Answer:
768g
Explanation:
We can use to formula [tex]N(A) = N_0(\frac{1}{2})^\frac{t}{t_{1/2}}[/tex] . Here, N(A) is the final amount. N0 is the initial amount. t is the time elapsed, and [tex]t_{1/2}[/tex] is the half life. Plugging in, we get the answer above.
The half life of I -137 is 8.07 days. if 24 grams are left after 40.35 days, 800 gram were in the original sample.
What is half life?The half-life (symbol t12) is the amount of time it takes for a volume (of material) to be reduced to half of its original value. In nuclear physics, the phrase is typically used to indicate how rapidly unstable atoms experience radioactive decay or even how long stable nuclei survive.
The phrase is sometimes used more broadly to describe any form of exponential (or, in rare cases, non-exponential) decay. The biological ½ of medications and other compounds in the human body, for example, is referred to in the medical sciences. In exponential growth, the inverse of half-life is doubling time.
ln P = kt + C
P = amount of I-137 at time t
C = constant
k = 1/time
t = time
1st condition:
P = Po, t = 0 days
2nd condition: (half-life)
P = 0.5Po, t = 8.07 days
3rd condition:
P = 25 grams, t = 40.35 days
Po = 800 grams
mass of I-137 = 800 gram
Therefore, 800 gram were in the original sample.
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1. What is the problem in this activity?
2. Formulate your hypothesis. (List down at least 3 hypotheses)
3. What is the dependent variable?
4. What is the independent variable?
5. Analyze your results. Which type of liquid will prevent the apple from
turning brown?
a. lemon
b. milk
Hello. You forgot to say that this question is about the possibility of using some type of product that prevents cut apples from becoming darker.
Answer and Explanation:
1. The problem with this activity is "What can you put on an apple slice to keep it from turning brown?" The problem in a scientific experiment is the element that provides a question about what is being observed.
2. Hypotheses are assumptions made about what was observed, in addition, hypotheses can answer the question shown in the problem. In the case of apples, the hypotheses can be: "Lemon juice is the most efficient product in delaying the blackening of cut apples." "Water is inefficient in preventing blackened cut apples." "Milk accelerates the blackness of cut apples."
3. The dependent viable is one that needs to be influenced by another element to bring about a result. In the case of the experiment with apples, the dependent variable is the blackening rate of the apple slices.
4. The independent variable, on the other hand, refers to the element that does not need any influence to cause a result, on the contrary, this variable acts on the dependent variable, influencing it. In the case of this experiment, the independent variable is the types of liquid tested to delay the blackening of cut apples.
5. Lemon was the most efficient liquid. Probably this efficiency is related to the lemon's ability to decrease the strength of antioxidants, due to its very low pH.
Consider the balanced equation below. Upper P Upper C l Subscript 3 Baseline + Upper C l Subscript 2 Baseline right arrow Upper P Upper C l Subscript 5. What is the mole ratio of PCl3 to PCl5? 1:1 2:1 3:5 5:3
Answer : The mole ratio of [tex]PCl_3[/tex] to [tex]PCl_5[/tex] is 1 : 1.
Explanation :
Balanced chemical reaction : It is a chemical reaction in which the number of atoms of individual elements present on reactant side must be equal to the product side.
The balanced chemical reaction is:
[tex]PCl_3+Cl_2\rightarrow PCl_5[/tex]
By the stoichiometry of the reaction we can say that 1 mole of [tex]PCl_3[/tex] reacts with 1 mole of [tex]Cl_2[/tex] to give 1 mole of [tex]PCl_5[/tex].
From this we conclude that the mole ratio of [tex]PCl_3[/tex] to [tex]PCl_5[/tex] is 1 : 1.
Hence, the mole ratio of [tex]PCl_3[/tex] to [tex]PCl_5[/tex] is 1 : 1.
Answer:
A
Explanation:
Which Drug is used not to cure Cancer, but can kill Cancer?
(A) = Adrenaline.
(B) = Burger King.
(C) = Chemotherapy.
(D) = Deoxyribose.
(E) = Ethanol.
Answer:
chemotherapy
Explanation:
Please tell me the answers to A, B, and C
Answer:
A=element
B=compond
C=solution
When 28.0 g of acetylene reacts with hydrogen, 24.5 g of ethane is produced. What is the percent yield of C2H6 for the reaction?
C2H2(g) + 2H2(g) → C2H6(g)
Answer:
[tex]Y=75.6\%[/tex]
Explanation:
Hello.
In this case, since no information about the reacting hydrogen is given, we can assume that it completely react with the 28.0 g of acetylene to yield ethane. In such a way, via the 1:1 mole ratio between acetylene (molar mass = 26 g/mol) and ethane (molar mass = 30 g/mol), we compute the yielded grams, or the theoretical yield of ethane as shown below:
[tex]m_{C_2H_6}^{theoretical}=28.0gC_2H_2*\frac{1molC_2H_2}{26gC_2H_2}*\frac{1molC_2H_6}{1molC_2H_2} *\frac{30gC_2H_6}{1molC_2H_6}\\ \\m_{C_2H_6}^{theoretical}=32.3gC_2H_6[/tex]
Hence, by knowing that the percent yield is computed via the actual yield (24.5 g) over the theoretical yield, we obtain:
[tex]Y=\frac{24.5g}{32.3g}*100\%\\ \\Y=75.6\%[/tex]
Best regards.
What is the atomic number of arsenic (As)?
O A. 33
O B. 15
C. 75
D. 4
SUB
Answer:
33
Explanation:
) Do you think the pH of 1,0 M tri-methyl ammonium (CH3)3NH+, pKa = 9.80, will be higher or lower than that of 1.0 M phenol, C6H5OH? What is the difference in pH values for the two acids?
Answer:
1. The pH of 1.0 M trimethyl ammonium (pH = 1.01) is lower than the pH of 0.1 M phenol (5.00).
2. The difference in pH values is 4.95.
Explanation:
1. The pH of a compound can be found using the following equation:
[tex] pH = -log([H_{3}O^{+}]) [/tex]
First, we need to find [H₃O⁺] for trimethyl ammonium and for phenol.
Trimethyl ammonium:
We can calculate [H₃O⁺] using the Ka as follows:
(CH₃)₃NH⁺ + H₂O → (CH₃)₃N + H₃O⁺
1.0 - x x x
[tex]Ka = \frac{[(CH_{3})_{3}N][H_{3}O^{+}]}{[(CH_{3})_{3}NH^{+}]}[/tex]
[tex] 10^{-pKa} = \frac{x*x}{1.0 - x} [/tex]
[tex] 10^{-9.80}(1.0 - x) - x^{2} = 0 [/tex]
By solving the above equation for x we have:
x = 0.097 = [H₃O⁺]
[tex] pH = -log([H_{3}O^{+}]) = -log(0.097) = 1.01 [/tex]
Phenol:
C₆H₅OH + H₂O → C₆H₅O⁻ + H₃O⁺
1.0 - x x x
[tex]Ka = \frac{[C_{6}H_{5}O^{-}][H_{3}O^{+}]}{[C_{6}H_{5}OH]}[/tex]
[tex] 10^{-10} = \frac{x^{2}}{1.0 - x} [/tex]
[tex] 1.0 \cdot 10^{-10}(1.0 - x) - x^{2} = 0 [/tex]
Solving the above equation for x we have:
x = 9.96x10⁻⁶ = [H₃O⁺]
[tex] pH = -log([H_{3}O^{+}]) = -log(9.99 \cdot 10^{-6}) = 5.00 [/tex]
Hence, the pH of 1.0 M trimethyl ammonium is lower than the pH of 0.1 M phenol.
2. The difference in pH values for the two acids is:
[tex] \Delta pH = pH_{C_{6}H_{5}OH} - pH_{(CH_{3})_{3}NH^{+}} = 5.00 - 1.01 = 4.95 [/tex]
Therefore, the difference in pH values is 4.95.
I hope it helps you!
Particle motion in ice is __________than partlice motion in water.
1. faster
2. slower
3. the same
Answer:
1. Faster
Explanation:
Define waves in your own words.
Answer:
Waves is the disturbance or variation that transfer energy from one location to other
Answer:
this is not in my words but i think this will help
(put some of the words you would use in this)
Explanation:
Transverse waves are always characterized by particle motion being perpendicular to wave motion. A longitudinal wave is a wave in which particles of the medium move in a direction parallel to the direction that the wave moves. ... Longitudinal waves are always characterized by particle motion being parallel to wave motion.
hope i helped
informative essay on bohrs Thomson's and rutherford model of the atom
Help plzzzzzzzzzzzzzzz
Answer:
um wheres thepassage?
Explanation:
There are approximately 250 million passenger vehicles in the United States. If each is driven 25,000 km per year, calculate the total mass of CO, NOx and HC emitted in 1970 if all vehicles just meet the government standard at that time. Please find the standard values in textbook. (Please round up to 3 decimal points and use 'E' for exponent)
Answer:
CO = 1.320 x 10¹¹ Kg
NOx = 1.942 x 10¹⁰ Kg
HC = 1.592 x 10¹⁰ Kg
Explanation:
Given that;
there are approximately 250 million passenger vehicles
each is driven 25,000 km per year which is 15534.28 miles per year
In 1970, the vehicular emission norms are;
CO = 34 g/mile , NOx = 5 g/mile , HC = 4.1 g/mile
so emission of CO in 1970 is;
250000000 × 15534.28 × 34 g
= 1.320 x 10¹⁴ g
= 1.320 x 10¹¹ Kg
Also, emission of NOx in 1970
250000000 × 15534.28 × 5 g
= 1.9417 x 10¹³ g
= 1.942 x 10¹⁰ Kg
emission of HC in 1970
= 250000000 × 15534.28 × 4.1 g
= 1.5922 x 10¹³ g
= 1.592 x 10¹⁰ Kg
Which element contains four electrons in its third and outer main energy level?
Answer:
valence electrons
Explanation:
The valence electrons are the outer most electrons and the principal energy level in which they belong will vary for .
The chemical element which contains four (4) electrons in its third and outer main energy level is: Silicon (Si).
An electron shell can be defined as the outermost shell of an atom of a chemical element around the atomic nucleus.
Hence, an electron shell is an orbital that is typically accompanied by electrons around the nucleus of an atom.
A sublevel is also referred to as an orbital and it can be defined as an energy level that is associated with the electrons found outside the atomic nucleus.
In Chemistry, there are four main (4) types of sublevel and these are:
s orbital (sublevel): it has one (1) orbital i.e 1s.p orbital (sublevel): it has three (3) orbitals.d orbital (sublevel): it has five (5) orbitals.f orbital (sublevel): it has seven (7) orbitals.In the third (3rd) energy level, there are only three (3) sublevels and these are; s, p and d sublevels.
Silicon is a chemical element that is found in group (4) of the periodic table because it has four (4) electrons in its third and outermost shell.
In its ground state, Silicon (Si) contains the following number of electrons:
Two electrons in its first (n = 1) energy level. Eight electrons in the second (n = 2) energy level.Lastly, it contains four (4) electrons in its third (n = 3) and outer main energy level.Read more: https://brainly.com/question/18214726
ILL GIVE BRAINLIEST IF CORRECT!!! students who enjoy acting out plays likely think with what part of their brains?
A. Back Brain
B. Front Brain
C. Left Brain
D. Right Brain
Answer:
B
Explanation:
The front brain(cerebrum) is the part of the brain that controls important cognitive skills in humans, such as emotional expression, problem solving, memory, language, judgment, and sexual behaviors.
Here the students who enjoy acting out plays likely think with front brain. I guess so..
Answer: The front brain(cerebrum) is the part of the brain that controls important cognitive skills in humans, such as emotional expression, problem solving, memory, language, judgment, and sexual behaviors
Explanation: people who do acting or choir would use the front brain..... i think :) hope this helps.
A 13.0-L scuba diving tank contains a helium-oxygen (heliox) mixture made up of 23.6 g of He and 4.85 g of O2 at 298 K. Calculate the mole fraction of each component in the mixture.
Answer:
[tex]x_{He}=0.975\\x_{O_2}=0.025[/tex]
Explanation:
Hello.
In this case, since we know the mass of both helium and oxygen, in order to obtain the mole fractions we first need the compute the moles by using their atomic masses, 4.00 g/mol and 32.00 g/mol respectively as shown below:
[tex]n_{He}=23.6gHe*\frac{1molHe}{4.00gHe}=5.90molHe\\ \\n_{O_2}=4.85gO_2*\frac{1molO_2}{32.00gO_2}=0.152molO_2\\[/tex]
Therefore, the mole fractions are:
[tex]x_{He}=\frac{n_{He}}{n_{He}+n_{O_2}}=\frac{5.90}{5.90+0.152} \\\\x_{He}=0.975\\\\x_{O_2}=\frac{n_{O_2}}{n_{He}+n_{O_2}} =\frac{0.152}{5.90+0.152} \\\\x_{O_2}=0.025[/tex]
Best regards!
Help :( the blue boxes are clickable
Answer:
I am sure they are why won't they
List the steps in the water cycle, in the correct order?
Determine the mass (in grams) of NaCl in 294 grams of a 24.1% (m/m) NaCl solution. Be sure to report to the correct number of significant figures with no units.
I NEED HELP WITH THIS URGENTLY!!!!!
Answer:
70.9 grams 3 sig figs
Explanation:
24.1% of 294 grams = 0.241(294 gram) = 70.854 grams ≅ 70.9 grams 3 sig figs
A sample of an unknown gas weighs 0.419 grams and produced 5.00L of gas at 1.00atm (unknown gas only) and 298.15K, what is the molar mass (g/mole) of this unknown gas
Answer:
molar mass of unknown gas = 1.987 g/mol
Explanation:
First, the number of moles of the unknown gas is found
Using the ideal gas equation: PV = nRT
P = 1.00 atm, V = 5.00 L, T = 298.15 K, R = 0.082 L.atm.mol⁻¹K⁻¹
n = PV/RT
n = (1.00 atm * 5.00 L)/(298.15 K *0.082 L.atm.mol⁻¹K⁻¹)
n = 0.2109 moles
Molar mass = mass/ number of moles
molar mass = 0.419 g/ 0.2109 mols
molar mass of unknown gas = 1.987 g/mol
The molar mass of unknown gas by using ideal gas equation = 1.987 g/mol.
Ideal gas equationThis equation gives the relation between pressure, volume, temperature as given below:
[tex]PV = nRT[/tex]
P = 1.00 atm, V = 5.00 L, T = 298.15 K, R = 0.082 L.atm.mol⁻¹K⁻¹
Substitute the above values in the above equation as follows:
n = (1.00 atm * 5.00 L)/(298.15 K *0.082 L.atm.mol⁻¹K⁻¹)
n = 0.2109 moles
Formula for molar mass[tex]Molar mass = mass/ number of moles[/tex]
Calculate molar mass by using the above equation,
molar mass = 0.419 g/ 0.2109 moles
The molar mass of unknown gas = 1.987 g/mol
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Which is NOT an example of plants demonstrating the characteristics of life?
A. Plants are forces to make adaptations depending on its environment
B. A plant has stimuli that cause it to grow towards the sun
C. There are stages of growth that plants go through depending on favorable conditions
D. The leaves on a plant move in reaction to the wind
Answer:
D
Explanation:
trust me bro ive done this
Option D does not represent an example of plants demonstrating the characteristics of life.
The following information should be considered:
Plants to be treated as the forces for making the adaptions and based on the environment. The plant contains stimuli that result to grow towards the sun. There should be the growth stages based on the favorable conditions.Therefore we can conclude that Option D does not represent an example of plants demonstrating the characteristics of life.
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Condensation occurs with the removal of thermal energy.
True or False? If false, rewrite to make the question true.
PLZZZ HELP
Answer:
true
Explanation:
Condensation is the opposite of vaporization. True. When does condensation occurs, does a gas lose or gain thermal energy?
Answer:
True
Explanation:
Condensation is formed with moisture and cold air, so the removal of thermal energy, or heat, would create the perfect conditions :)
The indicator dilution method is a technique used to determine flow rates of fluids in channels for which devices like rotameters and orifice meters cannot be used (e.g., rivers, blood vessels, and large- diameter pipelines). A stream of an easily measured substance (the tracer) is injected into the channel at a known rate and the tracer concentration is measured at a point far enough downstream of the injection point for the tracer to be completely mixed with the flowing fluid. The larger the flow rate of the fluid, the lower the tracer concentration at the measurement point. A gas stream that contains 1.50 mole% CO2 flows through a pipeline, Twenty (20.0) kilograms of CO2 per minute is injected into the line. A sample of the gas is drawn from a point in the line 150 meters downstream of the injection point and found to contain 2.3 mole% CO2.(a) Estimate the gas flow rate (k mol/min) upstream of the injection point.(b) Eighteen seconds elapses from the instant the additional CO2 is first injected to the time the CO2 concentration at the measurement point begins to rise. Assuming that the tracer travels at the average velocity of the gas in the pipeline (i.e., neglecting diffusion of CO2), estimate the average velocity (m/s), if the molar gas density is 0.123k mol/m3 what is the pipe diameter?
Answer:
[a]. 55.5kmol/min.
[b]. The average velocity = 8.3m/s.
pipe diameter = 1.0954m.
Explanation:
So, from the question above we are given the following data or information or parameters which are going to help us in solving the above question;
=> ''A gas stream that contains 1.50 mole% CO2 flows through a pipeline''
=> ''Twenty (20.0) kilograms of CO2 per minute is injected into the line.''
=> '' . A sample of the gas is drawn from a point in the line 150 meters downstream of the injection point and found to contain 2.3 mole% CO2''
=> ''molar gas density is 0.123k mol/m3''
[a].The gas flow rate (k mol/min) upstream of the injection point can be calculated as follows.
- Determine the mass balance= j₁ +[ 20 /.123 × 44] = j₃. Thus, the flow gas rate is given as;
w₁ × 1.50 mole% CO2 + 3.6954= 2.3 mole% CO2 × w₃.
-3.610 = - 0.008w₁.
w₁ = 451.3 m³/min.
Thus, the flow rate = 0.123 × 451.3 = 55.51 kmol/min.
[b]. The average velocity = 150/ 18 seconds = 8.3 m/s.
[c]. Pipe Diameter can be calculated as follows;
0.123 × 8.3 × [3.12 × (pipe diameter)² / 4] = 55.51/60.
[1.0209 × 3.12]/4 × [pipe diameter]² = 0.9252.
0.8014065 × [pipe diameter]² = 0.9252.
[pipe diameter]² = 0.9252/ .8014065.
[pipe diameter]² = 1.15443.
[pipe diameter] = √1.15443.
[pipe diameter] = 1.2 m² = 1.0954m.
A) The gas flow rate (k.mol/min) upstream of the injection point is;
55.51 k.mol/min
B) The average velocity and the diameter of the pipe are respectively;
8.33 m/s and 1.072 m
Gas Flow rate in thermodynamics
Due to the fact that there is no reaction or accumulation in the pipeline, we can say that the input of CO₂ is equal to it's output. Thus;
Upstream + Injection = Downstream
A) If we assume that x is the flow rate of gas (kmol/min), then there is the we can write the balance as:
0.015x + (20/44) = 0.023(x + 20/44)
Expanding gives us;
0.015x + 0.4545 = 0.023x + 0.01045
Solving for x gives;
x = 55.51 kmol/min
B) Formula for velocity is;
v = distance/time
Thus, since the length of the pipe is 150 m/s and time is 18 seconds, then velocity is;
v = 150/18
v = 8.33 m/s
Now, volumetric flow rate is calculated from;
Q = q' * ρ
where;
q' is gas flow rate
ρ is gas density
Thus;
Q = 55.51 * 0.123
Q = 451.3 m³/min = 7.522 m³/s
We can also express average velocity as;
v = Q/A
where A is area = πD²/4
Thus;
8.33 = 7.522/(πD²/4)
Making D the subject of the formula gives;
D = √((4 * 7.522)/(8.33π))
D = 1.072 m
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Which of the following best support the function of electrical signals in the nervous system?
Each nerve cell is connected to the brain by electrical signals.
Nerve cells communicate with the brain by sending out electrical signals
Electrical signals keep nerve cells alive.
Electrical signals are used to get rid of waste produced in the nervous system.
Answer:
Each nerve cell is connected to the brain by electrical signals
Explanation:
Answer:
they said it above me
Explanation:
What do you learned about homogeneous mixture?
Answer:
homogeneous is consisting a part of or people are similar to each other or are if same type.
A substance that is dissolved in a solution is called a(n) __________________.
solute
compound
ion
Answer:
solute
Explanation:
When an aqueous sodium hydroxide solution of sodium benzoate is acidified, what precipitate is formed, and why does it precipitate?
Answer:
Insoluble benzoic acid is formed
Explanation:
When benzoic acid is dissolved in sodium hydroxide solution, sodium benzoate is formed. This compound is highly soluble in the aqueous layer.
If this solution is now acidified, the equilibrum position shifts towards the undissociated benzoic acid and a precipitate appears.
An insoluble substance formed during crystallization or precipitation is called a precipitate. The precipitate of the reaction formed is of benzoic acid.
What is a precipitation reaction?A precipitation reaction is a type of reaction in which an insoluble salt or substance is formed as the result of the reaction between the soluble salt solutions.
The substance or the salt produced that does not get dissolved in the solution is called a precipitate.
In the reaction, benzoic acid reacts with the sodium hydroxide salt and forms sodium benzoate salt as shown,
[tex]\rm C_{6}H_{5}COOH(s) + NaOH(aq) \rightarrow C_{6}H_{5}COO^{-}Na^{+}(aq) + H_{2}O(l)[/tex]
When the salt of sodium benzoate is acidified then the precipitation of benzoic acid is formed. The precipitate occurs because the equilibrium shifts towards the undissociated benzoic acid.
Therefore, a precipitate of benzoic acid is formed.
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PLSSS HELP Match each image to the
correct step of meiosis. PLS HELP
Answer:
Explanation:
Here you go!! Hope this helps.
I need help pls... look at photo
Answer:
LA PRIMERA ES N
Explanation:
A chemist decomposes samples of several compounds; the masses of their constituent elements are listed. Calculate the empirical formula for each compound.
a. 1.245 g Ni, 5.381 g I,
b. 2.677 g Ba, 3.115 g Br,
c. 2.128 g Be, 7.557 g S, 15.107 g
Answer:
you can see the empirical formula at the pic
The empirical formula for compound (a) is NiI2, (b) is BaBr2 and (c) is BeS.
What is empirical formula?
Empirical formula of a compound is defined as the simplest whole number ratio of atoms present in a compound.
(a) 1.245 g Ni : 5.381 g I
Mole of Ni ; Mole of I = 1.245/59 : 5.381/127 = 0.02 : 0.04 = 1:2
So the formula is NiI2
(b) 2.677 g Ba : 3.115 g Br
Mole of Ba : Mole of Br = 2.677/137 : 3.115/60 = 0.019 : 0.038
= 0.02 : 0.04 = 1:2
So the formula is BaBr2
(c) 2.128 g Be : 7.557 g S
Mole of Be : Mole of S = 2.128/9 : 7.557/32 = 0.2 : 0.2 = 1:1
So the formula is BeS
Thus, empirical formula for compound (a) is NiI2, (b) is BaBr2 and (c) is BeS.
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True or false: BrF5(aq) is a good insulator.
Answer:
true
hope this helps :)
Explanation:
True, [tex]BrF_5[/tex] (aq) is a good insulator.
What is an insulator?A material or an object that does not easily allow heat, electricity, light, or sound to pass through it.
Bromine pentafluoride appears as a colourless, fuming liquid with a pungent odour. Used to make other chemicals and in rockets.
Hence, [tex]BrF_5[/tex] (aq) is a good insulator.
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