A sample from a refuse deposit near the Strait of Magellan had 60% of the carbon-14 found in a contemporary living sample. How old was the sample?The half-life of Carbon-14 is 5730 years.
A sample from a refuse deposit near the Strait of Magellan had 60% of the carbon-14 found in a contemporary living sample. We need to determine the age of the sample.Let's assume that the contemporary living sample contains 100 grams of carbon-14. After one half-life, 50 grams of carbon-14 will remain in the sample. After two half-lives, 25 grams of carbon-14 will remain in the sample. This is because carbon-14 undergoes exponential decay.After 3 half-lives, 12.5 grams of carbon-14 will remain in the sample. We can calculate the percentage of carbon-14 remaining by dividing the mass of carbon-14 remaining by the initial mass of carbon-14 in the sample.
after 3 half-lives, the percentage of carbon-14 remaining is:$$\frac{12.5}{100} \times 100 \% = 12.5 \%$$After 4 half-lives, 6.25 grams of carbon-14 will remain in the sample. The percentage of carbon-14 remaining after 4 half-lives is:$$\frac{6.25}{100} \times 100 \% = 6.25 \%$$Therefore, we can use the following equation to determine the age of the sample:$$\% \text{ of carbon-14 remaining} = \left(\frac{1}{2}\right)^n \times 100 \%$$where n is the number of half-lives that have passed. We know that the sample from the refuse deposit had 60% of the carbon-14 found in a contemporary living sample. This means that the sample had 60 grams of carbon-14.Remember that we can use the equation above to calculate the percentage of carbon-14 remaining after n half-lives have passed. So, we can write:$$60 \% = \left(\frac{1}{2}\right)^n \times 100 \%$$Solve for n:$$\begin{aligned} 0.6 &= \left(\frac{1}{2}\right)^n \\ \log_2 0.6 &= \log_2 \left(\frac{1}{2}\right)^n \\ n &= \frac{\log_2 0.6}{\log_2 \frac{1}{2}} \\ n &= 0.73696 \end{aligned}$$The number of half-lives that have passed is approximately 0.73696. We know that each half-life is 5730 years, so we can calculate the age of the sample by multiplying the number of half-lives by the length of one half-life:$$\begin{aligned} \text{age of sample} &= 0.73696 \times 5730 \text{ years} \\ &= 4224.5 \text{ years} \end{aligned}$$Therefore, the sample from the refuse deposit near the Strait of Magellan was approximately 4224.5 years old.
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What’s the answer? I need an answer as soon as possible please!
Answer:
1, 1, 2
Explanation:
1, 1, 2
Does it require more work to raise a 15 kg block by 4 m
or to raise a 20 kg block by 2 m, if both are moving at
a constant velocity? Draw a free-body diagram to help
solve the problem.
The 15 kg block require more work to raise by 4 meter compare to 20 kg blocks .
The free body diagram is attached below,
We know that, Weight \(W=m*g\)
where m is mass of object and g is gravitational acceleration.
Value of \(g=9.8m/s^{2}\)
So that, weight is depend on mass of object.
And , \(workdone=force*distance\)
Work done require to raise 15kg block by 4 m is,
\(W=15*4*g=60g\)
Work done require to raise 20kg block by 2 m is,
\(W=20*2*g=40g\)
Hence, The 15 kg block require more work to raise by 4 meter compare to 20 kg blocks .
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When 2. 0 mol CO2 is heated at a constant pressure of 1. 25 atm, its temperature increases from 250 K to 277 K. Given that the molar heat capacity of CO2 at constant pressure is 37. 11 JK-1mol-1 , calculate q, ∆ H and ∆ U
Answer: See below
Explanation:
\(\mathrm{At \ constant \ pressure \ the \ heat \ generated \ and \ change \ in \ enthalpy \ are \ equal:} \\\begin{aligned}Q &=\Delta H=n C_{p} \Delta T \\&=2 \times(37.11)(277-250) \\&=2003.94 \mathrm{~J} \\Q &=\Delta H=2.0 \times 10^{3} \mathrm{~J}\end{aligned}\)
\(\mathrm{Calculate \ the \ change \ in \ internal \ energy:} \\$$\begin{aligned}\Delta H &=\Delta U+\Delta(P V) \\\Delta U &=\Delta H-n R \Delta T \\&=(2003.94)-(2 \times 8.314 \times(277-250)) \\&=(2003.94)-(448.96) \\\Delta U &=1554.98 \mathrm{~J}\end{aligned}\)
the volume of hydrogen produced at stp was 94.1 ml determine the mass of magnesium required
The mass of the Mg is 0.1 g
What is the stoichiometry of the reaction?Stoichiometry is the quantitative relationship between the reactants and products in a chemical reaction. It involves determining the mole ratios of the reactants and products based on the balanced chemical equation for the reaction.
To find the stoichiometry of a reaction, you need to start with a balanced chemical equation that shows the reactants and products and their respective coefficients. The coefficients in the balanced chemical equation represent the mole ratios of the reactants and products in the reaction.
The equation of the reaction is;
Mg + 2HCl ----> MgCl2 + H2
We know that;
1 mol of the H2 occupies 22400 mL
x moles of H2 occupies 94.1 mL
x = 1 mol * 94.1 mL/ 22400 mL
x = 0.0042 moles
Now;
If 1 mole of Mg produces 1 mole of H2 then 0.0042 moles of Mg is required.
Hence the mass of Mg = 0.0042 moles * 24 g/mol
= 0.1 g
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perform the following mathematical operation, and report the answer to the appropriate number of significant figures 11.65498 +156.325 =?
Answer:
167.97998
Explanation:
A cup of marbles and water is a homogenous mixture / heterogenous mixture. Why?
Answer:
Another example of a homogeneous mixture is salt water. The rock in Figure above is an example of a heterogeneous mixture. A heterogeneous mixture varies in its composition
Explanation:
PLEASE HURRY
Animals respond to external stimuli, such as light, temperature, and danger. Explain what body system is utilized when animals go into fight or flight mode
formula unit of Magnesium oxide and Calcium bicarbonate and aluminum carbonate plzzzz
Magnesium oxide : MgO
Calcium bicarbonate: Ca(HCO3)2
aluminum carbonate: Al2(CO3)3 or C3Al2O9
What is waste good for?
energy for decomposers
being stinky
food chain
A serum sample gave an absorbance of 0.350. Find: the glucose concentration and its calibration sensitivity, and dynamic range. Glucose Concentration, mM Absorbance, A 0.0 0.002 2.0 0.150 4.0 0.294 6.0 0.434 8.0 0.570 10.0 0.704
The glucose concentration for an absorbance of 0.350 is 4.0 mM.
The calibration sensitivity of this sample is 0.144 A/mM, which can be determined by calculating the difference between the absorbance at each glucose concentration and the corresponding glucose concentration divided by the difference in the glucose concentration (0.150 - 0.002 / 2.0 - 0.0 = 0.144).
The dynamic range is the range of glucose concentrations over which the serum sample is accurate, which is from 0.0 mM to 10.0 mM.
This can be determined by looking at the range of glucose concentrations used in the calibration process.
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What mass of silver nitrate (in grams) must be added to precipitate all of the phosphate ions in 45.0 mL of 0.250 M sodium phosphate solution
Approximately 1.91 grams of silver nitrate must be added to precipitate all of the phosphate ions in 45.0 mL of 0.250 M sodium phosphate solution.
To precipitate all of the phosphate ions in 45.0 mL of 0.250 M sodium phosphate solution, the mass of silver nitrate needed can be calculated using stoichiometry and the balanced chemical equation for the reaction between silver nitrate (AgNO₃) and sodium phosphate (Na₃PO₄).
The balanced equation for the reaction is:
3AgNO₃ + Na₃PO₄ -> Ag₃PO₄ + 3NaNO₃
From the equation, it can be seen that one mole of silver nitrate reacts with one mole of sodium phosphate to form one mole of silver phosphate.
First, calculate the number of moles of sodium phosphate in the given volume:
Moles of Na₃PO₄ = Volume (in liters) x Concentration (in M)
= 0.045 L x 0.250 mol/L
= 0.01125 mol
Since the stoichiometry of the reaction is 1:1 between silver nitrate and sodium phosphate, the number of moles of silver nitrate required is also 0.01125 mol.
Finally, calculate the mass of silver nitrate using its molar mass:
Mass = Moles x Molar mass
= 0.01125 mol x 169.87 g/mol (molar mass of AgNO₃)
= 1.91 g (rounded to two decimal places)
Hence, approximately 1.91 grams of silver nitrate must be added to precipitate all of the phosphate ions in the 45.0 mL of 0.250 M sodium phosphate solution.
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Help please, I will give brainliest!! ^^
The picture on the right is after evaporation occurred
Answer:
b molartiary will decrease
Explanation
what is the importance of polar covalent and hydrogen bonds in the structure of water?
Answer:
Water is a remarkable substance, and its unique properties are largely due to the presence of polar covalent bonds and hydrogen bonds in its structure. These characteristics play a crucial role in the physical and chemical properties of water, making it essential for life as we know it.
Explanation:
The polar covalent bonds in water arise from the unequal sharing of electrons between oxygen and hydrogen atoms. This results in the oxygen atom having a partial negative charge (δ-) and the hydrogen atoms having partial positive charges (δ+). These charges create polarity within the water molecule, leading to the formation of hydrogen bonds.
Hydrogen bonds occur when the partially positive hydrogen atom of one water molecule is attracted to the partially negative oxygen atom of another water molecule. These hydrogen bonds are relatively weak individually, but when present in large numbers, they contribute to the cohesion, surface tension, and high boiling point of water.
The importance of these bonds is manifold. The cohesion between water molecules due to hydrogen bonding enables water to form droplets, have a high surface tension, and flow freely, facilitating transport within organisms and in the environment. Additionally, hydrogen bonding leads to the high specific heat capacity and heat of vaporization of water, making it an effective regulator of temperature in living organisms and ensuring stable environmental conditions.
Furthermore, hydrogen bonds play a crucial role in the unique properties of water as a solvent. The polar nature of water allows it to dissolve a wide range of substances, including ionic compounds and polar molecules, facilitating various biological processes such as nutrient transport and chemical reactions in cells.
How does the valence electron configuration (entire last energy level configuration) relate to the group number on the Periodic Table? Use the shorthand notation in your discussion.
Answer:
The valence electron configuration determines the group to which an element belongs to.
Explanation:
The valence electron configuration of an atom of an element refers to the number of electrons in that atoms outermost shell.
The valence electron configuration is related to the group number of an element in that the number of electrons in the valence shell of an atom of an element determines the group to which an element belongs to. For example, all elements having one valence electron belong to group IA of the periodic table. Similarly, all elements having seven valence electrons belong to group VIIA of the periodic table.
This is because, since the reactivity of an element is related to its ability to either gain or lose a certain number of electrons in its valence shell, elements having same number of valence electrons have similar chemical properties.
A compound that has a sea of delocalized electrons has what type of bonding?
Answer:
Metallic Bonding
Explanation:
Metallic Bonding
In metallic bonds, the valence electrons from the s and p orbitals of the interacting metal atoms delocalize. That is to say, instead of orbiting their respective metal atoms, they form a “sea” of electrons that surrounds the positively charged atomic nuclei of the interacting metal ions.
click on the muscle types
cardiac
weak
strong
elbow
skeletal
smooth
Answer:
cardiacskeletalsmoothExplanation:
Cardiac, skeletal and smooth muscles are the three types of muscles.
which of the following characteristics identifies a ph-balanced shampoo
The pH scale ranges from 0 to 14, with values below 7 considered acidic, 7 being neutral, and values above 7 being alkaline. Hair and scalp have a slightly acidic pH, and using a pH-balanced shampoo helps maintain the natural balance.
The characteristic that identifies a pH-balanced shampoo is having a pH level close to the natural pH level of the hair and scalp, which is around 4.5 to 5.5. Therefore, a pH-balanced shampoo will have a pH level in the acidic to neutral range, typically between 4.5 and 5.5, to avoid causing damage or disrupting the natural pH balance of the hair and scalp.
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A pH-balanced shampoo should have a pH between 4.5 and 5.5, contain mild acids or bases, and help to keep the hair and scalp's natural pH level balanced.
Explanation:Characteristics of a pH-balanced shampoo:pH is between 4.5 and 5.5Contains mild acids or bases to maintain the desired pH level Helps to keep the hair and scalp's natural pH level balancedA pH-balanced shampoo is important because it prevents the scalp from becoming too dry or too oily. It ensures that the hair cuticle is closed, reducing frizz and improving shine. Using a pH-balanced shampoo can also help maintain the effectiveness of other hair products.
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Which action happens at the microscopic scale as the temperature of a substance decreases and it eventually freezes?
The speed of the particles rises with the temperature of the solid, liquid, or gas. The particles slow down with decreasing temperature.
A liquid can turn into a solid if it is cooled down far enough.
Why does a liquid become a solid when its temperature drops?The average kinetic energy of the molecules falls as a liquid cools.
The liquid eventually turns into a solid when the quantity of heat removed is sufficient to cause the molecules to be attracted to one another.
Freezing is the process of transitioning from a liquid to a solid.
It loses thermal energy when the liquid cools. Its constituent particles therefore decelerate down and converge.
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QUESTION 3 All of the following are homogeneous mixtures except A. hydrogen gas and chlorine gas. B. sodium chloride and potassium chloride. OC. mercury-zinc solution. OD. hydrochloric acid solution. O E. sodium chloride and potassium chlSride solution.
Answer:
hydrogen gas and chlorine
Explanation:
HCl is a chemical compound and aqueous solution form of HCl is a homogeneous solution
All the following are homogeneous mixtures except hydrogen gas and chlorine gas. Therefore, option A is correct.
What do you mean by homogeneous mixture ?A mixture is said to be homogeneous if its composition is constant throughout. Because the dissolved salt is evenly distributed throughout the whole salt water sample, the salt water described above is homogeneous.
It is single in composition throughout. There is only one phase of matter observed in a homogeneous mixture.
In an aqueous solution of hydrogen chloride gas, water serves as the solvent and the solute, respectively. Hence, hydrogen chloride is a homogeneous mixture rather than a compound.
When hydrogen chloride is dissociated and solvated in water to create hydrochloric acid, it counts as a homogeneous mixture.
Thus, option A is correct.
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What does this weather map symbol represent
A) moving front
B) stationary front
C) cold front
D) warm front
Answer:
B
Explanation:
Blue triangles are a cold front and red bowls are warm front
Stationary front is a combination
HOPE I helped :]
Answer:
stationary front
Explanation:
on a weather map, a stationary front is shown as alternating red semicircles and blue triangles like in the image at the left. notice how the blue triangles point in one direction, and the red semicircles point in the opposite direction.
Another question. What is an example of a chemical change?
Answer:
Yellowing of leaves
Explanation:
Involves the colour change in leaves whereby less amount of chlorophyll is produced
Answer:
burning, cooking, milk becoming curd, rusting of iron
Dry ice changes from a solid to a gas in a process known as A. Melting B. Freezing C.sublimation
Answer:
c
Explanation:
solid to gas directly
how does the strength of the resultant electric field change around like point charges
Answer:
The charge alters that space, causing any other charged object that enters the space to be affected by this field. The strength of the electric field is dependent upon how charged the object creating the field is and upon the distance of separation from the charged objects.
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A 500g sample of Ca-37 decays for 910ms. How much of the original sample remains?
Answer:
15.6 g
Explanation:
Given that;
Mass of original sample = No = 500g
mass of sample remaining at 910 ms = N = ?
time taken to decay= 910 ms
Half life of Ca-37 = 181 milliseconds
From;
N/No = (1/2)^t/t1/2
N/500 = (1/2)^910/181
N/500 = (1/2)^5
N/500 = 1/32
32 N = 500
N = 500/32
N = 15.6 g
In an endothermic reaction, the ______ have more energy than the _______.
A. reactants, products
B. surroundings, products
C. products, reactants
D. reactants, surroundings
Answer:
C
Explanation:
If the products have a higher energy level than the reactants then the reaction is endothermic.
In an endothermic reaction, the reaction mixture absorbs heat from the surroundings. Therefore, the products will have a higher energy than the reactants and ΔH will be positive.
In an exothermic reaction, the reaction mixture releases heat to the surroundings. Therefore, the products will have a lower energy than the reactants and ΔH will be negative.
Evaporator defrosting that involves circulating a heated solution in tubing near and around the evaporator during the off cycle describes a(n) _____ defrost.
Evaporator defrosting that involves circulating a heated solution in tubing near and around the evaporator during the off cycle describes as a No freezing defrost.
Describe defrosting.To preserve their operational effectiveness, refrigerators and freezers often undergo a defrosting treatment regularly. Water vapor from the air condenses on the cooling elements inside the cabinet over time as the door is opened and shut, bringing in the fresh air. Alternately, "defrosting" refers to the act of bringing a frozen product from frozen to a temperature (often above 0°C) where there is no remaining ice. Many times, thawing is simply thought of as the opposite of the freezing process.
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Which system(s) measure time in seconds? (2 Points) Metric System CGS Customary System MKS (multiple answers)
In reaction 1, if we had used 4 grams of NaOH instead of 2 grams, would the heat gained by the solution [#6] have been larger, smaller or the same? Explain Briefly!
If we had used 4 grams of NaOH instead of 2 grams, the heat gained by the solution would have been higher.
What is the enthalpy?The term enthalpy has to do with the heat that could be emitted or evolved in a given reaction. We know that in a neutralization reaction, there is an evolution of heat and as such the reaction vessel would feel warm at the end of the reaction.
Also, the enthalpy would depend on the amount of the limiting reactant. In this case, the limiting reactant would be the sodium hydroxide and as such the enthalpy would affected by a change in the amount of the sodium hydroxide.
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Does fertilizer make a plant grow bigger?mention two variables. How change of one variable effects another one in investigation?
Trick question
Science
In scientific investigations, the effect of fertilizer on plant growth can be studied by examining various variables. Two key variables in this context are the presence or absence of fertilizer (independent variable) and the size or growth of the plant (dependent variable).
When investigating the effect of fertilizer on plant growth, the independent variable is the presence or absence of fertilizer. This variable is controlled by having two groups of plants: one group receiving fertilizer (experimental group) and another group without fertilizer (control group). By comparing the growth of these two groups, we can determine the impact of fertilizer on plant size.
The dependent variable, on the other hand, is the size or growth of the plant. This variable is measured or observed as the outcome of interest. In this case, it would be the height, weight, or overall size of the plants.
By systematically changing the independent variable (presence or absence of fertilizer), we can observe how it affects the dependent variable (plant growth). The experimental group receiving fertilizer is expected to show greater plant growth compared to the control group without fertilizer. This allows us to draw conclusions about the effect of fertilizer on plant growth.
However, it is important to note that the specific outcome may vary depending on other factors such as plant species, soil conditions, and environmental factors. Conducting a controlled experiment while considering these factors helps in obtaining more reliable results.
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If 7.50 g of methane gas (CH4) is in a 3250 mL container at 25° C, what is the pressure
inside the container?
Answer: 10,452 degrees
Explanation: the temperature will rise as more methane is added