Given the remaining quantity after the given time and the half-life, the initial quantity or original mass of the sample is 32g.
Option A) is the correct answer.
What was the mass of the original sample?Half-life is simply the amount of time it takes a given quantity to decrease to half of its initial value.
Using the expression:
[tex]N_{(t)} = N_{0}\frac{1}{2}^{\frac{t}{t_{\frac{1}{2} }} }[/tex]
Given the data in the question;
Remaining quantity Nt = 1.0gtime t = 40 daysHalf life t(1/2) = 8.07 days[tex]N_{(t)} = N_{0}\frac{1}{2}^{\frac{t}{t_{\frac{1}{2} }} }[/tex]
[tex]1.0g = N_{0} * (0.5)^{40days/8.07days}\\\\1.0g = N_{0} * (0.5)^{4.95662949}\\\\1.0g = N_{0} * 0.0322037055\\\\N_{0} = \frac{1.0g}{0.0322037055} \\\\N_{0} = 31.05g = 32g[/tex]
Therefore, given the remaining quantity after the given time and the half-life, the initial quantity or original mass of the sample is 32g.
Option A) is the correct answer.
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Which formula represents a hydrocarbon?
A. CaO2
B.C5H12
C.CH2O
D.H2SO4
Answer:
B.C5H12 that is pentane
Explanation:
hydrocarbon has only hydrogen and carbon atoms
Calculation: If a compound is 14.40% hydrogen by mass and 85.60% carbon by mass, what is the empirical formula?
Group of answer choices
Answer:
CH2
Explanation:
We are given that a compound is 14.40% hydrogen and 85.60% carbon.
Let the mass of the substance be 100g.
Mass of the hydrogen: 14.40% of 100 = 14.40 g
Mass of the carbon: 85.60% of 100 = 85.60 g
Now, let's find the moles of hydrogen:
[tex]14.40 g*\frac{1 mole}{1gH} = 14.40 mole[/tex]
Moles of carbon:
[tex]85.60g*\frac{1 mol}{12gC} = 7.13mol[/tex]
Let's put these in a ratio and simplify:
7.13 mole C: 14.40 mole H
1 mole C: 2 mole H
Therefore, the empirical formula of this compound is CH2.
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In a single displacement recation of magnesium + copper sulfate. What reactant loses electrons and why?
Indicate how the gas molecules move between the system and the surroundings based on changes in pressure, temperature, and volume and the number of moles.
The gas molecules move between the system and the surroundings follow PV=nRT.
What are molecules?The smallest particle of a substance has all of the physical and chemical properties of that substance.
An increase in pressure pushes the molecules closer together, reducing the volume. If the pressure is decreased, the gases are free to move about in a larger volume.
In the kinetic theory of gasses, increasing the temperature of a gas increases in average kinetic energy of the molecules, causing increased motion.
The reduction in the volume of the gas means that the molecules are striking the walls more often increasing the pressure, and conversely if the volume increases the distance the molecules must travel to strike the walls increases and they hit the walls less often thus decreasing the pressure.
At constant temperature and pressure the volume of a gas is directly proportional to the number of moles of gas. At constant temperature and volume the pressure of a gas is directly proportional to the number of moles of gas.
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Blank? mammals are the largest group of mammals.
Answer:
Blank = rodent(s)
Explanation:
Rodents are by far the largest group of mammals.
Compare how entropy changes for the following two systems:
System A: Two gases mix when the valve separating two containers is opened.
System B: A solid powder decomposes to form a solid product and a gas product.
The measure of the randomness of the system is the change in the entropy. The mixing of two gases and decomposition of the solid will increase the entropy.
What is entropy?Entropy is the disorderliness and the randomness of the system when the thermal energy is not present in a sufficient amount to initiate the reaction. In system A, when two gases are mixed then the entropy increases as the number of gaseous molecules increases.
In system B, when a solid powder gets decomposed to form a solid product and a gaseous product the entropy increases as along the solid particles the gas is also produced.
Therefore, in both the systems the entropy increases.
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Caco3(s) ----> cao(s) + co2 (g)
this reaction is not spontaneous at room temperature. what is the sign of ah for this reaction? explain how you arrived at your answer
Since the reaction is not spontaneous at room temperature, the ΔH will be positive.
What are spontaneous reactions?They are reactions that require no additional effort in order for them to take place under certain conditions.
For spontaneous reactions, the change in the energy of the system, otherwise known as ΔH, is always negative. On the other hand, reactions with positive ΔH are non-spontaneous.
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Can someone please help????nThis is sooooo hard
Answer:
See explanation.
Explanation:
I highly suggest you watch OChem Tutor's videos on IUPAC nomenclature because the actual naming would take a lot of time to teach in text-based format. But here is how to name them:
1) I think there are two seperate pictures for number 1. The molecule on the left is 1-pentene and the one on the right is 4-methyl-1-pentene. If the whole thing is one molecule but there is just a bond missing where the red marker numbers are, that molecule would be 9-methyl-1,6-decadiene.
2) 4-methyl-2-pentene
3) 2,4-octadiene
4) 1,5-nonadiene
5) 2,5-dimethyl-3-hexene
6) 3,6-dimethyl-2,4-heptadiene
7) 2,5,5-trimethyl-2-hexene
Calculate the molarity of a sodium hydroxide solution if 50.0 mL of this solution was completely neutralized by 46.6 mL of 0.750 M sulfuric acid.
Answer: 0.699 M
Explanation:
[tex]M_{A}V_{A}=M_{B}V_{B}\\(0.750)(46.6)=M_{B}(50.0)\\M_{B}=\frac{0.750)(46.6)}{50.0}=\boxed{0.699 \text{ M}}[/tex]
In a certain reaction at stp, 29.2 l of methane is combusted
with 63.3 l of oxygen.
what volume of excess reactant remains after the reaction is
complete?
The volume of excess oxygen will 2.28 L
Stoichiometric calculationFrom the equation of the reaction:
[tex]CH_4(g) + 2O_2(g) --- > CO_2(g) + 2H_2O(g)[/tex]
The mole ratio of the two reactants is 1:2.
1 mole of gas at STP = 22.4 L
Mole of 29.2 L of methane at STP = 29.2/22.4 = 1.3 moles
Mole of 63.3 L of oxygen at STP = 63.3/22.4 = 2.8 moles.
Thus, oxygen is in excess because 1.3 x 2 = 2.6 moles is needed to react with 1.3 moles methane.
Excess mole of oxygen = 2.8 - 2.6 = 0.2 moles
Volume of 0.2 moles at STP = 22.4 x 0.2 = 2.28 L
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A student put a bottle of water and a can of sugared soda in the freezer to chill them quickly. when she took them out, the bottle of water was frozen but the can of soda was not. explain why this happened.
The soda water didn't freeze because of the depression in freezing point as compared to the water.
What is Freezing Point Depression ?When a solute is added to a pure solvent , then the value of freezing point is reduced.
The decrease in the freezing point is directly proportional to the molality of the solute.
It is given in the question that
A student put a bottle of water and a can of sugared soda in the freezer to chill them quickly.
when she took them out, the bottle of water was frozen but the can of soda was not.
It is because water is the pure solvent , so freezing point is fixed but the soda water has sugar and Carbon Di oxide along with the solvent water , the presence of the sugar and Carbon -di-oxide decreases the freezing point of the soda water and so it doesn't freezes.
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What is the total number of protons and electrons in one mole of hydrogen gas?
what is the molarity of 28.9g of calcium chloride dissolved in water to make 0.78L of solution
Answer:
.334 M
Explanation:
Ca Cl2 is calcium chloride
Ca = 40.078 gm/mole
Cl = 35.45 gm/ mole
40 . 078 + 2 * 35.45 = 110.978 gm/mole for Ca Cl2
28.9 gm / 110.978 gm/mole = .260 moles CaCl2
.260 moles/ .78 liter = .334 M
A small, positively charged ball is moved close to a large, positively charged ball. Which describes how the small ball likely responds when it is released?
Answer:
It is repelled ( pushed away from the larger ball)
Explanation:
Like charges repel.
Opposites attract.
Determine the rate of a reaction that follows the rate law: rate = k[A]m[B]n, where:
k=1.5
[A]=1M
[B]=3m
m=2
n=1
A. 4.5 (mol/L)/s
B. 1.5 (mol/L)/s
C. 13.5 (mol/L)/s
D. 9.0 (mol/L)/s
The rate of a reaction that follows the rate law: rate = k[A]m[B]n, is A. 4.5 (mol/L)/s.
What is the rate of reaction?The rate of reaction is the speed by which the reactions happening.
The given values are k=1.5.
[A]=1M
[B]=3m
m=2
n=1
The formula is v = k[A] ˣ [B] y
v = 1.5 x 1 ² x 3¹ = 4.5 (mol/L)/s
Thus, the correct option is A. 4.5 (mol/L)/s.
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1. On a train ride cross-country, the trees, buildings, and people appear to be speeding by the window. This is because the train is our _____
2. Scientists use the ______
system for making measurements.
3. Physical science studies the relationships between ____,____,
and ______.
4. If 6.6 tyrannosaurs weigh 30,000 kg, then what does one tyrannosaur weigh?
5. For most activities, the ___
makes a handy frame of reference.
On a train ride cross-country, the trees, buildings, and people appear to be speeding by the window. This is because the train is moving in the forward direction.
Scientists use the shared system for making measurements. This system is also called system of international.
Physical science studies the relationships between natural but non-living objects. Physical science is ordinarily thought of as consisting of four broad areas: astronomy, physics, chemistry, and the Earth sciences.
If 6.6 tyrannosaurs weigh 30,000 kg, then one tyrannosaur weigh about 4545 kg. For most activities, the earth makes a handy frame of reference.
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CORRWCT ANSWER GETS BRAINLIST
Answer:
Parts per million - Option B
Explanation:
Is it possible to explain this ?
Hope this helped and have a good day
Answer: b parts per million
Explanation:
elect all statements that correctly describe the stability of eclipsed and staggered conformers. Multiple select question. Staggered conformers are lower in energy than eclipsed conformers. Electron-electron repulsion between bonds in an eclipsed conformer may contribute to the low energy of this conformer. Staggered conformers possess torsional strain. Eclipsed conformers possess torsional strain.
Staggered conformers are lower in energy than eclipsed conformers , Option A is the right answer.
What are Eclipsed and Staggered Confirmation ?The arrangement of atoms in molecule such that the dihedral angle formed is 60 degree is called Staggered Conformation and the arrangement of atoms in which the dihedral angle is 0 degree is called Eclipsed Confirmation
Among the given statements
The statement that best describe the stability of Staggered Conformers and eclipsed conformers is Staggered conformers are lower in energy than eclipsed conformers .
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How many moles are 3.20 x102 formula units of calcium iodide?
The number of moles in 3.20 x 10² formula units of calcium iodide is 0.053 moles.
How to calculate number of moles?The number of moles in the formula units of a substance is calculated by dividing the formula unit by Avogadro's number.
According to this question, 3.20 x 10² formula units are in calcium iodide. The number of moles is as follows:
no of moles = 3.20 x 10²² ÷ 6.02 × 10²³
no of moles = 0.53 × 10-¹
no of moles = 0.053 moles
Therefore, the number of moles in 3.20 x 10² formula units of calcium iodide is 0.053 moles.
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Which of the following statements holds true for a chemical change?
A.
In a chemical change, no new substance is formed.
B.
In a chemical change, a substance changes its phase.
C.
In a chemical change, the molecular structure of a substance changes.
D.
In a chemical change, one substance dissolves into another.
Use the drop-down menus to identify each organic reaction as an addition, substitution, elimination, or condensation reaction. (C H 3) subscript 3 C O H plus C H 3 O H right arrow (C H 3) subscript 3 C O C H 3 plus H 2 O. H 3 C H C double bond C H C H 3 plus H upper B r right arrow C H 3 C H 2 C H (upper B r) C H 3. (C H 3) subscript 3 C O H right arrow C H 3 C H 3 C H 2 plus H 2 O. A benzene ring plus upper B r subscript 2 right arrow benzene ring with upper B r bonded to the top, plus upper H upper B r.
A chemical reaction involves an interaction between two or more species to yield a product.
What is a chemical reaction?A chemical reaction involves an interaction between two or more species to yield a product.
The following is the classification of the reactions based on type;
The first reaction shown in the attachment is a condensation reactionThe second reaction is an addition reactionThe third reaction is an elimination reactionThe fourth reaction is a substitution reactionLearn more about reaction:https://brainly.com/question/9524025
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The descriptions below explain two ways that water is used by plants on a sunny day.
I. In a process called transpiration, some liquid water in leaves changes to water vapor. The water vapor is released into the air through tiny pores in the leaves. This allows more liquid water from the soil to be pulled up the roots and stem to replace water lost from the leaves.
II. Plants use some of this water in leaves in a process called photosynthesis. During photosynthesis, water and carbon dioxide break apart and recombine to form two new substances, oxygen and glucose.
In a sunny day, the plant makes use of water through photosynthesis and transpiration.
What is photosynthesis?Photosynthesis is defined as the process by which green plants, which has chlorophyll, makes use of water and carbondioxide in the presence of sunlight as energy to form oxygen and glucose.
Transpiration is the movement is of water out of the plant through its pores located on the leaves, roots and stem. This process is increased in sunny seasons.
Therefore, In a sunny day, the plant makes use of water through photosynthesis and transpiration.
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Answer:
in transpiration, because some of its properties change, water undergoes a physical change but keeps its identity. In photosynthesis, because its identity changes, water undergoes a chemical change.
Explanation:
How can you determine whether a solution is acidic or basic?
Answer:
Look at the pH level.
Explanation:
The best way to determine whether a solution is acidic or basic is to look at its pH level. The pH of a solution is a number between 0 and 14.
If a solution has a pH of less than 7, then it is acidic.
If a solution has a pH of 7, then it is neutral.
If a solution has a pH of greater than 7, then it is basic.
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72. how is it possible to recognize the end point of a titration?
Which statement
about
gravitational force is most
accurate?
Gravitational force is the force of attraction. This kind of force forms an action-reaction in a situation.
What is gravitational force?Gravitational force is the force present that is directly proportional to the masses and inversely to the square of the distance present from the center of the masses.
It is independent of the medium and remains constant in any matter whether it is water, air, or soil. It is conservative and is a central force that obeys Newton's law of motions.
Therefore, the gravitational force follows the action and reaction.
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Can someone please help? This is super hard!!
Answer:
what is super hard?
Explanation:
what?
Hemoglobin ___________. (Select all that apply).
returns carbon dioxide to your lungs to be exhaled
carries oxygen from your lungs to every cell in the body
is the most complex protein in your body
is not made up of amino acids
Answer:
Option B and A
Explanation:
First our lungs take purified oxygen from air then provide it to heartOur heart gives oxygen to hemoglobin which is present in our bloodIt carries oxygen to all cellsand comes back with cO_2Which word equation shows hydrogen reacting with oxygen to form water?
oxygen + water → hydrogen
hydrogen + oxygen → water
oxygen + water hydrogen + water
→
Ohydrogen + water →→ oxygen
Answer:
calcule o PH e POH de 2,625g de HCLO em 2000cm3 (cl=35,5)
Explanation:
The word chemical equation which hydrogen reacting with oxygen to form water is hydrogen + oxygen → water.
What is chemical equation?Chemical equation is a symbolic representation of a chemical reaction which is written in the form of symbols and chemical formulas.The reactants are present on the left hand side while the products are present on the right hand side.
A plus sign is present between reactants and products if they are more than one in any case and an arrow is present pointing towards the product side which indicates the direction of the reaction .There are coefficients present next to the chemical symbols and formulas .
The first chemical equation was put forth by Jean Beguin in 1615.By making use of chemical equations the direction of reaction ,state of reactants and products can be stated. In the chemical equations even the temperature to be maintained and catalyst can be mentioned.
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A chemical reaction can be reversed if?
The energy of the products exceeds the activation energy threshold.
The energy of the reactants exceeds the activation energy threshold.
The energy of the products is less than the activation energy threshold.
The energy of the reactants is less than the activation energy threshold.
Chemical reaction can be reversed if the energy of the reactants is less than the activation energy threshold.
What is a reversible reaction?A reversible reaction is a reaction in which the conversion of reactants to products and the conversion of products to reactants occur simultaneously.
Conditions for reversible reactionIn equilibrium reaction, the activation energy of the forward reaction is more than that of backward reaction which causes bond breakage of the reactants.
Activation energy = (Threshold energy) - (Internal energy of the reactants)
Thus, a chemical reaction can be reversed if the energy of the reactants is less than the activation energy threshold.
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what is 24, 600μg into grams
Answer:
Your answer is 0.024Grams
Explanation:
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