Answer:
Explanation:
[tex]n=f(t)= \frac{a}{(1+be^{-.9t})}[/tex]
At t = 0
30 = [tex]\frac{a}{1 + b }[/tex]
30 + 30 b = a
[tex]\frac{dn}{dt} =f(t)= \frac{-.9abe^{-.9t}}{(1+be^{-.9t})^2}[/tex]
For t = o
[tex]\frac{dn}{dt} =f(t)= \frac{.9ab}{(1+b)^2}[/tex]
given
24 = [tex]\frac{.9ab}{(1+b)^2}[/tex]
24 = [tex]\frac{30\times.9b }{1+b}[/tex]
24 = 27b / 1 + b
24 + 24 b = 27 b
24 = 3 b
b = 8
a = 30 + 30 x 8 = 270
[tex]n=f(t)= \frac{a}{(1+be^{-.9t})}[/tex]
Put t = infinity
n = a = 270
So at infinite time yeast population will stabilise at number 270 .
12. A 100.00-gram sample of naturally occurring boron
contains 19.78 grams of boron-10 (atomic mass =
10.01 atomic mass units) and 80.22 grams of
boron-11 (atomic mass = 11.01 atomic mass units).
Which numerical setup can be used to determine the
atomic mass of naturally occurring boron?
A) (0.1978)(10.01) + (0.8022)(11.01)
B) (0.8022)(10.01) + (0.1978)(11.01)
C) (0.1978)(10.01)/(0.8022)(11.01)
D) (0.8022)(10.01)/(0.1978)(11.01)
It’s A) (0.1978)(10.01) + (0.8022)(11.01)
Relative and average atomic mass both describe properties of an element related to its different isotopes. Out of these two Relative atomic mas is more accurate. Therefore option A is correct option.
What is mass?Mass defines the quantity of a substance. It is measured in gram or kilogram. Average mass is the mass of atoms of an element that are isotopes. It can be calculated by multiplying mass of a isotope to natural abundance of that isotope.
Mathematically,
average atomic mass= ∑(relative abundance x mass of isotope)
average atomic mass boron= (relative abundance boron-10 x mass of isotope boron-10)+(relative abundance boron-11 x mass of isotope boron-11 )
average atomic mass boron=(0.1978)(10.01) + (0.8022)(11.01)
Therefore option A is correct option.
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1. An atom has 6 protons, 6 neutrons, and 6 electrons. What is the charge of the
atom's nucleus?
A.+6
B.+12
C.-6
D.-18
Answer:
+6
+6
+6
+6
+6
+6answer given
thanks
I need help with my chemistry homework
Speed in excess of 100 km/h, which is 208.8 km / h
Further explanationLinear motion consists of 2: constant velocity motion with constant velocity and uniformly accelerated motion with constant acceleration
• An equation of uniformly accelerated motion
[tex]\large {\boxed {\bold {x=xo+vo.t+\frac {1} {2} at ^ 2}}}[/tex]
vt = vo + at
vt² = vo² + 2a (x-xo)
x = distance on t
vo / vi = initial speed
vt / vf = speed on t / final speed
a = acceleration
I think it's not chemistry but physics
KnownΔx = 290 m
vf = 0⇒stop
Δt = 10 s
We use the formula in the question
[tex]\tt \Delta x=\dfrac{1}{2}(vf+vi)\Delta t\\\\290=\dfrac{1}{2}(0+vi).10\\\\vi=58~m/s=\boxed{\bold{208.8~km/h}}[/tex]
Helpppp
4. This group of substances tend to be malleable, ductile, and have relatively high melting points.
They are
(2 Points)
A.noble gases
B.nonmetals
C.metals
D.halogens
Answer:
The answer is metals
Calculate the volume of a rock that has a mass of 24 g and a density of 8 g/mL
Answer:
24g÷8g/ml=3
volume =3
6. What is one way a star with much more mass than the sun can end up?
white dwarf
red giant
neutron star
red dwarf
Answer:
neutron star
Explanation:
A massive star (More massive than the star) will undergo a supernova explosion. If the remnant of the explosion is 1.4 to about 3 times as massive as our Sun, it will become a neutron star. The core of a massive star that has more than roughly 3 times the mass of our Sun after the explosion will do something quite different
7. The density of gasoline is 0.70 g/cm². How many cm of gasoline have a mass of 80
g?
A 875 cm3
B 88 cm3
C 1,143 cm3
D 114 cm3
Answer Is C 1,143
Explanation:
Is this a chemical reaction? Explain your reasoning. (Will give brainliest)
yes , this is a reaction.
in this sodium hydroxide reacts with copper sulfate
Obi is trying to determine if a powdery, solid substance is an element or a compound. After recording some observations, he strongly heats a sample of the solid over a burner flame. After fifteen minutes, he turns off the flame and allows the sample to cool. He records his final observations in the data table.
Which is the best explanation of his results?
The heating changed some of the sample to gas, causing the mass to decrease without breaking down the sample. Therefore, the original sample is a compound.
The appearance stayed the same, showing that the sample was not broken down by heating. Therefore, the original substance is an element.
The mass decreased during heating and some of the impurities escaped. Therefore, the original substance is an element.
The chemical reaction with acid changed, showing that the sample was broken down by heating. Therefore, the original substance is a compound
Answer: I am thinking C maybe.
Explanation: I don't if this is right but I think it is C.
Answer:
D
Explanation:
Took the test on edge...
A dark blue beaker labeled 100 millimeters Y has an arrow leading to a pale blue beaker labeled 99 millimeters H subscript 2 O. This has an arrow leading to a white beaker labeled 99 millimeters H subscript 2 O. Each arrow has a label 1 milliliter over it. The dark blue beaker has a box below it labeled Beaker number 1. The pale blue beaker has a box below it labeled Beaker number 2. The white beaker has a box below it labeled beaker number 3.
Does taking 1 mL of solution Y (pure bleach) out of the first beaker change the solution’s concentration?
What would the concentration of the second beaker be?
If Beaker #2 is a 1% solution of Y, and Beaker #3 is 1/100th of that in the final solution, what percentage solution would Beaker #3 be?
Answer:
3, 5, 1000
Explanation:
I took the test.
Answer:The first one would be 3
The second is 5
And the last one is 1000
Explanation:
Electron Dot Structures
Draw the electron dot structures for the following elements:
Magnesium (Mg)
Lithium (Li)
Argon (Ar)
Carbon (C)
Sulfur (S)
Helium (He)
Aluminum (Al)
Nitrogen (N)
Silicon (Si)
Hydrogen (H)
Calcium (Ca)
Neon (Ne)
Potassium (K)
Boron (B)
Chlorine (Cl)
Answer:
surf (S)
tide (T)
champion (C)
Explanation:
wag mo nlng pansinin
Explain what intermolecular forces are, and how they are easily overcome.
Explanation:
Intermolecular forces are forces that exist between two or more molecules and they can be overcome at high temperatures.
Which of the following occurs when a liquid becomes a gas
Answer:
Boiling occurs when a liquid changes to a gas below its surface as well as at the surface. The temperature at which a liquid boils is called its boiling point. The opposite of vaporization is called condensation. Sublimation occurs when the surface particles of a solid gain enough energy that they form a gas.Boiling occurs when a liquid changes to a gas below its surface as well as at the surface. The temperature at which a liquid boils is called its boiling point. The opposite of vaporization is called condensation. Sublimation occurs when the surface particles of a solid gain enough energy that they form a gas.Boiling occurs when a liquid changes to a gas below its surface as well as at the surface. The temperature at which a liquid boils is called its boiling point. The opposite of vaporization is called condensation. Sublimation occurs when the surface particles of a solid gain enough energy that they form a gas.Boiling occurs when a liquid changes to a gas below its surface as well as at the surface. The temperature at which a liquid boils is called its boiling point. The opposite of vaporization is called condensation. Sublimation occurs when the surface particles of a solid gain enough energy that they form a gas.
what is the density of an object with a mass of 100 grams and a volume of 50 cm
Answer:
2
Explanation:
because 100÷50=2m÷v=d
Which hypothesis is testable using a scientific experiment?
A. A fried egg is better than a hard-boiled egg.
B. Brown eggs are more attractive than white eggs.
C. Eggs with large yolks are more expensive than eggs with small
yolks.
D. You can boil an egg faster at high altitudes than at sea level.
I think colloids are
heterogeneous
because ____________
___________________
the particles do not dissolve completely..
3. Students were measuring distances and found one to be 2.04 m. When they asked the teacher if their measurement was correct, the teacher said, “Actually, it is 2.16 m.” What is the percent error?
Answer:
5.56
Explanation:
What does it mean for an element to be oxidized?
A. The element is a spectator ion in a chemical reaction.
B. The element has gained one or more electrons in a reaction.
C. The element has lost one or more electrons in a reaction.
D. The element has bonded to another element with opposite charge
Answer:
B
Explanation:
Oxidation occurs when an atom molecule or ion loses one or more electrons in a chemical reaction when oxidation occurs the oxidation state of the chemical species increases oxidation doesn't necessarily involve oxygen originally the term was used when oxygen caused electron loss in a reaction hope this helped. :)
An element is oxidized when It has loses one or more electrons in a chemical reaction. Therefore, Option (C) is correct.
What is Oxidation ?The loss of electrons, gain of oxygen or loss of hydrogen will be considered as Oxidation.
The gain of electrons, loss of oxygen or gain or hydrogen will be considered as the Reduction.
Rusting is one of the popular example of oxidation.
Therefore, An element is said to be oxidized when It has lost one or more electrons in a reaction.
Hence , Option (C) is correct.
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2. Mixtures can be solid, liquid or gas. It can be homogeneous or
heterogeneous and are made up of two or more components. Which of
the following mixtures where components are not visible??
Answer:
A solution is a special type of homogeneous mixture where the ratio of solute to solvent remains the same throughout the solution and the particles are not visible with the naked eye, even if homogenised with multiple sources.
Explanation:
Mixtures can be either homogeneous or heterogeneous': a mixture in which constituents are distributed uniformly is called homogeneous, such as salt in water, otherwise it is called heterogeneous, such as sand in water.
what is the mass of an atom if it has 11 protons, 12 neutrons, and 11 electrons
A,22, B.23, C34, D 11
Answer:
23, B
Explanation:
The mass of an atom is determined by the number of Protons + Neutrons. Here, if we assume the units is AMU (Which means the mass unit for a proton and neutron would be basically 1), the answer would be 11 + 12 = 23 AMU, which is B.
Answer:
B) 23
Explanation:
Relative Mass = number of protons + number of neutrons
Relative Mass = 11 + 12
Relative Mass = 23
How do homes lose thermal energy?
I need TWO reasons on why we want to reduce the thermal loose.
Answer:
Poorly insulated attics, windows not being insulated in the winter
Explanation:
One reason is so we do not get cold in the winter and the reason we have a home is to protect us from the weather or put a shelter above us. Second reason is so we don't get hypothermia in the winter time.
Match each label below with the appropriate term. Note: there may be more than one correct answer.
nonbonding electrons
sigma bond
represents two electrons
Answer: sigma bond
Represents two electrons
Explanation:
E2020
Answer:
Sigma Bond AND Represents two electrons.
Explanation:
what are the strengths and weaknesses of the Mendeleev periodic table?
Answer:
Advantages:
1. Grouping of elements. He generalized the study of the elements then known to a study of mere 8 groups.
2. Gaps for undiscovered elements. Mendeleev left some gaps in his periodic table. These gaps were left for subsequent inclusion of elements not known at that time. He correctly thought that such elements would be discovered later.
3. Prediction of properties of undiscovered elements. He predicted the properties of then unknown elements om the basis of properties of elements lying adjacent to the vacant slots.
4. Incorrect masses corrected. He was able to correct the values of atomic mass of elements like gold and platinum by placing these elements strictly on the bases of similarities in their properties.
Disadvantages:
1. Anomalous pairs: Argon with atomic mass 39.9 precedes potassium with atomic mass 39.1.
Cobalt with atomic mass 58.9 precedes nickel with atomic mass 58.6.
Tellurium with atomic mass 127.6 precedes iodine with atomic mass 126.9.
2. Position of isotopes: According to Mendeleev's periodic law, isotopes of an element must be given separate places in the periodic table since they have different atomic masses. But they were not assigned separate places.
3.Grouping of chemically dissimilar elements: Elements such as copper and silver bear no resemblance to alkali metals but they have placed in separate groups.
4.Separation of chemically similar elements: Elements that are chemically similar, such as gold and platinum have been placed in separate groups.
5.Electron arrangement: It does not explain the electron arrangement of elements.
6. Position of Hydrogen: It was not given in a fixed position.Explanation:
The Mendeleev periodic table has strengths in its predictive power, organization of elements, and observation of periodic trends. However, it has weaknesses in incomplete representation, limited understanding of atomic structure, and challenges in placing rare earth elements.
The Mendeleev periodic table, developed by Dmitri Mendeleev in the 19th century, laid the foundation for the modern periodic table. It has several strengths and weaknesses, which are outlined below:
Strengths of the Mendeleev periodic table:
Predictive Power: One of the major strengths of the Mendeleev periodic table is its ability to predict the existence and properties of yet-to-be-discovered elements. Mendeleev left gaps in the periodic table, accurately predicting the properties of elements that were later discovered and filled in those positions.
Periodic Trends: The Mendeleev periodic table organizes elements in a way that allows for the observation of periodic trends. Elements within the same group (vertical column) exhibit similar chemical properties and have similar valence electron configurations. This periodicity helps in understanding the behavior and reactivity of elements.
Classification of Elements: The Mendeleev periodic table classifies elements based on their atomic number and chemical properties. It provides a systematic arrangement of elements, allowing scientists to organize and study them more efficiently.
Weaknesses of the Mendeleev periodic table:
Incomplete Representation: The Mendeleev periodic table, when initially proposed, had gaps for undiscovered elements. While Mendeleev made accurate predictions, some of the gaps were filled in later with elements that did not necessarily match the properties initially predicted. This incomplete representation can be seen as a weakness.
Limited Understanding of Atomic Structure: At the time of Mendeleev's development of the periodic table, the understanding of atomic structure was incomplete. The periodic table was based on elemental properties without the knowledge of atomic numbers or the electron configuration of elements. This limitation hindered the ability to explain certain observed trends and properties accurately.
Lack of Internal Structure: The Mendeleev periodic table did not provide a detailed understanding of the internal structure of atoms or the arrangement of electrons in energy levels. It primarily focused on organizing elements based on their chemical properties and atomic weights, lacking the underlying atomic structure information.
Rare Earth Element Placement: Mendeleev faced challenges in placing the rare earth elements in the periodic table. Initially, he grouped them together as a separate series, but later refinements led to the placement of the rare earth elements within the main body of the table. The difficulty in organizing these elements reflects a weakness in the early understanding of their properties and arrangement.
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Which of these processes are chemical reactions? Type the correct answer in each box.
Boiling an egg
Crushing spices
veges rotting
chopping veges
dew forming
The metric unit of force is the Newton (N) , which is kg⋅m/s2 .
Convert 10 kg⋅cm/s2 to Newtons.
OPTIONS:
A. 1×10−1 N
B. 1×10−2 N
C. 1×10−5 N
D. 1×10−6 N
Answer:
1×10^-1 N
I took the quiz
Answer:
A
Explanation:
I just took the test.
How many fluorine atoms are present in 6.30 g of C2F4
Fluorine atoms = 1.517 x 10²³
Further explanationThe mole is the number of particles contained in a substance
1 mol = 6.02.10²³
Moles can also be determined from the amount of substance mass and its molar mass
[tex]\large{\boxed{\boxed{\bold{mol=\frac{mass}{molar\:mass}}}}[/tex]
Proust stated the Comparative Law that compounds are formed from elements with the same Mass Comparison so that the compound has a fixed composition of elements
Mass of F[tex]\tt mass~F=\dfrac{4.Ar~F}{MW~C_2F_4}\times mass~C_2F_4\\\\mass~F=\dfrac{4.19}{100}\times 6.3=4.788~gr[/tex]
mol of F[tex]\tt =\dfrac{4.788}{19}=0.252[/tex]
number of Fluorine atoms[tex]\tt 0.252\times 6.02\times 10^{23}=1.517\times 10^{23}[/tex]
What is an indicator? What does it tell you about solutions?
Answer:
Pure water is neutral, and so is petrol. An indicator is a substance that changes colour when it is added to acidic or alkaline solutions. You can prepare homemade indicators from red cabbage or beetroot juice - these will help you see if a solution is acidic or alkaline.
find the oxidation number of carbon in MgCO3
Answer: +2
Explanation: Formula of oxide is MgO, because oxidation state of Mg in MgCO3 is +2.
What do these two changes have in common?
using a large magnet to remove pieces of iron from a junkyard
rain forming in a cloud
Select all that apply.
Both are caused by heating.
Both are only physical changes.
Both conserve mass.
Both are chemical changes.
Answer: Both are only physical changes.
Explanation:
Both are only physical changes.
• The material, which takes part in the change is structurally similar after and before the change is known as the physical change.
• The cloud formation is a physical change as when evaporation of water takes place it goes into the air and produces cloud by the process of condensation. The same water goes back to earth by the process of precipitation and this get repeated again and again.
• A chemical change takes place when formation of new substance takes place by combining two substances. In the case, when a magnet picks up iron in a junkyard, one is still having an iron and a magnet, no formation of substance is taking place. So it is a physical change.
Thus, both the given processes are examples of only physical changes.
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if the gas has a volume of 20 L at a temperature of 25 Celsius what is the volume of the gas when it is heated to 100°C if the pressure remains constant
Answer:
i have no idea
Explanation:
lol
Answer:
this has to do with gas law
Explanation:
Charles law
v1=20
T1=25
V2=?
T2=100
hence V1/T1=V2/T2
V2=V1*T2/T1
V2=20*25/100
V2=5