Answer:
d. 10 million years
Explanation:
These are the options for the question
Choose one answer.
a. 2.5 million years
b. 5 million years
c. 15 million years
d. 10 million years
✓half-life of the radioactive substance= 5 million years
✓ Then for every 5 million years, original radioactive given (100%) percentage is reduced by factor of 1/2.
✓ 1st 5 million year; After the first 5 million years, the original radioactive is reduced as;
(100%) × 1/2 = 50% remains
✓2nd 5 million year: At 10 millions year, the 50% remaining radioactive is reduced by factor of 1/2
(50%) × 1/2 = 25% remains
Hence, at At 10 millions years 25% of the original radioactive atoms remain
.
Answer:
10 million years
BALANCE THIS CHEMICAL EQUATION PLS, help:)
Answer:
4C₈H₄OH + 35O₂ → 32CO₂ + 10H₂O
Explanation:
The unbalanced reaction expression is given as:
C₈H₄OH + O₂ → CO₂ + H₂O
To solve this problem, we use a mathematical approach.
aC₈H₄OH + bO₂ → cCO₂ + dH₂O
Conserving C: 8a = c
H: 5a = 2d
O: a + 2b = 2c + d
Let a = 1, c = 8, d = [tex]\frac{5}{2}[/tex] , b = 35
4C₈H₄OH + 35O₂ → 32CO₂ + 10H₂O
A phosphate buffer is prepared with KH2PO4 at 0.02 M and K2HPO4 at 0.03 M. What is the concentration of phosphate buffer
Answer:
0.05M is the concentration of the phosphate buffer
Explanation:
A buffer is defined as the aqueous mixture of a weak acid (KH₂PO₄) and its conjugate base (K₂HPO₄). The concentration of this buffer is the sum of the concentrations of the weak acid and the conjugate base, that is:
Concentration of phosphate buffer = 0.02M + 0.03M
=
0.05M is the concentration of the phosphate buffer
Calculate the following to the correct number of signifi- cant figures. Assume that all these numbers are measurements.
(a) x5 17.2 1 65.18 2 2.4
(b) x5 13.0217 17.10
(c) x5 (0.0061020)(2.0092)(1200.00)
Answer:
See below
Explanation:
First, you need to know what a significant figure means.
The significant figures in a measurement consist of all the certain digits in one measurement, including one uncertain or estimated digit.
With that being said, the second thing we need to do is to correct the exercise. According to an external source, the exercise is the following:
a) x = 17.2 + 65.18 - 2.4
In this case, we can say that 17.2 and 2.4 has the uncertain digit at the end, but in 65.18 it's the 8. Therefore, when we make the sum of all of this we have:
x = 17.2 + 65.18 - 2.4 = 79.98
The last digit is the uncertain digit, therefore, we won't include this digit. So the final result would have 3 significant figure. However 8 surpass 5, and hence, we should approximate our result. Then our final result is:
x = 80.0
b) x = 13.0217 / 17.10
The last digit of the 13, is the uncertain. So, doing this:
x = 13.0217 / 17.10 = 0.761502924
With the correct significant figure, this would be only 4 so:
x = 0.7615
c) x = (0.0061020)*(2.0092)*(1200.00)
Applying the same principle as before:
x = (0.0061020)*(2.0092)*(1200.00) = 14.712
Hope it helps
how many electrons are in an atom with the electron configuration of 1s22s22p63s1
Answer:
11
Explanation:
From the question given above, the following data were obtained:
Electronic configuration => 1s²2s²2p⁶3s¹
Number of electrons =?
We must understand that the electronic configuration of an element is written based the number of electrons present in the atom of the element.
To obtain the number of electrons in the atom given in the question above, we simply add up the electrons in each orbital. This can be obtained as follow:
Electronic configuration => 1s²2s²2p⁶3s¹
Number of electrons =?
Number of electrons = 2 + 2 + 6 + 1
Number of electrons = 11
Thus , the number of electrons in the atom is 11
In general, weathering tends to occur more rapidly in warm climates than in cool climates. How does this trend explain the effect of temperature on erosion rates?
Answer:
See explanation
Explanation:
Weathering refers to the breakdown of rocks to form soil. There are several agents of weathering.
In warmer regions, there are more vegetation and microorganisms and they increase the rate of biological weathering.
Since weathering leads to the formation of soil and the rate of weathering is greater in warmer climates, it also follows that as temperature increases and more soil is formed, erosion will happen faster at this higher temperature owing to the presence of more soil compared to colder climates.
There is a huge and direct effect of temperature on the rates of erosion.
The highest rate of weathering occurs in warm and wet climate because in warm and wet climatic regions, more rainfall occurs which increase the rate of weathering. Rainfall and temperature can affect the rate in which rock weathering occurs.
High temperatures and greater rainfall increase the rate of chemical weathering. Rocks in tropical regions exposed to abundant rainfall so we can conclude that hot temperatures weather much faster than similar rocks residing in cold, dry regions.
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How do the valence electrons of an element determine how they will combine with other elements to produce a compound? Please help this is urgent :)
Answer:
See explanation
Explanation:
The valence electrons are electrons found on the valence (outermost) shell of an atom.
When an atoms form compounds, there is an exchange of valence electrons between the atoms of one element and the atoms of another element.
Let us consider a typical example, sodium has one valence electron and chlorine has seven valence electrons. This means that chlorine needs one electron to complete its octet while sodium needs to release one electron in order to attain the octet structure.
So, sodium gives out its one electron and becomes a stable sodium ion and chlorine accepts that electron and becomes a stable chloride ion. This is how the compound sodium chloride is formed.
What are sources of electricity? List as many as you can
Plz Help me plz
Answer:
Solar energy, wind energy, biomass energy.
Explanation:
Identify the Sun activity that travels from one sunspot to another sunspot.
Group of answer choices
Prominence
corona mass ejection
solar wind
solar flare
Answer:
solar flair I think I'm not sure
Vinegar is insoluble in vegatable oil. Does this mean that vinegar is a totally insoluble substance?
Answer:
No
Explanation:
This does not mean that vinegar is insoluble totally. In fact, vinegar is soluble in water because water is a polar solvent.
For a substance to be soluble in another, it must obey the rule of solubility.
The rule states that "like dissolves like"
It implies that polar solvent will only dissolve polar solute.
Also, non-polar solvent will only dissolve non-polar solute.
Vegetable oil is a non-polar solventIt cannot dissolve a polar solute such as vinegarTherefore, the answer is no, vinegar will dissolve in water.
0.8 gram of divalent metal was dissolved in 100 CC of 1.28 N HCl and the solution was diluted to to 200 cc. then 50cc of this solution required 54.6 CC of 0.22N NaOH for the neutralization. find the atomic weight of metal .
Answer:
80g/mol is the molar mass of the metal
Explanation:
A divalent metal M reacts with HCl as follows:
M + 2HCl → MCl₂ + H₂
The excess of HCl is titrated with NaOH. Thus, we can solve the moles of HCl that reacts with the metal and the moles of the metal. As the atomic weight is the ratio between the mass and moles of the atom:
Moles NaOH:
0.0546L * (0.22mol / L) = 0.0120 moles NaOH = Moles HCl in excess
For NaOH and HCl solutions, Normality is the same than molarity.
Moles HCl added:
0.100L * (1.28mol / L) = 0.128 moles HCl * (50mL / 200mL) = 0.032 moles
Moles HCl in that react:
0.032 moles - 0.012 moles = 0.020 moles HCl
Moles M:
0.020 moles HCl * (1mol M / 2 mol HCl) = 0.010 moles M
Molar mass M:
0.8g / 0.010mol =
80g/mol is the molar mass of the metalIdentify the best practices when storing and using drying agents in the lab.
A. Close the drying agent container whenever it is not in active use.
B. Let the drying agent air out before removing it from the container.
C. Wrap the lid of the drying agent container with tape for storage.
D. Only use drying agent that appears clumpy in its original container.
Answer:
A. Close the drying agent container whenever it is not in active use.
C. Wrap the lid of the drying agent container with tape for storage.
Explanation:
Drying agents also known as desiccants are used in pharmaceutical, food and other manufacturing to keep substances dry. These drying agents are anhydrous and hygroscopic. The right usage of these products requires that they are always stored in an air-tight container.
When they are to be removed from a container containing a solvent, they are to be separated by filtration or decanting.
7. You are about to perform some intricate electrical studies on single skeletal muscle fibers from a gastronemius muscle. But first, you must prepare 6L of a 170 mM NaCl solution in which to bath the isolated muscle during your studies. How many grams of NaCl must you weigh out on the lab balance to prepare this bath solution
Answer:
58.61 grams
Explanation:
Taking The molecular weight of NaCl = 58.44 grams/mole
Determine how many grams of NaCl to prepare the bath solution
first we will calculate the moles of NaCl that is contained in 6L of 170 mM of NaCI solution
= ( 6 * 170 ) / 1000
= 1020 / 1000 = 1.020 moles
next
determine how many grams of NaCl
= moles of NaCl * molar mass of NaCl
= 1.020 * 58.44
= 58.61 grams
table salt conducts electricity in water, but sugar does not. Explain why?
Answer:
Because sugar has no ions in the solution
Explanation:
Pure water contains very few ions, so it does not conduct electricity very well. When table salt is dissolved in water, the solution conducts very well, because the solution contains ions. When sugar is dissolved in water, the solution does not conduct electricity, because there are no ions in the solution.
In basic words the more ions in the solution there is a better chance to conduct electricity.
Question 2 of 10 A chemist has a block of copper metal (density is 8.96 g/mL). They drop the metal into a graduated cylinder containing water, and find the volume change is 2.90 mL. What is the mass of the block, in grams? h
Answer:
m = 25.98 g
Explanation:
Given data:
Density of copper metal = 8.96 g/mL
Volume of copper metal block = 2.90 mL
Mass of copper metal block = ?
Solution:
The volume of given block of copper is equal to the volume change of water by adding this block.
Density formula:
d = m/v
by putting values,
8.96 g/mL = m/ 2.90 mL
m = 8.96 g/mL × 2.90 mL
m = 25.98 g
How do molecules bond?
plz answer I will give brainliest
Answer:
Atoms with a positive charge will be attracted to negatively charged atoms to form a molecule. This bonding between atoms is the key to how molecules interact with each other. ... Other molecules interact with water, combining with the atoms to create new soluble liquids.
A copper wire is 44.85 cm long and weighs 1.521 g. The density of copper is 8.933 g/cm3.
What is the radius of the wire in millimeters?
What is the diameter of the wire?
Answer:
i am so sorry
Explanation:
The density of copper is If a sample 8.933 g/cm3. If copper has a volume of 12.993 cm^3. Then the mass will be 136.29 gram.
How can we calculate the mass from density and volume?Density is defined as the mass per unit volume it means that mass present in 1 meter cube is called density. The S.I unit of density is kg/m^3 and in C.G.S it is gram/cm^3
So, In above question can understand that density, mass, and volume all are convert to each other it means that if we know any two variable then third one will be calculated easily.
Mathematically,
Formula for density will be as mentioned below:-
Density = Mass/Volume.
From above formula we can calculate mass which is as follows:-
Mass = Volume × Density.
S.I unit of mass is kilograms and C.G.S unit is gram.
So In above question
Density = 8.933 gram/cm^3
Volume = 12.993 cm^3
So from above formula
Mass = Density × volume
= 10.49 × 12.993
= 136.29 gram
= 0.13629 kilogram
So Mass is equal to 136.29 gram or 0.136 kilograms.
Therefore,The density of copper is If a sample 8.933 g/cm3. If copper has a volume of 12.993 cm^3. Then the mass will be 136.29 gram.
Learn more about density here:
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What is another name for infrared energy? Choose all that apply.
Question 1 options:
Microwave energy
Visible light
Thermal energy
Heat
Answer: not 100% but maybe Visable Light...sorry if thats wrong
Explanation:
Thermal energy is the another name for infrared energy.
What is infrared radiation?Infrared radiation is a type of radiant energy that is not visible to human eyes but we can feel as heat energy.
Infrared radiation (IR), also known as thermal radiation. It is that band of energy in the electromagnetic radiation spectrum with wavelengths between 780 nm and 1 mm so we can conclude that thermal energy is the another name for infrared energy.
Learn more about radiation here: https://brainly.com/question/24524460
What is the charge is the ion when lithium reacts with chlorine
In which way are photosynthesis and cellular respiration different?
Cellular respiration produces oxygen, while photosynthesis uses oxygen.
Cellular respiration is endothermic, while photosynthesis is exothermic.
Photosynthesis uses carbon dioxide, while cellular respiration produces carbon dioxide
Photosynthesis releases energy, while cellular respiration stores energy.
Answer: Photosynthesis uses carbon dioxide, while cellular respiration produces carbon dioxide.
Explanation: i took the test lol
Does the model represent a chemical reaction? (Image)
Answer:
yes it is a chemical reaction
Explanation:
because the substances combined and made something new
How many molecules are in 15 moles of CO2?
There are 90.345 x 10^23 molecules in 15 moles of CO2.
What is Avogadro's number?Avogadro's number is the number of units, atoms or molecules in one mole of a substance which is equals to 6.02214076 × 1023. This number is also known as the Avogadro constant.
This means that one mole of a substance is equals to 6.02214076 × 1023 atoms, ions or molecules then 15 moles is equals to 90.345 x 10^23 molecules so we can conclude that there are 90.345 x 10^23 molecules are in 15 moles of CO2.
Learn more about mole here: brainly.com/question/1427235
= 1
= 2
5
= 3
10
= 6
7
8
Write a balanced half-reaction for the reduction of gaseous oxygen (02) to liquid water
to liquid water (H2O) in acidic aqueous solution. Be sure to add physical state symbols
where appropriate.
a
A balanced half-reaction :
O₂(g)+ 4H⁺(aq)+ 4e⁻⇒2H₂O(l)
Further explanationGiven
Reduction of gaseous oxygen (O₂) to liquid water(H₂O)
Required
A balanced half-reaction
Solution
Step 1 : Equalize the number of elements by adding coefficients
Equates element O
O₂(g)⇒2H₂O(l)
Step 2 : Equalize H by adding H⁺ on the opposite side (the deficient area of H).
O₂(g)+ 4H⁺(aq)⇒2H₂O(l)
Step 3 : Equalized the charge using the addition of electrons (e⁻) along the H⁺ field.
O₂(g)+ 4H⁺(aq)+ 4e⁻⇒2H₂O(l)
Iron and vanadium both have the BCC crystal structure and V forms a substitutional solid solution in Fe for concentrations up to approximately 20 wt.% V at room temperature. Determine the concentration in weight percent of V that must be added to iron to yield a unit cell edge length of 0.289 nm.
Answer:
Explanation:
To find the concentration; let's first compute the average density and the average atomic weight.
For the average density [tex]\rho_{avg}[/tex]; we have:
[tex]\rho_{avg} = \dfrac{100}{ \dfrac{C_{Fe} }{\rho_{Fe}} + \dfrac{C_v}{\rho_v} }[/tex]
The average atomic weight is:
[tex]A_{avg} = \dfrac{100}{ \dfrac{C_{Fe} }{A_{Fe}} + \dfrac{C_v}{A_v} }[/tex]
So; in terms of vanadium, the Concentration of iron is:
[tex]C_{Fe} = 100 - C_v[/tex]
From a unit cell volume [tex]V_c[/tex]
[tex]V_c = \dfrac{n A_{avc}}{\rho_{avc} N_A}[/tex]
where;
[tex]N_A[/tex] = number of Avogadro constant.
SO; replacing [tex]V_c[/tex] with [tex]a^3[/tex] ; [tex]\rho_{avg}[/tex] with [tex]\dfrac{100}{ \dfrac{C_{Fe} }{\rho_{Fe}} + \dfrac{C_v}{\rho_v} }[/tex] ; [tex]A_{avg}[/tex] with [tex]\dfrac{100}{ \dfrac{C_{Fe} }{A_{Fe}} + \dfrac{C_v}{A_v} }[/tex] and
[tex]C_{Fe}[/tex] with [tex]100-C_v[/tex]
Then:
[tex]a^3 = \dfrac { n \Big (\dfrac{100}{[(100-C_v)/A_{Fe} ] + [C_v/A_v]} \Big) } {N_A\Big (\dfrac{100}{[(100-C_v)/\rho_{Fe} ] + [C_v/\rho_v]} \Big) }[/tex]
[tex]a^3 = \dfrac { n \Big (\dfrac{100 \times A_{Fe} \times A_v}{[(100-C_v)A_{v} ] + [C_v/A_Fe]} \Big) } {N_A \Big (\dfrac{100 \times \rho_{Fe} \times \rho_v }{[(100-C_v)/\rho_{v} ] + [C_v \rho_{Fe}]} \Big) }[/tex]
[tex]a^3 = \dfrac { n \Big (\dfrac{100 \times A_{Fe} \times A_v}{[(100A_{v}-C_vA_{v}) ] + [C_vA_Fe]} \Big) } {N_A \Big (\dfrac{100 \times \rho_{Fe} \times \rho_v }{[(100\rho_{v} - C_v \rho_{v}) ] + [C_v \rho_{Fe}]} \Big) }[/tex]
Replacing the values; we have:
[tex](0.289 \times 10^{-7} \ cm)^3 = \dfrac{2 \ atoms/unit \ cell}{6.023 \times 10^{23}} \dfrac{ \dfrac{100 (50.94 \g/mol) (55.84(g/mol)} { 100(50.94 \ g/mol) - C_v(50.94 \ g/mol) + C_v (55.84 \ g/mol) } }{ \dfrac{100 (7.84 \ g/cm^3) (6.0 \ g/cm^3 } { 100(6.0 \ g/cm^3) - C_v(6.0 \ g/cm^3) + C_v (7.84 \ g/cm^3) } }[/tex]
[tex]2.41 \times 10^{-23} = \dfrac{2}{6.023 \times 10^{23} } \dfrac{ \dfrac{100 *50*55.84}{100*50.94 -50.94 C_v +55.84 C_v} }{\dfrac{100 * 7.84 *6}{600-6C_v +7.84 C_v} }[/tex]
[tex]2.41 \times 10^{-23} (\dfrac{4704}{600+1.84 C_v})=3.2 \times 10^{-24} ( \dfrac{284448.96}{5094 +4.9 C_v})[/tex]
[tex]\mathbf{C_v = 9.1 \ wt\%}[/tex]
What is the mass of 3.00 -1023 particles of water? Water has a molar mass of 18.0 g/mol.
3.00 grams
18.0 grams
6.00 grams
9.00 grams
Answer:
bro
Explanation:
guhfuyfouyvyu
Answer:
9.00
Explanation:
I took the test and got it correct ...
The students used 90.0 g/mol as the molar mass of oxalic acid. Use this value to determine how the students calculated the number of moles of oxalic acid present that were completely neutralized by the base.
Answer:
Hi there, the question asked is not complete but not to worry, I will give an explanation that you will be able to solve similar question or the same question when you get the whole question.
Explanation:
Oxalic acid is a diprotic acid and the acid is used with or react with sodium Hydroxide, NaOH in order to determine the molar mass of unknown diprotic acid. Oxalic Acid reacts with sodium as it is given in the balanced chemical reaction below:
(COOH)₂ + 2NaOH ------------------------------------------------------> Na₂C₂O₄ + 2H₂O.
The amount of the oxalic needed is known, say x gram and the molar mass is known. Thus, the number of moles of the oxalic acid= mass/molar mass = x gram/ 90.0 g/mol.
So we say that (COOH)₂ is a primary standard acid which is been used to standardize the base that is Sodium hydroxide.
Then, if we have an unknown diprotic acid, say H₂A, we can react it with NaOH to get the molar mass of the unknown.
H₂A + 2NaOH ---------------------------------------------------------------> Na₂A + 2H₂O.
Therefore, the number of moles of the acid = [concentration of NaOH × volume of NaOH] × [ 1 mole of the acid/ 2 mole of NaOH].
How many moles of hydrogen react with 4.5 moles of oxygen to synthesize water?
Answer:
9moles of hydrogen gas
Explanation:
To solve this problem, we write the reaction expression first;
2H₂ + O₂ → 2H₂O
We have been given the number of moles of oxygen gas to be:
Number of moles of oxygen gas = 4.5moles
From the balanced reaction expression:
1 mole of oxygen gas reacts with 2 moles of hydrogen gas
4.5moles of oxygen gas will react with 4.5 x 2 = 9moles of hydrogen gas
A purified protein is in a HEPES buffer at pH 7.0 with 600 mM NaCl. A 1 mL sample of the protein solution is dialyzed against 1.0 L of the same HEPES buffer with 0 mM NaCl. Once the dialysis has come to equilibrium, what is the concentration (in mM) of NaCl in the protein sample
Answer:
Explanation:
Using the dilution formula to determine the final concentration of NaCl in the protein sample.
[tex]M_1V_1 = M_2V_2[/tex]
[tex]600 \ mM \times 1 \ mL= M_2 \times ( 1000\ mL + 1 \ mL)[/tex]
[tex]M_2= \dfrac{600 \ mM \times 1 \ mL}{ ( 1001\ mL)}[/tex]
[tex]M_2= 0.599 \ mM[/tex]
However, when dialysis attains equilibrium, it implies that the sample was dialyzed twice, SO:
[tex]M_2 = \dfrac{600 \ mM\times 1 \ mL}{201 \ mL} = 2.97 \ mM[/tex]
Now, take the concentration as 2.97 mM
Then:
[tex]M_f = \dfrac{2.985 mM \times 1 mL}{201 \ mL}[/tex]
[tex]M_f = 0.01485 \ mM[/tex]
[NaCl] = 0.01485 mM
In a space shuttle, the Carbon dioxide, CO2 that the crew exhales is removed from the air by a reaction within canisters of Lithium Hydroxide, LiOH. The LiOH is only 85% efficient. On average, each astronaut exhales around 20.0 mol of CO2 every day. What volume of water is produced when the CO2 reacts with the excess LiOH
Answer:
What volume of water is produced when the CO2 reacts with the excess LiOH
X = 360 mL H2O
Explanation:
CO2 (g) + 2 LiOH(s) ⇒ Li2CO3 (aq) + H2O(l)
20.0 mol excess x g
X = 360 mL H2O
x mL H20 = 20.0 mol CO2 (1 mol H2O /1 mol CO2)(18 g H2O/1 mol H2O)
(1 mL H2O /1 g H2O)
X = 360 mL H2O
model of reactants and model of products
H2CO3 → H2O + CO2
Answer:
Kindly check the picture attachment.
Explanation:
H2CO3 --------------------------> H2O + CO2
The reaction above is a decomposition reaction showing how the carbonic acid that is H2CO3 decomposed into H2O and CO2. The study of how reactants react(that is the amount in which they react) in order to form a product (and the amount of product formed) is known as the stoichiometry.
H2CO3 which is the reactant has three oxygen atoms which are all directly bonded to the carbon atom. One of the oxygen atom is bonded doubly to the carbon atom.
CO2 and H2O are the products. The CO2 is linear, O=C=O with the two oxygen atoms bonded doubly each to each carbon atoms. The H2O is bent.
How many significant figures are in 3.20x10^2 g?
Answer:
3
Explanation:
For numbers with decimals, count the number after the decimal.