How do an isotope and a radioactive isotope differ?
One light-hour is the distance that light travels in an hour. how far is this, in kilometers? ( recall that the speed of light is 300,000 km/s )
A radioactive substance decays exponentially. a scientist begins with 190 milligrams of a radioactive substance. after 17 hours, 95 mg of the substance remains. how many milligrams will remain after 21 hours
To calculate how many milligrams will remain after 21 hours, we can use the formula for exponential decay. We are given that after 17 hours, 95 mg of the substance remains. Solving for the remaining amount after 21 hours gives us approximately 88.66 mg.
Explanation:To calculate how many milligrams will remain after 21 hours, we can use the formula for exponential decay:
R = Ro * e^(-kt)
Where:
R is the remaining amount after time tRo is the initial amountk is the decay constantt is the time periodWe are given that after 17 hours, 95 mg of the substance remains. Plugging these values into the formula, we can solve for k:
95 = 190 * e^(-17k)
Simplifying, we get:
e^(-17k) = 1/2
Taking the natural logarithm (ln) of both sides:
-17k = ln(1/2)
Solving for k, we find k = ln(1/2) / -17.
Now, we can use this value of k to find the remaining amount after 21 hours:
R = 190 * e^(-kt)
R = 190 * e^(-(ln(1/2) / -17) * 21)
Calculating this expression will give us the remaining amount after 21 hours, which is approximately 88.66 mg.
What element has an electron configuration that ends in 2s2 2p4?
The oxygen element has an electronic configuration that ends with 2s²2p⁴.
What is an electronic configuration?The electron configuration can describe how electrons are arranged in different energy levels of an atom of an element. In the electron configuration of an atom, the number of electrons in a particular atomic orbital is written as a superscript. For example, the electron configuration of Helium (He) is written as 1s²2s².
The principal quantum number (n) will decide the maximum number of electrons that can be filled in a shell and is determined from the term 2n², where ‘n’ is the principal quantum number.
The atomic orbitals of an atom of a lower energy level should be completely filled before filling an atomic orbital with a higher energy level.
The atomic number of the oxygen atom is 8 and the electronic configuration is 1s²2s²2p⁴. It has six electrons in its valence shell and an electronic configuration ends with 2s²2p⁴.
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How could you turn a heterogeneous mixture of salt,sugar, and baking soda into a homogeneous mixture?
By dissolving all the mixture in water and mixing it thoroughly.
How do you shape a homogeneous mixture of sugar and salt?A homogeneous aggregate is a form of combination in which the composition is uniform and each part of the solution has the same properties. Salt, sugar, and many different materials dissolve in water to shape homogeneous combinations.
How do you make a heterogeneous mixture?A phase is any part of a pattern that has a uniform composition and properties. By definition, a pure substance or a homogeneous combination includes a single phase. A heterogeneous mixture consists of more phases. whilst oil and water are mixed, they do not blend lightly, however as an alternative form two separate layers.
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What information do the coefficients in a balanced chemical equation tell you
Explanation:
Coefficients are the number present in front of an atom or molecule in a chemical reaction.
For example, [tex]2Na + Cl_{2} \rightarrow 2NaCl[/tex]
In this reaction 2 in front of Na in reactant side shows 2 moles of sodium atoms are participating. Whereas 2 in front of NaCl in product side shows that 2 moles of sodium chloride is formed.
Therefore, we can conclude that coefficients in a balanced chemical equation tell you the moles of each substance involved in the reaction.
Lab worksheets oh what a tangled web we weave
Questions:
1. In how many food chains do the following animals appear? (count the # of food chains in part B)
hawk ___4__ earthworm ___2__ fox __6___
owl ___3__ snake __4___ small insects__1__
2. In how many food chains do plants (parts) appear? __all(14)__
3. List the names of the living things in this forest ecosystem that are producers. Plant parts
4. List those things that are only primary consumers. Crickets, earthworms, small insects, land snails, rabbits, and sparrows.
5. What is another name for an animal that is only a primary consumer? Herbivore
6. List those things that are only secondary consumers. Foxes, Hawks, Owls, Robins, Snakes.
7. What is another name for an animal that is only a secondary consumer? Carnivore
8. List the consumers that eat both plants and animals. Mouse, raccoon
9. What is another name for an animal that eats both plants and animals? Omnivore
10. What would happen to the food web if all the plants were removed? Everything will die. Explain your answer. Plants are the only organisms that can make their own food.
11. Describe how 3 animals might be affected if owls were removed from the food chain. Rabbits, mice, and snakes will probably increase since one of their predators is gone.
12. Draw three food chains showing producers and consumers that you might see in your backyard or on your way to school. (You may use words or drawings.)
grass → grasshopper → robin
nut → squirrel → cat
berry → bird → cat
(OR ANY OTHER VALID EXAMPLE)
13. Since only 10% of the energy produced by a level in a food chain is passed on to its predator, there have to be many more “prey” than “predators”. Draw a food pyramid of the first food chain listed in Part A. Remember that there are more producers than primary consumers, more primary consumers, and secondary consumers, etc.
raccoon
mouse
land snail
plant parts
14. If 2000 kcal of energy are available in the grass, how much energy would be available to the cow that eats the grass? To the human that eats the cow?
Assuming that all energy is used:
Since only 10% of the energy is available to the next level consumer – (.1)(2000 kcal) = 200 kcal of energy available to the cow. For the human (.1)(200 kcal) = 20 kcal available to the human. In other words, the human-only receives 1% of the original energy produced by the plant.
15. Which organism in this food web has the greatest influence on the ecosystem? Justify your answer.
This is a really tough one to answer. In reality, they are all equally important, and time should be spent going over all possibilities. Most students will guess plants since all life depends on the energy produced by plants. The teacher should also point out that, if a top-level consumer is killed off, the organisms it eats will increase in population, which might mean that more grass will be eaten, etc. All attempts should be made to show the interdependence of organisms in an ecosystem and to show that they are, therefore, all important.
Food web and Livings Things the Forest Eat graph
Which topic might interest a sociologist
suppose you want to do an experiment to hear how three different objects would sound when you dropping them the same distance. you drop a pebble a rock,and a grain of sand.what are the variables of your experiment
At standard pressure, during which physical change does the potential energy decrease?
Answer is: cooling.
Cooling is change from liquids to solids.
Another example is crystalisation, many elements and compounds form crystals.
A physical change occurs when a substance changes phase.
Physical property can be observed and measured without any changes in molecular composition. The same substance is present before and after the change.
The potential energy of a gas decreases during a phase change, such as cooling and condensing to a liquid.
Explanation:The potential energy of a gas decreases during a phase change when a large amount of energy is extracted from the system and causes a decrease in the gas's volume, pressure, or both. For example, when a gas is cooled and condenses to a liquid, its potential energy decreases. This is illustrated by a graph of pressure vs. temperature, where the pressure of a gas continually decreases as it is cooled at a constant volume.
Urine, at ph 6, contains __________ h+ as household bleach, at ph 13.
An automobile gasoline tank holds 21 kg of gasoline. when the gasoline burns, 84 kg of oxygen is consumed, and carbon dioxide and water are produced. what is the total combined mass of carbon dioxide and water that is produced?
This is as straightforward as it gets. If however you need to determine how much of each product is produced, then the balanced equation is a must.
Usually, gasoline is expressed as octane in combustion reactions, which means that the balanced equation for its combustion is
2C8H18+25O2→16CO2+18H2O
But, like I've said, for the combined mass of the products all you really need to know is the combined mass of the reactants.
Addendum
Let's say you want to know exactly how much of each compound is formed. In this case, you must check for a limiting reagent. The number of moles of octane is
21⋅103 g⋅1 mole octane114.0 g=184.2 moles
The number of moles of oxygen is
85⋅103 g⋅1 mole O232.0 g=2656 moles
According to the mole ratio between these two, each 2 moles of octane need 25 moles of oxygen, so
noxygen that reacts=noctane⋅252=2303 moles , which means that octane is the limiting reagent. The actual mass of oxygen that reacts is
2303 moles⋅32.0 g1 mole=73.7 kg
This means that the combined mass of the produced water and carbond dioxide is actually
21 kg+73.7 kg=94.7 kg
85 kg−73.7 kg=11.3 kg of oxygen will not react. If you want to count this oxygen as well, the total combined mass of the products will again be 106 kg .
In complete and ideal combustion of gasoline using the principle of conservation of mass, the total combined mass of carbon dioxide and water produced when a gasoline tank holding 21 kg of gasoline burns consuming 84 kg of oxygen is 105 kg.
Explanation:The subject of your question is based on the principle of conservation of mass, a fundamental concept in chemistry. The principle of conservation of mass states that the total mass of the reactants (the starting materials in a chemical reaction) is equal to the total mass of the products (the substances formed by the reaction). Hence, in the combustion (burning) of gasoline, the total combined mass of carbon dioxide and water that is produced would be equal to the sum of the masses of the gasoline and the oxygen consumed.
In your case, the total mass of gasoline and oxygen consumed is 21 kg (for gasoline) + 84 kg (for oxygen) = 105 kg. This means that given ideal condition and complete reaction, the total combined mass of carbon dioxide and water produced should be 105 kg.
Remember that this calculation assumes complete conversion of gasoline and oxygen into carbon dioxide and water, without production of other byproducts such as carbon monoxide and nitrogen oxides. Actual combustion processes may not be 100% efficient and may generate other byproducts.
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Mendeleev noticed that certain similarities in the chemical properties of elements appeared at regular intervals when teh elements were arranged in order of increasing
Mendeleev identified the periodic nature of elements' chemical properties when arranged by increasing atomic mass, leading to the creation of the periodic table.
Mendeleev noticed that certain similarities in the chemical properties of elements appeared at regular intervals when the elements were arranged in order of increasing atomic mass. This pattern is referred to as periodic, analogous to other phenomena that occur at regular intervals, such as the swing of a pendulum or the orbit of the moon around Earth. In the construction of his periodic table, Mendeleev even listed some elements out of atomic mass order so that they would be grouped with those that had similar chemical properties, such as tellurium (Te) being placed before iodine (I) based on properties rather than atomic mass.
Dimitri Mendeleev and Lothar Meyer independently recognized the periodic relationship among the elemental properties. While Meyer arranged elements by increasing atomic mass, Mendeleev's approach distinguished him by predicting undiscovered elements like gallium and germanium, which were later found and confirmed the utility of Mendeleev's table. This foresight helped solidify the significance of Mendeleev's work on the development of the periodic table.
What must be true about electrons sharing the same atomic orbital?
A. They must have absorbed different amounts of energy.
B.They must have opposite charges.
C. One is negatively charged, the other is neutral.
D. They must have opposite spins.
Answer:
D. They must have opposite spins.
Explanation:
Two electrons in the same atomic orbital have different spins or spin number. If one electron has +1/2 spin the other electron will have -1/2 spin. In other words if one electron is spinning in the clockwise direction the other electron will be spinning in the anticlockwise direction. Two electrons in the same atomic orbital have the same principal quantum number (n), azimuthal quantum number (l) and magnetic quantum number (m).
A catalyst increases the rate of a reaction by
A. providing an alternative reaction pathway with lower enthalpy change.
B. lowering the potential energy of the reactants in the reaction.
C. providing an alternative reaction pathway with lower activation energy.
D. lowering the potential energy of the products in the reaction.
Answer:
The correct option is C
Explanation:
For a reaction to occur, there is a minimum amount of energy that must be "met". This minimum amount of energy is called activation energy. Activation energy is the minimum amount of energy required for a reaction to occur. When this activation energy is high, it takes a longer time for the reaction to occur, hence it slows down the rate of a chemical reaction but when the activation energy is low, the rate of a chemical reaction is increased.
A catalyst is known to increase the rate of a chemical reaction - it does this by reducing the activation energy of the reaction, providing an alternative reaction pathway for the reaction.
What would happen to the pressure if the volume were reduced to 0.5 l and the temperature increased to 260 ∘c?
If volume is halved and temperature increased as per your question, the pressure would likely rise. Boyle's law suggests a pressure increase due to the volume reduction, and Charles's law predicts further pressure escalation with the temperature augmentation. However, the specifics of the final pressure would require more information on the gas's details.
Explanation:Your question asks what would happen to the pressure if the volume were reduced to 0.5 liters and the temperature were increased to 260 degrees Celsius. To answer, we can reference the ideal gas law and Charles's law, both concepts from physics.
Charles's law states that at constant pressure, the volume of a gas is directly proportional to its absolute temperature. However, your question involves changes in both volume and temperature, which requires application of the ideal gas law (PV = NkT). This equation suggests an inverse relationship between volume and pressure when the number of molecules (N) and temperature (T) are constant.
Per the question, the volume is halved and the temperature is increased, which complicates the pressure outcome. Boyle's law anticipates that halving the volume under constant temperature would double the pressure. If we consider the temperature increase, Charles's law would suggest that the enlarged thermal energy of the gas would further increase the pressure.
Finally, pressure is also contingent on the number of gas molecules. If the original density was halved without a loss of molecules, your volume would need to double, not halve. This inconsistency suggests the presence of additional influencing factors, perhaps a change in the gas's composition or quantity, or a misunderstanding in the question.
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N iron chloride compound contains 55.85 grams of iron and 106.5 grams of chlorine. what is the most likely empirical formula for this compound? fecl3 fe2cl fecl fe3cl fecl2
Which of the following compounds is a nonelectrolyte? A. sodium bromide B. magnesium sulfate C. carbon tetrachloride D. calcium hydroxide
Answer: Option (C) is the correct answer.
Explanation:
An electrolyte is defined as the substance which when dissolved in water dissociates into ions and it is able to conduct electricity.
Ionic compounds are the compounds which are soluble in water as ;like dissolves like.
Hence, water being a polar solvent is able to dissolve ionic compounds.
Sodium bromide and calcium hydroxide are ionic compounds. So, they act as an electrolyte as they dissociate into ions in water.
Whereas magnesium sulfate is also soluble in water as solubility of sulfates of group 2A decreases down the group.
On the other hand, [tex]CCl_{4}[/tex] is a non-polar compound. Hence, it will not dissociate into ions when dissolved in water.
Thus, we can conclude that carbon tetrachloride compound is a non-electrolyte.
Nonelectrolytes are compounds that, when dissolved in an aqueous solution, do not take on any particular ionic form. Solutions without electrolytes do not conduct electricity. Here carbon tetrachloride is a non-electrolyte. The correct option is C.
Chemical substances known as nonelectrolytes are those that do not ionize at all when placed in solution. Therefore, solutions devoid of electrolytes do not conduct electricity. Covalent bonds, as opposed to ionic ones, are typically used to hold together nonelectrolytes.
Sodium bromide and calcium hydroxide are ionic compounds. So, they act as an electrolyte as they dissociate into ions in water whereas magnesium sulfate is also soluble in water CCl₄ is a non-polar compound. Hence, it will not dissociate into ions when dissolved in water.
Thus the correct option is C.
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What is the error in the electron configuration, 1s2 2s2 2p6 3s2 3p5 4s2?
Final answer:
The error in the electron configuration 1s2 2s2 2p6 3s2 3p5 4s2 is that it places electrons in the 4s sublevel before filling the 3d sublevel. The correct order should fill the 3d sublevel before the 4s according to the Aufbau principle.
Explanation:
The student's question is about identifying the error in the given electron configuration, which is 1s2 2s2 2p6 3s2 3p5 4s2. The error in this configuration is the arrangement of electrons in the 4s sublevel before the 3d sublevel is filled. According to the Aufbau principle, which dictates the order in which sublevels are filled based on increasing energy, after the 3p sublevel is filled, electrons should start filling the 3d sublevel before the 4s. However, in the given configuration, it incorrectly shows two electrons in the 4s sublevel before the 3d sublevel has any electrons. The correct electron configuration after 3p6 should be 3d1 before moving to 4s1 or 4s2 depending on the element in question. For example, the correct configuration for potassium (Z=19) is 1s²2s²2p63s²3p64s¹, and for calcium (Z=20), it is 1s²2s²2p63s²3p64s².
“The maximum amount of energy that can be used to do work.” This statement describes which measure?
A.) Ecell
B.) K
C.) ∆G
D.) F
Scientists in ____ discover new products and processes and improve current technology.
Answer;
-Research and development
Scientists in research and development discover new products and processes and improve current technology.
Explanation;
Research scientists are responsible for designing, undertaking and analyzing information from controlled laboratory-based investigations, experiments and trials.
Additionally, research and development is an important means for achieving future growth and maintaining a relevant product in the market. Research may be basic research and applied research applied. Development is when findings of a research are utilized for the production of specific products including materials, systems and methods.
How much sulfur dioxide can be produced by the combustion of 21 tons of sulfur?
Consider a point 1 cm away from an electron with nothing else nearby. what expression could represent the electric potential at that location
An ionic bond is a bond between _____. a cation and an anion the ions of two different nonmetals valence electrons and cations the ions of two different metals
Answer: An ionic bond is a bond between a cation and an anion.
Explanation:
You can find the definition of ionic bond as the electrostatic force that bonds together the cations and anions in a ionic compound.
Cations are positively charged particles formed by the lack (loss) of electrons of the atoms.
Anions are negatively charged particles formed by the excess (gain) of electons of the atoms.
Therefore, being anions and cations particles with opposed charges, they will be attracted to each other by electrostatic force.
This electrostatic force that bonds together the cations and anions (particles with opposed charges) is named ionic bond.
The ionic bonds are typical of the cations formed by the metals, especially alkalyne metals (group 1 elements) and alkalyne earth metals (group 2 elements), with the anions formed by the non-metals, for instance oxygen (group 16) and halogens (group 17). The relative high difference in the electronegativities of these metals and non-metals permit that the metals transfer some few electrons to the non-metals, forming the respective cations and anions, which will result in the ionic bond between them.
Chromium is most commonly mined in the form of chromite, which has the chemical formula fecr2o4. calculate the percent by mass of each element in chromite, and give your answers to four significant digits.
The mass of each elements in chromite is as below
Fe =24.9 %
Cr =46.5%
O = 28.6%
calculation
percent mass = atomic mass of element / atomic mass of FeCr2O4 x 100
from periodic table the atomic mass for Fe = 55.85 g/mol,
Cr =52 g/mol since they are two atoms in FeCr2O4 = 2 x 52 = 104 g/mol
for O = 16 since they are two atoms in FeCr2O4 = 16 x4 = 64 g/mol
Atomic mass for FeCr2O4 is = 55.85 +104+ 64 = 223.85 g/mol
Percent mass for Fe =55.85 /223.85 x100 = 24.9 %
for Cr = 104 / 223.85 x 100 = 46.5%
For 0 = 64/223.85 x 100 = 28.6%
Why do non metallic elements pull electrons from metallic elements so effectively during a reaction?
The organization of hydrogen atoms around the double bond is called _____ when they are on the same side as the double bond, and _____ when they are on opposite sides of the double bond.
Describe the relative orientations of the orbitals related to an atom's 2p sublevel.
The 2p sublevel of an atom consists of three p orbitals, often denoted as [tex]\(2p_x\), \(2p_y\), and \(2p_z\)[/tex]. These p orbitals have specific relative orientations in space, which can be visualized as follows:
How to solve for the orbital1. [tex]\(2p_x\)[/tex]: This orbital has a dubbell-like shape oriented along the x-axis. The lobes of the du mbbell extend in opposite directions along the x-axis, and the orbital has zero electron density in the y and z directions. In other words, it is aligned parallel to the x-axis.
2. [tex]\(2p_y\)[/tex]: This orbital is similar in shape to [tex]\(2p_x\)[/tex] but is oriented along the y-axis. It has lobes extending along the y-axis in opposite directions and zero electron density in the x and z directions, making it parallel to the y-axis.
3. [tex]\(2p_z\)[/tex]: This orbital is oriented along the z-axis. It has lobes extending along the z-axis in opposite directions and zero electron density in the x and y directions, making it parallel to the z-axis.
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How can an isotope like carbon 14 be used to date dead organisms?
Which of the following statements about asteroids is true?
A.
Asteroids vary greatly in size and are mostly made up of frozen water and gas.
B.
Asteroids vary greatly in size and are mostly made up of stone, iron and nickel.
C.
Asteroids are all very large and are mostly made up of stone, iron and nickel.
D.
Asteroids are all very large and are mostly made up of frozen water and gas.
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