Answer:
Yes
Explanation:
It was Dmitri Mendeleev, a Russian chemist and teacher.
Answer:
No, it wasn't. On Feb.17 in 1869, a very intelligent Russian professor of chemistry, Dimitri Ivanovich Mendeleev created his first part of the periodic table. I hope that helps you.
Explanation:
Ernest Rutherford and Henry
Moseley used this subatomic
particle to differentiate atoms by
their atomic number.
Answer:
electron
Explanation:
How many electrons are located in the outermost orbit in the Bohr model of a boron atom?
A. 1
B. 2
C. 3
D. 4
According to the electronic configuration of boron, there are three electrons in the Bohr model of a boron atom.
What is electronic configuration?Electronic configuration is defined as the distribution of electrons which are present in an atom or molecule in atomic or molecular orbitals.It describes how each electron moves independently in an orbital.
Knowledge of electronic configuration is necessary for understanding the structure of periodic table.It helps in understanding the chemical properties of elements.
Elements undergo chemical reactions in order to achieve stability. Main group elements obey the octet rule in their electronic configuration while the transition elements follow the 18 electron rule. Noble elements have valence shell complete in ground state and hence are said to be stable.
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hydrogen peroxide slowly decomposes into water and oxygen.the enthalpy change of reaction can be calculated using standard enthalpies of formation.Using a Hess cycle what is the enthalpy change of reaction for this decomposition
Some dog foods contains corn and wheat that provide the dog with carbohydrates. Which claim explains why carbohydrates are important to cell processes?
A) They are a source of energy.
B) They make amino acids.
C) They form cell membranes.
D) They help chemical processes happen.
(Science 7th grade)
Hello!
The answer is that they are a source of energy!
Hope this helps!
the valency of nitrogen is 3 . Give reason
Answer:
The nitrogen atom has 5 electrons in the outermost shell, so it can accept 3 electrons to fulfil the octet structure. Therefore the valency of nitrogen is 3.
Ammonium cyanate (NH4CNO) reacts to form urea (NH2CONH2). at 65 degrees celsius, the rate constant, K is 3.60 L mol^-1 s^-1. what is the rate law for this reaction
Answer:
v = 3.60Lmol⁻¹s⁻¹ [NH₄CNO]²
Explanation:
The reaction at 65°C of ammonium cyanate to produce urea is:
NH₄CNO → NH₂CONH₂
The general rate law is:
v = K [NH₄CNO]ˣ
Where v is rate of the reaction, K is rate constant and x represents the order of reaction
Based on the units of the rate constant (Lmol⁻¹s⁻¹ = M⁻¹s⁻¹) the reaction must be order 2 and the rate law:
v = K [NH₄CNO]²
v = 3.60Lmol⁻¹s⁻¹ [NH₄CNO]²
. What is the density of a block of plastic if the volume of the block is 5 cm and the mass is 17.2 g?
Answer:
The answer is 3.44 g/cm³Explanation:
The density of a substance can be found by using the formula
[tex]density = \frac{mass}{volume} \\[/tex]
From the question
mass = 17.2 g
volume = 5 cm³
We have
[tex]density = \frac{17.2}{5} \\ [/tex]
We have the final answer as
3.44 g/cm³Hope this helps you
(A) Hemoglobin is 50% saturated (P50) at 20 torr, which is approximately equal to the partial pressure of O2 in muscle. The partial pressure of O2 in the lungs is 100 torr. If the Hill coefficient nh = 3, calculate how efficient hemoglobin is at O2 delivery. Express your answer as the difference between factional O2 binding in the lungs and fractional O2 binding in muscle (qlungs – qmuscle). (B) How would the efficiency of O2 delivery change if hemoglobin were not cooperative (i.e. if nh =1)?
Answer:
Explanation:
Given that:
P₅₀ = 20 torr in muscle
The partial pressure of O2 in lungs Po₂ = 100 torr
The hill coefficient [tex]n_h[/tex] = 3
According to the Hill coefficient;
[tex]\dfrac{\Upsilon}{1-\Upsilon}= (\dfrac{PO_2}{P_{50}})^n[/tex]
here;
[tex]\Upsilon[/tex] = fraction of haemoglobin monomers
[tex]\dfrac{\Upsilon}{1-\Upsilon}= (\dfrac{100}{20})^3[/tex]
[tex]\dfrac{\Upsilon}{1-\Upsilon}[/tex] = 125 θ lungs
However for θ muscle :
[tex](\dfrac{PO_2}{P_{50}})^n=( \dfrac{20}{20})^3[/tex]
= 125 (θ lungs) - 1 (θ muscle)
= 124
B.
if nh =1
[tex]\mathtt {\theta \ lungs} = \dfrac{\Upsilon}{1-\Upsilon}= (\dfrac{100}{20})^1[/tex]
[tex]\mathtt {\theta \ lungs} =5[/tex]
[tex]\mathtt {\theta \ muscle} = \dfrac{20}{20}^1[/tex]
(θ muscle) = 1
(θ lungs) - (θ muscle) = 5 - 1
(θ lungs) - (θ muscle) = 4
A) The efficiency of hemoglobin at O₂ delivery = 124
B) Efficiency of O₂ delivery will change by : 4
Given data:
Partial pressure of O₂ in lungs ( PO₂ ) = 100 torr
Partial pressure of O₂ in muscle = ( P₅₀ ) = 20 torr
Hill coefficient nh = 3
r = fraction of hemoglobin monomers
A) Determine the efficiency of hemoglobin at O₂ delivery
Given that Hill coefficient = [tex]\frac{r}{1-r} = (\frac{PO_{2} }{P_{50} } )^{n}[/tex]
= [tex]\frac{r}{1-r} = (\frac{100}{20})^{3}[/tex] = 125 ∅ Lungs
For Muscle :
[tex](\frac{20}{20} )^{3}[/tex] = 1 ∅ muscle
Therefore the efficiency of hemoglobin at 0₂ delivery
= ( ∅ lungs - ∅ muscle )
= ( 125 - 1 ) = 124
B ) Determine the change in efficiency of O2 delivery
when hill coefficient ( nh ) = 1
for lungs :
[tex]\frac{r}{1-r} = (\frac{100}{20})^{1}[/tex] = 5
for muscle :
[tex](\frac{20}{20} )^{1}[/tex] = 1
Therefore change on efficiency = ( 5 - 1 ) = 4
Hence we can conclude that The efficiency of hemoglobin at O₂ delivery = 124 and Efficiency of O₂ delivery will change by 4
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For the equation 2 HCI + Zn ⇒ H₂ +ZnCI₂ suppose you had 2.00 g HCI and enough Zn.
a. What mass, in grams, would you have of Zn?
b. How many grams of H₂ would be produced?
Please show your work!!
Answer:
Zinc weighs 65.38 grams per mole, so we’ve got 0.994 moles of zinc (I’ll worry about sig figs at the end). HCl weighs 36.46 grams per mile, so we’ve got 1.78 moles of HCl. However, two moles of HCl react with one mole of zinc. So only 1.78/2 = 0.890 moles of Zinc are going to react.
One mole of zinc produces one mole of hydrogen, which weigh 2.02 grams per mole. So 0.890 moles * 2.02 grams/mole means 1.90 grams of hydrogen will be produced.
Since we have 2 sig figs in the weights given, the answer should have 2 sig figs, thus 1.9 grams.
This is just an example
Four different methods are described for validating the results of a particular analysis. Indicate for each whether the method primarily checks the accuracy of the analysis or the precision of the analysis. Method 1: Five aliquots of the same sample are injected for a gas-chromatographic analysis by one person on the same day. a. precision.b. accuracy.Method 2: A known amount of analyte is added to an aliquot of the sample and analyzed with the sample. a. precision.b. accuracy. Method 3: Aliquots from a blood sample are sent to three separate laboratories for analysis using the same method. a. precision.b. accuracy. Method 4: Identical standards are analyzed by two different methods. a. accuracy.b. precision.
Answer:
Method 1 - precision
Method 2 - accuracy
Method 3 - precision
Method 4 - accuracy
Explanation:
The accuracy of a method refers to how close the experimental result is to the accepted value. Accuracy could be checked by carrying out the required test on the standard and not on the sample or by adding a known amount of analyte to the sample so that the results obtained can be carefully compared.
Precision on the other hand, refers to how close the results of a replicate analysis are to each other. In testing for precision, the analysis must be carried out several times, in order to check how close the results are to each other.
What atomic symbol completes this reaction?
ГРо
220
Po →
84
?
+
liei
O
224
Pb
82
04
2+
He
2
o
220
At
85
0 220
Rn
86
Answer:
Option C is correct = ₈₅At²²⁰
Explanation:
Given radioactive decay shows the beta emission.
²²⁰₈₄Po ₈₅At²²⁰ + ⁰₋₁e ⁻
Beta radiations are result from the beta decay in which electron is ejected. The neutron inside of the nucleus converted into the proton an thus emit the electron which is called β particle.
Properties of beta radiations:
1) They can travel in air in few meter distance.
2) These radiations can penetrate into the human skin.
3) The mass of beta particle is smaller than the alpha particles.
4) The sheet of aluminium is used to block the beta radiation
¹⁴₆C → ¹⁴₇N + ⁰₋₁e ⁻
The beta radiations are emitted in this reaction. The one electron is ejected and neutron is converted into proton.
the commands given in nucleus are throughout the cell by the
A.endoplamic reticulum
B.Flagella
C.mitochondria
D.golgi bodies
E.vacuole
Answer:
A.endoplamic reticulum
Explanation:
The endoplamic reticulum is an important organelle in protein synthesis. The nucleus contains DNA, which is the template for transcription of mRNA. mRNA acts as a message, which leaves the nucleus to become translated into proteins.
The endoplasmic reticulum is important in the synthesis, folding, and modification of proteins.
Help!!!
A. A halogen
B. An alkaline earth metal
C. An alkali metal
D. A transition element
Answer:
B?
Explanation:
geochemist measures the concentration of salt dissolved in Lake Parsons and finds a concentration of 3.89·gL−1. The geochemist also measures the concentration of salt in several nearby non-isolated lakes, and finds an average concentration of 2.1·gL−1. Assuming the salt concentration in Lake Parsons before it became isolated was equal to the average salt concentration in nearby non-isolated lakes, calculate the percentage of Lake Parsons which has evaporated since it became isolated. Be sure your answer has the correct number of significant digits.
Answer:
46%
Explanation:
When solving this problem we have to note that the amount of salt (in grams) before isolation and after isolation are equal. If [tex]V_1[/tex] represents its volume before isolation and [tex]V_2[/tex] its volume after isolation then:
[tex]2.1 \frac{g}{L} *V_1=3.89\frac{g}{L} *V_2\\\\\frac{V_2}{V_1} =\frac{2.1}{3.89}\\\\\frac{V_2}{V_1} =0.54\\\\This\ means\ after \ isolation\ the\ volume\ of water\ is\ 54\%\ of\ its\ original\ value.\\\\The\ amount\ of\ evaporation=1-\frac{V_2}{V_1} =1-0.54=0.46=46\%\\\\The\ amount\ of\ evaporation=46\%[/tex]
Concentration data is commonly monitored during a reaction to determine the order with respect to a reactant. Consider the types of observations listed, and determine which order is likely for that reactant. Assume all other factors are held constant.
An increase in the concentration of the reactant in solution causes the reaction rate to increase exponentially.
Choose...first order, second order, zero order
The reaction rate increases in direct proportion to the concentration of the reactant in solution.
Choose...first order, second order, zero order
The reaction rate is constant regardless of the amount of reactant in solution.
Choose...first order, second order, zero order
Answer:
An increase in the concentration of the reactant in solution causes the reaction rate to increase exponentially - first order
The reaction rate increases in direct proportion to the concentration of the reactant in solution -second order
The reaction rate is constant regardless of the amount of reactant in solution - zero order
Explanation:
The Order of Reaction refers to the power dependence of the rate on the concentration of each reactant. The order of reaction is determined experimentally and not necessarily by inspection.
Typically, in a second order reaction, the rate of reaction increases in proportion to increase in concentration.
For a first order reaction, the rate of reaction increases exponentially as the increase in concentration.
For a zero order reaction, the rate of reaction is independent of the concentration of the reactant.
How many km are in a foot
Answer:
0.000305 km
Explanation:
1 foot = 0.000305 kilometers
Answer:
[\tex]\huge\bold\red{brainiest answer}[/tex]1 km =3,280.8398950131foot
How can sediment be a bad thing??
Answer:
Sediment increases the cost of treating drinking water and can result in odor and taste problems. Sediment can clog fish gills, reducing resistence to disease, lowering growth rates, and affecting fish egg and larvae development.
Explanation:
Answer:
"Sediment increases the cost of treating drinking water and can result in odor and taste problems. Sediment can clog fish gills, reducing resistance to disease, lowering growth rates, and affecting fish egg and larvae development".
Explanation:
Which group is the most reactive?
*
Alkaline Earth Metals
Alkali metals
Noble Gases
Lanthanides
Answer:
alkali metals- Group 1
Explanation:
they have less valence electrons and therefore are more reactive
When warm air from a large body of water
Answer:
On a warm day, water absorbs from its warmer environment, lowering the air tempurature. On a cool night, heat is transferred from the water to its cooler environment, raising the air tempura
Explanation:
How much heat is required to raise the temperature of 93.5 gg of water from its melting point to its boiling point
Answer:
39270 J
Explanation:
The quantity of heat required to raise the temperature of a substance from its initial temperature to its final temperature is given by:
Q = mCΔT
m = mass of substance, C = specific heat capacity of substance, ΔT = temperature change = final temperature - initial temperature
Melting point = 0°C, boiling point = 100°C, m = 93.5 g = 0.0935 g, ΔT = boiling point - melting point = 100 - 0 = 100°C, C = 4200 J/kg°C
Q = mCΔT
Q = 0.0935 × 4200 × 100 = 39270 J
Calculate the volume of a 0.750 M solution containing 67.0 g of KNO3
(gives you 20 points!)
Answer:
Volume of solution is 0.88 L.
Explanation:
Given data:
Molarity of solution = 0.750 M
Mass of KNO₃ = 67.0 g
Volume of solution = ?
Solution:
Molarity is used to describe the concentration of solution. It tells how many moles are dissolve in per litter of solution.
Formula:
Molarity = number of moles of solute / L of solution
Now we will calculate the number of moles.
Number of moles = mass/molar mass
Number of moles = 67.0 g/ 101.1 g/mol
Number of moles = 0.66 mol
Now we will put the values in molarity formula.
0.750 M = 0.66 mol / L of solution
L of solution = 0.66 mol / 0.750 M
L of solution = 0.88 L
Volume of solution is 0.88 L.
I’m not good at chemistry
Answer:
λ = 5.56 × 10⁻³ m
Explanation:
You have to use the formula c = λv to solve the problem. Review what you are given. You are given v and c, where v = 5.40 × 10¹⁰ Hz and c = 3.00 × 10⁸ m/s. The value c is for the speed of light and is something you need to memorize. You will use it often in physics and sometimes in chemistry.
Now that you figured out what you know, you can see that there is only one unknown, allowing you to solve.
c = λv
λ = c/v
λ = (3.00 × 10⁸ m/s)/(5.40 × 10¹⁰ Hz)
λ = 5.56 × 10⁻³ m
It takes 15.0 seconds to run 100.0 meters if you run .0500 how many meters will you run
Answer:
150 seconds
Explanation:
How would you prepare 250.0ml of 0.5 M solution from 6 M stock solution of NaCl?
Answer:
I would place 0.5 M solution of the 6.0 stock solution to a 250 mL volumetric flask and then add 250 mL of water.
Explanation:
Select the correct responses to the questions from the drop-down menus.
Which type of precipitation freezes when it comes into contact with a cold surface?
Which type of precipitation is round pellets of ice more than 5 millimeters in diameter?
Which type of precipitation is water vapor that condenses into ice crystals in clouds?
Answer:
Which type of precipitation freezes when it comes into contact with a cold surface?
✔ freezing rain
Which type of precipitation is round pellets of ice more than 5 millimeters in diameter?
✔ hail
Which type of precipitation is water vapor that condenses into ice crystals in clouds?
✔ snow
Explanation:
The type of precipitation that freezes when it comes into contact with a cold surface is freezing rain.
The type of precipitation that is round pellets of ice more than 5 millimeters in diameter is hail.
The type of precipitation where water vapor condenses into ice crystals in clouds is snow.
Freezing rain is the rain that is maintained at a temperature that's below freezing by ambient air mass. It's made entirely of liquid droplets.
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how many seconds are in 1 year
Enter the symbol of a sodium ion, Na+
N
a
+
, followed by the formula of a sulfate ion, SO42−
S
O
4
2
−
. Separate the ions with a comma only—spaces are not allowed.
Express your answers as ions separated by a comma.
Answer:
Na⁺,SO₄²⁻
Explanation:
Sodium sulfate is formed by the sodium and sulfate ion.
Sodium is present in group one thus it has only one valence electron. Sodium lose its one valence electron to get complete octet and thus form cation with +1 charge.
On other hand sulfate ion is an anion it carries -2 charge so when it react with sodium there are two sodium atom combine with one sulfate ion inorder to make the compound neutral.
2Na + SO₄²⁻ → Na₂SO₄
Sodium sulfate is actually form when sodium react with sulfuric acid and hydrogen gas is liberated.
Chemical equation:
Na + H₂SO₄ → Na₂SO₄ + H₂
Balance chemical equation:
2Na + H₂SO₄ → Na₂SO₄ + H₂
Which lists three parts of sunlight that make up some of the visible spectrum?
O green, blue, indigo
O infrared, red, orange
ultraviolet infrared, electromagnetic
violet, ultraviolet A ultraviolet B
Brainly if correct Hurry
Answer:
Its A
Explanation:
Green, blue, indigo lists three parts of sunlight that make up some of the visible spectrum. Hence option with green, blue, indigo is correct.
What is Electromagnetic Spectrum ?Electromagnetic spectrum is nothing but the range of wavelengths or frequencies on which electromagnetic radiation extend. it is whole distribution of electromagnetic waves according to frequency or wavelength. Electromagnetic wave is nothing but a photon which carries energy. Photon has frequency, wavelength as well as amplitude.
Electromagnetic spectrum is show in figure.
Range from 4000 angstrom to 7000 angstrom from violet to red respectively shows the visible light
Infrared light is nothing but the heat we feel from the sun. and ultraviolet light is blacked by ozone layer. we can calculate exact value of temperature of the sun rom Stephan's forth power law.
Green, blue, indigo, red and oranges are the colors from visible light, therefore they are part of visible light.
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Based on what you observed on the link above,
describe how ice in a teapot is turned into steam.
Liquid
lid
Answer: the particles in the water heats up and the hotter to gets the faster it moves. When there is no where for the heat to go it builds up and pushes its way out and turns to steam when it hits cool air
Explanation:
Suppose 4.0 g of hydrogen reacts completely with 32.0 g of oxygen to form one product what is the mass of the product?
Answer: The mass of product, [tex]H_2O[/tex] is, 36.0 grams.
Explanation : Given,
Mass of [tex]H_2[/tex] = 4.0 g
Mass of [tex]O_2[/tex] = 32.0 g
Molar mass of [tex]H_2[/tex] = 2 g/mol
Molar mass of [tex]O_2[/tex] = 32 g/mol
First we have to calculate the moles of [tex]H_2[/tex] and [tex]O_2[/tex].
[tex]\text{Moles of }H_2=\frac{\text{Given mass }H_2}{\text{Molar mass }H_2}[/tex]
[tex]\text{Moles of }H_2=\frac{4.0g}{2g/mol}=2.0mol[/tex]
and,
[tex]\text{Moles of }O_2=\frac{\text{Given mass }O_2}{\text{Molar mass }O_2}[/tex]
[tex]\text{Moles of }O_2=\frac{32.0g}{32g/mol}=1.0mol[/tex]
Now we have to calculate the limiting and excess reagent.
The balanced chemical equation is:
[tex]2H_2+O_2\rightarrow 2H_2O[/tex]
From the balanced reaction we conclude that
2 mole of [tex]H_2[/tex] react with 1 mole of [tex]O_2[/tex]
From this we conclude that, there is no limiting and excess reagent.
Now we have to calculate the moles of [tex]H_2O[/tex]
From the reaction, we conclude that
2 moles of [tex]H_2[/tex] react to give 2 moles of [tex]H_2O[/tex]
Now we have to calculate the mass of [tex]H_2O[/tex]
[tex]\text{ Mass of }H_2O=\text{ Moles of }H_2O\times \text{ Molar mass of }H_2O[/tex]
Molar mass of [tex]H_2O[/tex] = 18 g/mole
[tex]\text{ Mass of }H_2O=(2.0moles)\times (18g/mole)=36.0g[/tex]
Therefore, the mass of product, [tex]H_2O[/tex] is, 36.0 grams.
