Answer:
C: They aid in comparison of rock layers at distant locations.
Explanation:
Index fossils are simply fossils of organisms that existed over a wide area and for just a brief duration of time. These fossils help scientists to date rocks and even matching the layers.
Looking at the options, the correct one is Option C.
Answer:
C
Explanation:
EDGE 2022
You dissolve 15.71 g of NH4NO3 in 150.0 mL of solution (call this solution A). You take 20.0 mL of solution A and add water until the total volume is 75.0 mL (call this solution B). You take 15.0 mL of solution B and add 25.0 mL of water to it (call this solution C). You mix 10.0 mL of solution B and 10.0 mL of solution C (call this solution D). What is the concentration of ammonium nitrate in solution D
Answer:
[NH₄NO₃] at D → 0.279 M
Explanation:
This exercise involves a series of dilutions one after the other.
First of all, we calcualte ammonium nitrate's concentration at A.
15.71 g . 1 mol/ 80 g = 0.196 mol / 0.150 mL = 1.31 M
At B → 1.31 M . 20 mL/ 75 mL = 0.349 M
At C → 0.349 M . 15 mL / 25 mL = 0.209 M
[NH₄NO₃] at B = 0.349 M
[NH₄NO₃] at C = 0.209 M
So let's calculate the new moles
In 1 mL of B we have 0.349 mmoles
In 10 mL of B we have 3.49 mmoles
In 1 mL of C we have 0.209 mmoles
In 10 mL of C we have 2.09 mmoles
Volume of D = 10 ml + 10ml = 20 mL
Total mmmoles = 3.49 mmoles + 2.09 mmoles = 5.58 mmoles
[NH₄NO₃] at D = 5.58 mmoles / 20mL → 0.279 M
Because of the magnetic field, magnets do have to touch to affect each other. Question 6 options: True False
Answer:
False, they can interact without touching
1
What is an example of a phenotype?
A having dark hair
B. having dominant genes
C. having recessive genes
D. SS
How many molecules are there in a group that has a mass in grams that is the same
numerically as the mass of the individual molecules in grams?
Answer:
1.00 mole of any element has a mass numerically equal to its atomic mass in grams and contains 6.022×1023 particles.
if you are provided with 34.5 g iron (iii) chloride and 25.3 g sodium carbonate what is the limiting ractant
Answer:
Sodium carbonate, Na₂CO₃ is the limiting
Explanation:
We'll begin by writing the balanced equation for the reaction between iron (iii) chloride, FeCl₃ and sodium carbonate, Na₂CO₃.
This is illustrated below:
2FeCl₃ + 3Na₂CO₃ → Fe₂(CO₃)₃ + 6NaCl
Next, we shall determine the masses of FeCl₃ and Na₂CO₃ that reacted from the balanced equation. This can be obtained as follow:
Molar mass of FeCl₃ = 56 + (3×35.5)
= 56 + 106.5
= 162.5 g/mol
Mass of FeCl₃ from the balanced equation = 2 × 162.5 = 325 g
Molar mass of Na₂CO₃ = (2×23) + 12 + (3×16)
= 46 + 12 + 48
= 106 g/mol
Mass of Na₂CO₃ from the balanced equation = 3 × 106 = 318 g
SUMMARY:
From the balanced equation above,
325 g of FeCl₃ reacted with 318 g of Na₂CO₃.
Finally, we shall determine the limiting reactant. This can be obtained as follow:
From the balanced equation above,
325 g of FeCl₃ reacted with 318 g of Na₂CO₃.
Therefore, 34.5 g of FeCl₃ will react with = (34.5 × 318)/325 = 33.76 g of Na₂CO₃.
From the calculations made above, we can see clearly that it will take a higher amount (i.e 33.76 g) of Na₂CO₃ than what was given (i.e 25.3 g) to react completely with 34.5 g of FeCl₃. Therefore, Na₂CO₃ is the limiting reactant and FeCl₃ is the excess reactant.
Find the atomic mass unit of Silicon-28, Silicon-29, Silicon-30 with masses of 27.977, 28.976, 29.974, respectively.
Answer:
28.085
Explanation:
The formular to obtain average atomic mass unit from isotopes is given as;
sum of (Percentage abundance * Atomic mass) of all isotopes = Average atomic mass unit
Silicon 28 = 92.23%
Silicon 29 = 4.67%
Silicon 30 = 3.1%
(92.23 / 100 * 27.977) + (4.67 / 100 * 28.976) + (3.1 / 100 * 29.974) = Average atomic mass
Average atomic mass = 25.803 + 1.353 + 0.929 = 28.085
2H2 (1) + O2(g) → 2H20 (g)
1. Find the limiting reactant if you start with 30.0 grams of hydrogen and 5.29 grams of oxygen.
2. The actual yield for H2O in the above reaction is 6.72 g, Determine the percent yield for the reaction
when 9.93 grams of hydrogen and excess oxygen react?
Answer: 1. Oxygen is the the limiting reactant.
2. 7.52%
Explanation:
The balanced chemical equation is:
[tex]2H_2(g)+O_2(g)\rightarrow 2H_2O(g)[/tex]
To calculate the moles :
[tex]\text{Moles of solute}=\frac{\text{given mass}}{\text{Molar Mass}}[/tex]
[tex]\text{Moles of} H_2=\frac{30.0g}{2g/mol}=15.0moles[/tex]
[tex]\text{Moles of} O_2=\frac{5.29g}{32g/mol}=0.165moles[/tex]
According to stoichiometry :
1 mole of [tex]O_2[/tex] require = 2 moles of [tex]H_2[/tex]
Thus 0.165 moles of [tex]O_2[/tex] will require=[tex]\frac{2}{1}\times 0.165=0.331moles[/tex] of [tex]NH_3[/tex]
Thus [tex]O_2[/tex] is the limiting reagent as it limits the formation of product and [tex]H_2[/tex] is the excess reagent.
2. [tex]\text{Moles of} H_2=\frac{9.93g}{2g/mol}=4.96moles[/tex]
[tex]\text{Moles of} H_2O=\frac{6.72g}{18g/mol}=0.373moles[/tex]
As 2 moles of [tex]H_2[/tex] give = 2 moles of [tex]H_2O[/tex]
Thus 4.96 moles of [tex]H_2[/tex] give =[tex]\frac{2}{2}\times 4.96=4.96moles[/tex] of [tex]H_2O[/tex]
percentage yield = [tex]\frac{\text {actual yield}}{\text {theoretical yield}}=\frac{0.373}{4.96}\times 100=7.52\%[/tex]
Thus the percent yield for the reaction is 7.52%
Cl2+2KI→2KCl + I2 is an example of which type of reaction?
Question 1 options:
decomposition
combination
combustion
single replacement
Answer:
single replacement
Explanation:
I took the test :)
Cl₂ + 2KI → 2KCl + I₂ is an example of single replacement reaction. Therefore, option D is correct.
What is an single replacement reaction ?A single-replacement reaction is a chemical reaction in which one element replaces by the another in a compound. The general equation is. A + BC ⇒ AC + B.
An example of a single replacement reaction occurs when the element potassium reacts with water, then the colorless solid compound potassium hydroxide formed, and hydrogen gas is release. The equation for this reaction is as follows:
2K + 2H2O ⇒ 2KOH + H.
There are three main types of single replacement reactions are metal replacement, hydrogen replacement and halogen replacement reaction.
Thus, option D is correct.
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In a typical mass spectrum, a smaller signal is observed at a mass 1 amu higher than the molecular ion peak. Why
Answer:
Answer is explained below in the explanation section
Explanation:
Smaller signal is observed at a mass 1 amu because small percentage of the compound will have carbon isotope of 13C instead of 12C.
As we know, mass spectrometry is done as a small compound is first vaporized and then bombarded to ionize it. And then, those ions are accelerated forward and then at some point ions are separated and deflected by the application of magnetic field.
And finally hits the detector to give us a spectrum to read. So, in this whole procedure, there can be a small percentage of carbon isotope of 13C instead of 12C in that compound and showed in the spectrum as a smaller signal at a mass 1 amu.
Two 4-grams paper towels are identical except for their thermal energies. Which paper towel has a higher temperature.
a- The paper towel with more thermal energy
b- The paper towel with less thermal energy
pls answer
Answer:
a- The paper towel with more thermal energy
Explanation:
The paper towel with a higher temperature is one with more thermal energy.
Temperature is the degree of hotness or coldness of a body. And it is a measure of the average kinetic energy of the particles within a medium or body.
As body gains more thermal energy which is a form of kinetic energy, the average kinetic energy of its particles increases.
This will in turn lead to an increase in the temperature of the substance.
So, the paper towel with more thermal energy will have a higher temperature.
What do we call the study of weather? A.forcasting B.meteorology
The correct answer is B. meteorology. The study of weather is called meteorology, derived from the Greek word for "of the atmosphere".
Gallium (Ga) consists of two naturally occurring isotopes with masses of 68.926 and 70.925 amu. (a) How many protons and neutrons are in the nucleus of each isotope
Answer:
[tex]neutrons_{Ga-69}=38\\\\neutrons_{Ga-71}=40[/tex]
Explanation:
Hello!
In this case, since isotopes of the same element have the same number of protons and electrons but different atomic mass, we can compute the number of neutrons by subtracting the number of protons to the atomic mass of the isotope; thus, for Ga-69 and Ga-71 (rounded up to whole numbers), we obtain:
[tex]neutrons_{Ga-69}=69-31=38\\\\neutrons_{Ga-71}=71-31=40[/tex]
Best regards!
How does ocean temperatures very around the globe?
PLZ HELP ME
Answer:
As the oceans absorb more heat, sea surface temperature increases and the ocean circulation patterns that transport warm and cold water around the globe change
Explanation:
how to remove acetone from a school chromebook
Answer:
Apply some dishwashing solution with a white washcloth to the acetone residue and for a few minutes, work in gently from the edges of the spill to the center. Dont rub. Continue until the spill is completely removed.
HELP
How many grams are in 2.500 mol of magnesium hydroxide?
58.33 g
0.04286 g
145.8 g
100.8 g
23.33 g
Answer:
145.8g
Explanation:
Given parameters:
Number of moles of magnesium hydroxide = 2.5mol
Unknown:
Mass of Mg(OH)₂ = ?
Solution:
To solve this problem we use the expression below;
Mass of Mg(OH)₂ = number of moles x molar mass
Molar mass of Mg(OH)₂ = 24.3 + 2(16 + 1) = 58.3g/mol
Mass of Mg(OH)₂ = 2.5 x 58.3 = 145.8g
3. Which type of pitch do you think was
thrown in the following situation?
A pitcher throws a pitch that looks like
a fastball but travels a little slower. The
batter swings too early, expecting a
fastball.
A. Change-up
B. Slider
C. Fastball
D. Curveball
In 42 hrs, 4.32 g of argon-35 decay to leave only 0.54 g. What is the half-life of argon-
35?
o 21 hrs
O 7 hrs
O 84 hrs
14 hrs
Answer:
14 hrs.
Explanation:
From the question given above, the following data were obtained:
Time (t) = 42 hrs
Original amount (N₀) = 4.32 g
Amount remaining (N) = 0.54 g
Half-life (t½) =…?
Next, we shall determine number of half-lives required for 4.32 g of the isotope to decay to 0.54 g. This can be obtained as follow:
Original amount (N₀) = 4.32 g
Amount remaining (N) = 0.54 g
Number of half-lives (n) =?
N = 1/2ⁿ × N₀
0.54 = 1/2ⁿ × 4.32
Cross multiply
0.54 × 2ⁿ = 4.32
Divide both side by 0.54
2ⁿ = 4.32 / 0.54
2ⁿ = 8
Express 8 in index form with 2 as the base
2ⁿ = 2³
n = 3
Thus, it took 3 half lives for 4.32 g of the isotope to decay to 0.54 g.
Finally, we shall determine the half-life of the isotope. This can be obtained as follow:
Time (t) = 42 h
Number of half-lives (n) = 3
Half-life (t½) =
n × t½ = t
3 × t½ = 42
Divide both side by 3
t½ = 42 / 3
t½ = 14 hrs
Thus, the half-life of the isotope is 14 hrs
I need help on this question
Answer:
warm blooded
Explanation:
humans are warm blooded. we cannot change our body temperature as we want to
If data comes in that disproves a theory, what will happen to the theory?
Answer: More conservative scientists will try to modify the existing theory to fit the new data. The last answer, the fourth one.
Explanation: I think I had this question before, hope it helps!
At rest, a neuron has a lower concentration of sodium than the surrounding fluid. The neuron also has a higher concentration of potassium inside the cell. The sodium-potassium ion pump is used to maintain the neuron in the resting state. Which of the following statements is true?
a. Remaining at rest requires the use of ATP.
b. Remaining at rest requires an input of sodium.
c. Remaining at rest requires the activation of cotransporters.
d. Remaining at rest requires decreased permeability of the membrane.
Answer:
a. Remaining at rest requires the use of ATP.
Explanation:
The resting membrane potential is maintained by the sodium-potassium pump. The sodium potassium pump does this by actively pumping sodium ions out of the cell and potassium ions inside the cell in a ratio of 3:2. This movement of ions by the sodium-potassium pump is against their concentration gradient. In a neuron at rest, there are more sodium ions outside the cell than there are inside the cell. Also, there are are more potassium ions inside the cell than there are outside the cell. However, there are ion channels through which these ions enter and leave the cell. Sodium ion channels allow sodium to enter the cell following its concentration gradient, whereas, potassium ion channels allow potassium to leave the cell following its concentration gradient. However, more potassium ions leave the cell than do sodium ions enter the cell because of the higher permeability of the cell to potassium ions.
In order to maintain the resting membrane potential, the sodium potassium pump powered by the hydrolysis of an ATP molecules pumps sodium ions out of the cell and potassium ions into the cell.
Therefore, the correct option is A, as ATP is needed by the sodium-potassium pump in order to maintain the resting membrane potential.
Calculate the mass of nitrogen dissolved at room temperature in an 93.0 LL home aquarium. Assume a total pressure of 1.0 atmatm and a mole fraction for nitrogen of 0.78.
Answer:
84.6g of nitrogen is the mass dissolved in a home aquarium
Explanation:
Using combined gas law:
PV = nRT
We can solve for the mass of nitrogen solving the total moles of the aquarium and with the mole fraction as follows:
P = 1.0atm
V = 93.0L
R = 0.082atmL/molK
T = 20°C + 273.15 = 293.15K Assuming room temperature as 20°C
PV / RT = n
1.0atm*93.0L / 0.082atmL/molK*293.15K
3.87 = moles of gas
As mole fraction of nitrogen in the air is 0.78, moles of nitrogen are:
3.87 * 0.78 = 3.02moles of nitrogen
As molar mass of nitrogen gas, N₂, is 28g/mol:
3.02 mol N₂ * (28g / mol) =
84.6g of nitrogen is the mass dissolved in a home aquariumA 232 mL cup of whole milk contains about 27 mg of cholesterol. Express the cholesterol concentration of the milk in kilograms per cubic meter (kg/m3).
cholesterol concentration: kg/m^3
Explanation:
Cholesterol concentration = 27 mg/ 232 mL
Change unit mg/ml to kg/m³
1 kg = 1000 g
1 g = 1000 mg
1 kg = 1000000 mg
1 kg = 10⁶ mg
10⁶ mg = 1 kg
1 mg = 10^-6 kg
m³ = 1000 L
1 L = 1000 mL
m³ = 1000000 mL
m³ = 10⁶ mL
10⁶ mL = m³
1 mL = 10^-6 m³
Cholesterol concentration = 27 mg/ 232 mL
27 × 10^-6 kg/ 232 × 10^-6 m³
= 27/232 kg/m³
What does the interquartile range represent?
A
the lower 50 percent of the data
B
the higher 50 percent of the data
C
the middle 50 percent of the data
D
the middle data point
Answer: C) middle 50 percent of the data
The interquartile range (IQR) spans from the first quartile Q1 to the third quartile Q3.
25% of the data is below Q1 and 75% of the data is below Q3. The gap between the two endpoints consists of 75-25 = 50 percent of the data, or half of the data.
The middle 50 percent of the data. Therefore, option (C) is correct.
The interquartile range (IQR) shows the spread or dispersion of a dataset. It is calculated as the difference between the third quartile (Q3) and the first quartile (Q1) in a sorted dataset. The first quartile (Q1) is the value below which 25 percent of the data falls, and the third quartile (Q3) is the value below which 75 percent of the data falls.
The interquartile range captures the range of the central 50 percent of the data. It provides a measure of the variability or spread of the middle portion of the dataset while excluding the influence of extreme values or outliers.
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In what element will metallic bonding occur?
A.
Carbon
B.
Oxygen
C.
Argon
D.
Cobalt
what are three components that make a complete description of a location?
Answer:
Distance, direction and symbol.
Explanation:
Distance, direction and symbol are the three components of the map which make a complete description of a location. On the map, these three components are present which provides information about a specific location on the map. Map is a drawing on the paper that shows the geography of the whole world and provides information in detail.
Given the equation representing a reaction:
H + H -----> H2
Which statement best describes the energy change in this reaction?
A. a bond is broken as energy is absorbed
B. a bond is broken as energy is released
C. a bond is formed as energy is formed
D. a bond is formed as energy is released
Answer:
(4) A bond is formed as energy is released.
Explanation:
Quizlet
A bond is formed as energy is released best describes the energy change in
the reaction.
Hydrogen atoms share their electrons to form a hydrogen molecule( H₂) .
Covalent bonds are the types of bonds formed when it occurs.
The formation of the bond results in energy being released. On the other
breaking of bonds involves energy to be absorbed. The stated facts
confirms D as the most appropriate choice.
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Smallest particle of a substance that can retain its properties & is
composed of one or more atoms *
O A. Atom
O B. Molecules
O C. Matter
O D. Everything
Answer:
Molecules
Explanation:
He has an atomic number of 2. The number of __________________equals the number of
______________, it has ____ electrons.
Answer:
1- Hélium
2-protons
3-Electrons
4-2
Respectively thx
Select the atoms that belong to the same element.
Answer:
the middle and bottom left
Explanation:
one is a positively charged atom, and the other is normal. they are both the same
Answer:
the middle and bottom left .
Severe or sudden changes in Earth's atmosphere can cause entire species of animals to die. When all of the members of species die out, it is called
Answer: Extinction
Animals on the verge of extinction are considered endangered species. Some could argue that the phrasing "threatened" is synonymous to "endangered". Some classify extinction based on if the species is completely wiped out in the wild, or if the species is completely gone (both in the wild and in zoos for instance). Extinction events are not solely due to the changes in atmosphere, but also due to lack of food or habitat, among other possible factors.
