Answer: c
Explanation:
Answer: C - Centuries
Explanation:
Which of the following describes a chemical change?
A. a suspension of corn starch and water
B. formation of a precipitate
C. formation of a solution
D. filtration of a solid from a liquid
Answer:
C
Explanation:
Have a nice day
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:
What is the volume of 12.0 M NaOH needed to prepare 5.00 L of a 2.50 M NaOH solution? What volume of water (solvent) is required to make this dilution? Please show work
Answer:
Approximately [tex]1.04\; \rm L[/tex] of the [tex]12.0\; \rm M[/tex] [tex]\rm NaOH[/tex] solution is needed. Approximately another [tex]3.96\; \rm L[/tex] of water will also be required.
Assumption: the volume of these [tex]\rm NaOH[/tex] solutions does not depend on the quantity of [tex]\rm NaOH\![/tex] (the solute) that each of them contain.
Explanation:
Calculate the number of moles of [tex]\rm NaOH[/tex] formula units in that [tex]5.00\; \rm L[/tex] of [tex]2.50\; \rm M[/tex] [tex]\rm NaOH\![/tex] solution:
[tex]n(\mathrm{NaOH}) = c\cdot V = 5.00\; \rm L \times 2.50\; \rm mol \cdot L^{-1} = 12.5\; \rm mol[/tex].
Calculate the volume of a [tex]12.0\; \rm M[/tex] [tex]\rm NaOH[/tex] with that many [tex]\rm NaOH\![/tex] formula units:
[tex]\displaystyle V = \frac{n}{c} = \frac{12.5\;\rm mol}{12.0\; \rm mol \cdot L^{-1}}\approx 1.04\;\rm L[/tex].
That should be the volume of the [tex]12.0\; \rm M[/tex] [tex]\rm NaOH[/tex] solution needed to prepare that [tex]5.00\; \rm L[/tex] of [tex]2.50\; \rm M[/tex] [tex]\rm NaOH\![/tex] solution. However, [tex]1.04\; \rm L[/tex] corresponds to only about one-fifth the volume of a [tex]5.00\; \rm L\![/tex] solution. The difference in volume should be filled with pure water:
[tex]\begin{aligned}V(\text{water}) &\approx 5.00\; \rm L - 1.04\; \rm L = 3.96\; \rm L\end{aligned}[/tex].
what is the ph of blood
Answer:
7.35 to 7.45
Explanation:
According to healthline.com, the average pH of blood is 7.35 to 7.45.
How might sediment be a good thing?
Answer: Sediment is important because it often enriches the soil with nutrients. Areas rich in sediments are often also rich in biodiversity. Sedimentary soil is usually better for farming. Deltas and river banks, where much sediment is deposited, are often the most fertile agricultural areas in a region.
Which of the following could result from a substance that undergoes a physical change
Answer:
B. It undergoes phase change.
Explanation:
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.
If you weigh 118 lbs, how many kilograms is this
Answer:
the answer is 53.524 kg
is sugar an element or a compound
Answer:
it is a compound
Explanation: i have it on a test
You add 168.90 grams of NaCl to a container and then you add 616.00 grams of water to that same container What is the weight percent of NaCl in the containerI
Answer:
The weight percent of NaCl in the container is 21.5%
Explanation:
Given that,
Mass of NaCl = 168.90 gram
Mass of water = 616.00 grams
We need to calculate the weight percent of NaCl in the container
Using formula of percentage of weight
[tex]weight\ \%\ of\ component\ of\ the\ solution =\dfrac{weight\ of\ the\ component\ in\ the\ solution}{total\ weight\ of\ the\ solution}\times100[/tex]
Put the value into the formula
[tex]weight\ \%\ of\ component\ of\ the\ solution =\dfrac{168.90}{168.90+616.00}\times100[/tex]
[tex]weight\ \%\ of\ component\ of\ the\ solution=21.5\%[/tex]
Hence, The weight percent of NaCl in the container is 21.5%
Something used to represent a complex idea or process in science is a what
Answer:
a model?
Explanation:
im not sure! i think so
Answer:
Yes, It is a model
Explanation:
A complex idea or a process can be demonstarated by using a Model because you can see things easier and its basically a copy of anything from forests to volcanoes but smaller to make it easier to see.
Hope This Helps
What makes metals, in particular, good conductors of electricity?
A.
the ability of electrons to flow throughout the metal
OB.
the absence of charged particles
O c.
the high temperatures required to break metallic bonds
D.
the presence of positive and negative ions
Answer: I believe the answer is A
2.56 g of hydrogen reacts completely with 20.32 g of oxygen
to form X g of water. X = g
Answer:
Mass of water produced is 22.86 g.
Explanation:
Given data:
Mass of hydrogen = 2.56 g
Mass of oxygen = 20.32 g
Mass of water = ?
Solution:
Chemical equation:
2H₂ + O₂ → 2H₂O
Number of moles of oxygen:
Number of moles = mass/ molar mass
Number of moles = 20.32 g/ 32 g/mol
Number of moles = 0.635 mol
Number of moles of hydrogen:
Number of moles = mass/ molar mass
Number of moles = 2.56 g/ 2 g/mol
Number of moles = 1.28 mol
Now we will compare the moles of water with oxygen and hydrogen.
O₂ : H₂O
1 : 2
0.635 ; 2×0.635 = 1.27
H₂ : H₂O
2 : 2
1.28 : 1.28
The number of moles of water produced by oxygen are less thus it will be limiting reactant.
Mass of water produced:
Mass = number of moles × molar mass
Mass = 1.27 × 18 g/mol
Mass = 22.86 g
Answer:
22.88
Explanation:
correct have a g'day mate
How many atoms of copper are in 0.137g of copper?
The total energy in an isolated system is conserved.
True or false?
Answer:
true
Explanation:
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.
adding hot water to your cold bath water is
conduction
convection
radiation
Answer:convection
Explanation:
Answer: B. Convection
Explanation: I hope this helps! :)
what makes an element reactive
Answer:
The number of electrons in the outermost shell of an atom determines its reactivity.
Explanation:
Answer:
The number of electrons in the outermost shell of an atom determines its reactivity. Noble gases have low reactivity because they have full electron shells. Halogens are highly reactive because they readily gain an electron to fill their outermost shell.
Explanation:
We can see water change state, from ice to steam. This is a ———-
change in matter.
A)
chemical
B)
combustion
C)
physical
D)
solubility
Answer:
C
Explanation:
its physical change.
* 20 POINTS
A ________ is made of two or more elements chemically combined.
a.
alloy
b.
mixture
c.
element
d.
compound
Answer:
Compound is the answer
A chemist needs to create a series of standard Cu2+(aq) solutions for an absorbance experiment. For the first standard, he uses a pipet to transfer 10.00 mL of a 2.61 M Cu2+(aq) stock solution to a 250.0 mL volumetric flask, and he adds enough water to dilute to the mark. He then uses a second pipet to transfer 10.00 mL of the second solution to a 100.0 mL volumetric flask, and he adds enough water to dilute to the mark. Calculate the concentration of the Cu2+(aq) solution in the 100.0 mL volumetric flask. concentration: M
Answer:
0.01 M
Explanation:
The chemist is performing a serial dilution in order tyo obtain the calibration curve for the instrument.
First we must obtain the concentration of the solution in the 250ml flask from
C1V1 = C2V2
Where;
C1 = concentration of the stock solution
V1 = volume of the stock solution
C2 = concentration of the diluted solution
V2= volume of the diluted solution
2.61 × 10 = C2 × 250
C2 = 2.61 × 10/250
C2 = 0.1 M
Hence for solution in 100ml flask;
0.1 × 10 = C2 × 100
C2 = 0.1 × 10/100
C2 = 0.01 M
Question 3 of 8
Which two characteristics are needed to describe a force?
A. Direction
B. Speed
C. Resistance
D. Size
SUBT
Answer:A. Direction
C. Resistance
Explanation:
Forces are due to an interaction of at least two objects. It may change the state of motion of an object. It may change the shape of an object. Forces applied on an object in the same direction add to one another and the resultant is in the same direction.
plz mark brainliest
Be sure to answer all parts. Consider the reaction 2SO2(g) + O2(g) ⇌ 2SO3(g)ΔH = −198.2 kJ/mol How would the concentrations of SO2, O2, and SO3 at equilibrium change if we were to (a) increase the temperature? [SO2]: The concentration increases. The concentration decreases. There is no change. [O2]: The concentration increases. The concentration decreases. There is no change. [SO3]: The concentration increases. The concentration decreases. There is no change. (b) increase the pressure and decrease the volume? [SO2]: The concentration increases. The concentration decreases. There is no change. [O2]: The concentration increases. The concentration decreases. There is no change. [SO3]: The concentration increases. The concentration decreases. There is no change. (c) add a catalyst? [SO2]: The concentration increases. The concentration decreases. There is no change. [O2]: The concentration increases. The concentration decreases. There is no change. [SO3]: The concentration increases. The concentration decreases. There is no change.
Answer:
a)
[SO2]: The concentration increases
[O2]: The concentration increases.
[SO3]: The concentration decreases.
b)
[SO2]: The concentration decreases.
[O2]: The concentration decreases.
[SO3]: The concentration increases.
c)
[SO2]:There is no change.
[O2]: There is no change.
[SO3]: There is no change
Explanation:
For an exothermic reaction, increase in temperature decreases the concentration of products and increases the concentration of reactants since increase in temperature shifts the equilibrium position to the left hand side.
Increase in pressure and decrease in volume will shift the equilibrium position towards the right hand side which means more SO3 in the system.
Catalyst increases the rate of forward and reverse reaction simultaneously hence at equilibrium, the concentration of reactants and products remain unchanged.
why is earth often referd as a blue planet ?
A-When viewed from space, the biosphere always looks blue.
B-Most people like blue.
C-The sky is blue.
D-The hydrosphere looks blue and covers three-fourths of the Earth’s surface.
NEED ANSWER ASAP
Answer:
D-The hydrosphere looks blue and covers three-fourths of the Earth’s surface.
Explanation:
Define energy transformation.
Answer:
Enery transformation is when a forn of energy changes into another.
Explanation:
An example of this would be a lamp. The lamp gets its energy through electricity. This electricity is later turned into light energy. Electrical energy to light evegy.
(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
Learn more : https://brainly.com/question/13531301
3. True or False. A compound is formed when two or more elements are
False
True
Which of the four models represents a solid
Answer:
is there an image
Explanation:
the object in question 1 has a mass of 21.535g. what metal is the cylinder most likely made of? why? pls help asap!!
Answer:
Aluminium
Explanation:
From the question given above, the following data were obtained:
Diameter (d) = 1.25 cm
Height (h) = 6.48 cm
Volume (V) of cylindrical=.?
Mass (m) of cylindrical object = 21.535 g
Density of the cylindrical object =..?
Next, we shall determine the radius of the cylindrical object. This is illustrated below:
Diameter (d) = 1.25 cm
Radius (r) =?
r = d/2
r = 1.25/2
Radius (r) = 0.625 cm
Next, we shall determine the volume of the cylindrical object. This can be obtained as follow:
Height (h) = 6.48 cm
Radius (r) = 0.625 cm
Pi (π) = 3.14
Volume (V) of cylindrical=.?
V = πr²h
V = 3.14 × 0.625² × 6.48
V = 7.948 cm³
Recall:
1 cm³ = 1 mL
Therefore
7.948 cm³ = 7.948 mL
Thus, the volume of the cylindrical object is 7.948 mL
Finally, we shall determine the metal in which the cylindrical object is made up of by calculating the density of the cylindrical object. This can be obtained as follow:
Mass (m) of cylindrical object = 21.535 g
Volume of the cylindrical object = 7.948 mL
Density of cylindrical object =?
Density = mass /volume
Density = 21.535 / 7.948
Density of cylindrical object = 2.7 g/mL
Comparing the density of the cylindrical object (i.e 2.7 g/mL) with those given in the table in the question, the cylindrical object is made of aluminium since they have the same density.
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