we convert them to pascals and divide by 1000 to get the measurement in kilopascal.
knowing that 1 atmosphere is proportional to around 14.696 psi. We can multiply our given measure of atm by that and sum it by psi like so. 1.24×14.6959 = 18.22298.
Then,
18.22298+ 66.7 = 84.92298
psi.
Since 1 psi is proportional to around 6894.76 pascals. 1 psi will be 68.9476 kilopascal. 84.92298 * 6.89476 = 585.523336 ≈ 586
Which element is a gas?
A.Br
B.C
C.B
D.Be
Answer:
A.Br
Explanation:
Bromine is the only gas from the choices provided. It belongs to the group of halogens, group 7.
It has atomic number of 35 and it belongs to the p-block on the periodic table.
C is carbon and carbon is a solid matter B is boron and boron is a metalloid Be is beryllium and silvery white metalOnly Bromine is the gas from the given choices. It is fuming liquid and when exposed, it becomes gaseous.
100 POINTS!!!!
The passage states that water exists in three states on Earth. Trace the changes in state of matter, from snow-capped mountain, through the water cycle, and finally back to the snow-capped mountain.
A) melting snow; lliquid runoff; liquid water evaporates; water freezes; precipitation of frozen water (snow) back to Earth
B) solid snow melts; liquid water flows to oceans; water evaporates; water condenses to form clouds; snow falls back to Earth
C) solid snow melts; liquid water evaporates; gaseous water vapor condenses; water freezes; precipitation of frozen water (snow) back to Earth
D) solid snow melts; liquid water soaks into ground; plants take up water; water evaporates; water freezes; precipitation of frozen water (snow) back to Earth
YOU CAN HAVE ALL MY POINTS AND THE BRAINLIEST PLS HELP ME!!!!
Answer:
C
Explanation:
solid snow melts; liquid water evaporates; gaseous water vapor condenses; water freezes; precipitation of frozen water (snow) back to Earth
only cycle that makes sense
Answer:
The answer is C
Explanation:
A deck of cards has dimensions 8.9cm x 5.72cm x 1.82 cm. What is the volume of the deck in cubic centimeters?
Answer:
92.65256 cm^3
Explanation:
To find this, we can simply multiply all three dimensions to get the answer in cubic centimeters, and we get the answer above. If you want to be more specific, we can go by the sigfig rule and the answer would be rounded to 93 cm^3.
An antacid tablet contains 640.0 mg of magnesium oxide per tablet.
What volume of 0.1000 M stomach acid (HCI) could one tablet neutralize?
Answer:
317.6 mL
Explanation:
Step 1: Write the balanced neutralization equation
MgO + 2 HCl ⇒ MgCl₂ + H₂O
Step 2: Calculate the mass corresponding to 640.0 mg of MgO
The molar mass of MgO is 40.30 g/mol. The moles corresponding to 640.0 mg (0.6400 g) of MgO are:
0.6400 g × (1 mol/40.30 g) = 0.01588 mol
Step 3: Calculate the moles of HCl that react with 0.01588 moles of MgO
The molar ratio of MgO to HCl is 1:2. The moles of HCl are 2/1 × 0.01588 mol = 0.03176 mol
Step 4: Calculate the volume of 0.1000 M HCl that contains 0.03176 moles
0.03176 mol × (1 L/0.1000 mol) = 0.3176 L = 317.6 mL
A hawk swoops down and catches a squirrel. The squirrel provides energy for the hawk. What happens to the rest of the matter?
Answer:
The rest of the food molecule is converted to other carbon molecules. The hawk cannot consume all the parts of the squirrel. It will feed as a carnivore on the fleshy part of its prey. The matter is converted to other carbon molecules
Explanation:
Order: Vitamin K (Aquamephyton) 1 mg IM x 1 dose Newborn: Weight 4 kg Supply: 10mg/mL vial How many mLs would be given
Answer:
Volume(ml) of drug required = 0.1 ml
So, medicine is safe for this child.
Explanation:
Given:
Desired dose (D)= 1 mg
Dose in hand (H) = 10 mg
Quantity (Q) = 1 ml
Computation:
Volume(ml) of drug = [Desired medicine / medicine in hand] Quantity.
Volume(ml) of drug required = [1/10]1
Volume(ml) of drug required = 0.1 ml
So, medicine is safe for this child.
Question 1 of 10 What is molarity a measurement of? O A. The volume of liquid containing a dissolved substance B. The grams of a substance dissolved in a liquid O c. The concentration of a substance dissolved in a liquid O D. The number of moles of a dissolved substance
To do this measure called molarity is commonly used. Molarity (M) is defined as the number of moles of solute (n) divided by the volume (V) of the solution in liters. It is important to note that the molarity is defined as moles of solute per liter of solution, not moles of solute per liter of solvent.
so the answer is D.
hope this helps have a great day....!
According to the concept of molar concentration, molarity is defined as the number of moles of a dissolved substance.
What is molar concentration?Molar concentration is defined as a measure by which concentration of chemical substances present in a solution are determined. It is defined in particular reference to solute concentration in a solution . Most commonly used unit for molar concentration is moles/liter.
The molar concentration depends on change in volume of the solution which is mainly due to thermal expansion. Molar concentration is calculated by the formula, molar concentration=mass/ molar mass ×1/volume of solution in liters.
In terms of moles, it's formula is given as molar concentration= number of moles /volume of solution in liters.
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In Natural selection, individuals whose unique characteristics are well-suited for an environment tend to survive and produce more offspring. true or false? i need this help!right now!
Answer:
True
Explanation:
True. If an animal has attributes to it that help it survive better in an environment, it will survive better than its counterparts who do not have this attribute. More survival = More offspring
Answer:
True.
Explanation:
It's called survival of the fittest. Animals are genetically supposed to be well suited to their environment and if they aren't, they die out.