Answer:
True
Explanation:
the time you plant crops matters alot. especially in times before pesticides and greenhouses.
Answer: False
Explanation:
People went by what the seasons were to find out what to grow. Calendars merely helped with remembering important dates like when is Halloween, when is president's day, etc..
PLEASE SOMEONE ANSWER
an isotope of phosphorus contains 19 neutrons. construct the symbol for the isotope.
Isotope of phosphorus containing 19 neutrons can represented as ²⁴₁₅P.
Isotopes are those atoms of the same elements that have same number of protons or same atomic number but different mass number.
Atomic number = number of protons in the atom = number of electrons in the neutral atom
Mass number = number of protons + number of neutrons
Mass number is represented as Z
Atomic number is represented as A.
While writing the symbol of an atom the mass number is written on the left and side and as a superscript to the symbol of the atom and atomic number is written to the left and as a subscript to the symbol.
Rock salt is a mixture of salt sodium chlorine and sand describe how you separate rocksalt to obtain salt crystals and pure dry sand. This question is worth 6 marks so please fill enough points
Answer:
pour the rock salt mixture through a filter made from paper and allow the liquid to filtrate
Explanation:
Separating Sand and Salt
Probably the easiest method to separate the two substances is to dissolve salt in water, pour the liquid away from the sand, and then evaporate the water to recover the salt.
what occurs when the concentration of glucose in the water outside of a cell is higher than the concentration inside?
Answer:
Glucose will enter the cell through osmosis.
Explanation:
Diffusion causes molecules to move from high concentration to low concentration, so the glucose molecules outside the cell will move through the membrane to inside of the cell.
Scientific explanations are based on objective and systematic observations carried out under carefully controlled conditions
Answer:
Yes, its carried out under carefully controlled conditions because it might some times have a negative impacts towards humans.
what substances serve many purposes in the purposes in the attempt to move molecules across a plasma membrane
Carrier proteins serve many purposes in the purposes in the attempt to move molecules across a plasma membrane.
What are carrier proteins?Carrier proteins are proteins which are found n the surfaces of cell membranes which serve the function of transporting molecules across the cell membrane barrier.
The carrier proteins transport various molecules across the cell membrane.
Carrier proteins transport such molecules as sugars, proteins, ions, lipids across the membrane.
Some carrier proteins expend energy in the form of ATP when they transport molecules across the cell membrane.
Some use the concentration gradient of cells to transport molecules across the cell membrane.
The carrier proteins which expend energy to transport molecules are involved in active transport.
The carrier proteins that do not expend energy are involved in passive transport.
In conclusion, carrier proteins are essential in the transport of molecules across the plasma membrane.
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fertilizer is sold in 100 pound bags labelled with the amount of nitrogen ( n), phosphoric acid ( p2o5), and potash ( k2o) present. the mixture of these nutrients varies from one type of fertilizer to the next. for example, a pound bag of vigoro ultra turf fertilizer contains pounds of nitrogen, pounds of phosphoric acid, and pounds of potash. another type of fertilizer, parker’s premium starter, has pounds of nitrogen, pounds of phosphoric acid, and pounds of potash per pounds. determine the amount of each type required to yield a mixture containing the pounds of nitrogen, pounds of phosphoric acid, and pounds of potash.
The amount of each type required to yield a mixture containing the pounds of nitrogen, pounds of phosphoric acid, and pounds of potash is y = 5 bags, x = 3 bags.
What are fertilizers?Fertilizers are any material of natural or synthetic origin that is applied to soil or to plant tissues to supply plant nutrients.
177 pounds = 29x + 18y (1)
Where x is bags of Vigor Ultra Turf fertilizer and y are bags of Parkers Premium Starte-
For P₂O₅:
134 pounds = 3x + 25y (2)
For K₂O:
42 pounds = 4x + 6y (3)
Replacing (1) in (2):
134 = (531/29 - 54y/29) + 25y
3355/29 = 671y/29
Thus, y = 5 bags, x = 3 bags.
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A biochemist performs an experiment to study the behavior of water molecules near proteins. he concludes that water molecules occur in groups of five in the presence of proteins. skepticism is important in this scenario because it would help him to learn from the investigations of his colleagues. ask future questions related to the investigation. communicate his results at a conference. ensure that his conclusion is supported by evidence.
Its D - ensure that his conclusion is supported by evidence. Skepticism will help him remain objective towards the experiment and not become biased and believe that his finding is correct just because he worked on them.
Each molecule of water consists of one atom of oxygen and two atoms of hydrogen, so it has the chemical formula H2O. The arrangement of atoms in a water molecule, explains many of the water’s chemical properties. In each water molecule, the nucleus of the oxygen atom (with 8 positively charged protons) attracts electrons much more strongly than the hydrogen nuclei (with only one positively charged proton).
This results in a negative electrical charge near the oxygen atom (due to the "pull" of the negatively charged electrons toward the oxygen nucleus) and a positive electrical charge near the hydrogen atoms. A difference in electrical charge between different parts of a molecule is called polarity. A polar molecule is a molecule in which part of the molecule is positively charged and part of the molecule is negatively charged.
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Why is little known about the interior of the earth?
Answer:
The Earth's interior is composed of four layers, three solid and one liquid—not magma but molten metal, nearly as hot as the surface of the sun.
The deepest layer is a solid iron ball, about 1,500 miles (2,400 kilometers) in diameter. Although this inner core is white hot, the pressure is so high the iron cannot melt.
The iron isn't pure—scientists believe it contains sulfur and nickel, plus smaller amounts of other elements. Estimates of its temperature vary, but it is probably somewhere between 9,000 and 13,000 degrees Fahrenheit (5,000 and 7,000 degrees Celsius).
Above the inner core is the outer core, a shell of liquid iron. This layer is cooler but still very hot, perhaps 7,200 to 9,000 degrees Fahrenheit (4,000 to 5,000 degrees Celsius). It too is composed mostly of iron, plus substantial amounts of sulfur and nickel. It creates the Earth's magnetic field and is about 1,400 miles (2,300 kilometers) thick.
You can get more info, in national geographic.
https://www.nationalgeographic.com/science/article/earths-interior
Which of the following reactions shows a chemical change producing a gas?
A. H₂(g) + O₂(g) → H₂O()
B. 2CH3OH()+302(g) → 2C02(g) + 4H₂O()
C. NaCl(s)→ NaCl(aq)
D. 2AgNO3(aq) + CaBr₂(aq) → 2AgBr(s) + Ca(NO3)2(aq)
It’s B
2CH3OH()+302(g) → 2C02(g) + 4H₂O(l) is the reaction which shows a chemical change producing a gas.
What is chemical reaction and example?One or more chemicals change into one or more other chemicals in a chemical reaction. A chemical reaction is the transformation of one or more substances, known as reactants, into one or more new substances, known as products. Chemical components or compounds make up substances. For instance, rust is created when iron and oxygen combine. When vinegar and baking soda are combined, sodium acetate, carbon dioxide, and water are the results. things igniting or detonating.
Types of chemical reactions:There are five types of chemical reaction that occur generally, they are
Single displacement, double displacement, combustion, combination or synthesis, and decomposition.
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The solubility of o2 in water is 6. 5mg/l at an atmospheric pressure of 1. 0 atm and temperature of 40. 0 c. Calculate henrys law constant of o2 at 40c. The molar fraction of oxygen gas inair is 0. 209
The henry constant (Kh) is found to be 9.69 X 10⁻⁴moles/L atm .
The solubility of O₂ is 6.5 mg/l Or 0.0065 g/L
First we convert solubility into moles/L by dividing by molecular mass of O₂ (32 g/mole)
solubility = 0.0065/32 moles/L = 0.000203 moles/L
henry's law can be calculated by the formula, c = Kh X p , where x = mole fraction and p is partial pressure of gas, Kh is henrys constant and c is concentration.
On assuming, the percentage of oxygen in atmosphere is 20.95% and pressure is 1 atm
so partial pressure of O₂ = 20.95/100 X 1 = 0.2095 atm ( partial pressure = mole fraction X total pressure)
so now Kh = 0.000203/0.2095 = 0.000969 moles/L atm or 9.69 X 10⁻⁴ moles/L atm.
The quantity of dissolved gas in a liquid is inversely proportional to the partial pressure of the gas above the liquid, according to Henry’s law also called as Gas law. Henry constant mostly depend on the vapour pressue and solubility of the gas.
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explain how absorbance and concentration date collected in light expiriments can be used to determine the concentration of an unknown solution
The calibration curve is used to determine the concentration of an unknown solution.
What is a spectrophotometer?A spectrophotometer is a device in which the absorbance of a substance could be measured. The absorbance refers to the amount of light that could be passed through a substance.
What we do is to first select the appropriate wavelength the would be used for the study. The absorbance of the solvent without the analyte is first measured. This is called the sample blank. Then several selected concentrations of the analyte is made to interact with light in the spectrophotometer and the absorbance is measured.
This is now used to create a line of best fit called calibration curve that could be used to determine the absorbance of any other concentration of the same solution.
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Howie wants to know how many apples he could pick from his grandpa's orchard. There are 9 rows of trees and he can pick 925 apples from each row. Approximately how many apples can he pick in total? Round the larger factor to the nearest hundred to estimate.
Answer:
8,300
Explanation:
925*9 is 8325.
After you round to the nearest hundred, its 8,300.
Answer:
Explanation:
eggggggggggg
In the bicarbonate buffering system, carbon dioxide and water join to form ___________, which dissociates into hydrogen and ________________.
In the bicarbonate buffering system, carbon dioxide and water join to form carbonic acid, which dissociates into hydrogen and bicarbonate.
What is a buffering system?A buffering system can be defined as a complex solution that serves to buffer sudden changes in the pH of a given solution, which is fundamental to maintaining homeostasis.
In conclusion, in the bicarbonate buffering system, carbon dioxide and water join to form carbonic acid, which dissociates into hydrogen and bicarbonate.
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when was the last year the theory of understanding the energetics and arrangement of atoms was developed
In 1897 the theory of understanding the energetics and arrangement of atoms was developed by Josheph Larmor.
It is also called solar system model of atom.
What is solar system model of atom?The “solar system” model indicates an atom as a whole massive positive body that is the nucleus similar to the sun in the solar system with negative entities that are the electrons as the planets in our solar system revolving around it.
Why this model not accepted?The thought about this model is that the electrons which revolves around the nucleus are the charged particles which have centripetal acceleration during the revolution. Even if they all are travelling at the same velocity in modulus, the trajectory of their velocity varies with respect to time which resulting in the centripetal acceleration. An accelerated charge particle will emit energy in the form of electromagnetic radiation. This results in the loss of energy which causes the charged particle to fall inside the nucleus. Therefore, this fails to happen.
Thus, we concluded that In 1897 the theory of understanding the energetics and arrangement of atoms was developed.
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20 things before cooking
Answer:
step 1- wash the rice cooker
step2-
will a hurricane lose strength if the winds become strong? and why?
No, hurricane won't loose strength when the winds are strong.
It's because If wind conditions are okay, the storm becomes a hurricane. This heat energy is the energy for the storm. And the warmer the water, the further humidity is in the air. And that could mean bigger and stronger hurricanes.
Hurricanes increases their speed their strength because Warmer ocean face temperatures consolidate tropical storm wind pets.
These are the top 3 factors for hurricane development
Warm ocean water
Wind shear
humidity content
If hurricanes snappily lose strength as they move over land it's only because of the Friction with Land.
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A student measures the mass of a solution before and after a chemical reaction takes place. In both cases the students measures the mass to be 50. 25 g on an electronic balance with an uncertainty of 0. 05 g. The student realizes that the ranges of uncertainty for each measurement overlap exactly. Which claim can the student make?.
The student can claim: We can’t know for sure whether or not the mass changed, but it seems reasonable to claim that the mass did not change, given that the ranges of uncertainty overlap.
Since the student used the same electronic balance with an uncertainty of 0.05g to measure the mass of the solution before and after chemical reaction, the conclusion is that the masses are the same within the uncertainty of the balance.
+- value is uncertainty value of measurement.
Accuracy is the closeness of a measurement to the true value.
Balance is an instrument for comparing the mass of two bodies.
The percent error is an error between an observed value and the true value of a measurement.
Percent Error = (Actual Value - Estimated Value / Actual Value) × 100%
There are three types of error in chemistry: gross errors, random errors and systematic errors.
Missing options:
The mass definitely stayed the same because the measurement of 50.25 g was obtained each time.
The mass definitely stayed the same because the ranges of uncertainty overlap exactly.
We can’t know for sure whether or not the mass changed, but it seems reasonable to claim that the mass did not change, given that the ranges of uncertainty overlap.
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Determine the number of protons and electrons in each ion-
(a) Na
(b) Ba²+
(c) 0²-
(d) Co³+
Answer:
(a) protons: 11 electrons:11
(b) protons: 56 electrons: 54
(c) protons: 8 electrons: 10
(d) protons: 27 electrons: 24
Explanation:
A teacher adds a teaspoon of salt to his tea by mistake. He does not stir. Some students are discussing what will happen to the saltiness of the tea.
Answer:
ok so what is the question?
What does this picture represent?
Answer:
Mixture because it isn't chemically combined
Select all of the particle diagrams that represent a pure substance.
As ,in diagram D we can see that there are only one type of atoms are joined, so they are pure substances. The particle of diagrams that represent a pure substance is Option D.
What is Pure Substance ?The substance which is made up of only one kind of particle and cannot be separated into other kind of matter is called Pure substance.
Example: Gold metal, sugar, salt, copper wire, diamond etc.
These substance are of two types
ElementscompoundsHow to find which substance is pure from diagram?So, we are going to find out the pure substance from the below diagrams. All other are mixtures having different kind of element.
Thus from the above conclusion we can say that the option D represents pure substance.
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1. A student averaged 45 miles per hour on a trip. What was his speed in kilometers per
second?
Answer: 0.0201 km per second
Explanation:
45 miles per hour = 0.0125 miles per second = 0.0201 km per second
What is the name of the building block/ monomer of your macromolecule?
Answer: monomers
Explanation: Most macromolecules are made from single subunits, or building blocks, called monomers. The monomers combine with each other using covalent bonds to form larger molecules known as polymers.
The half life of a radioactive element is 20 days. How many days will it take for the radioactive sample to decay to 1/8 its size?
Answer:
it will be 60 day
Explanation:
Thomson concluded that ____ have ____ mass than the atom.
a
electrons; more
b
protons; less
c
electrons; less
d
neutrons; less
Answer: Either b or c or d. More information is needed to answer the question.
While burning coal and charcoal, you notice that coal releases more heat than charcoal. What does that mean?.
While burning coal and charcoal, you notice that coal releases more heat than charcoal. This means that the chemical potential energy in coal is higher than that of charcoal.
Combustion or burning occurs when a substance reacts with oxygen. This reaction is highly exothermic and releases high amounts of energy in the form of heat, light and sound. The amount of energy released depends on the potential chemical energy stored in the substance.
Potential chemical energy is the energy stored in a combustible substance that gets converted to heat, light and sound energy while the substance burns. The more potential chemical energy a substance has, the more energy it expels while burning.
Hence, while burning coal and charcoal, coal will release more heat energy because its potential chemical energy is higher than that of charcoal.
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Filtration is useful for separating: (1 point)
O solids from liquids or gases
compounds
O
O liquids from liquids
O solutions
Filtration is useful for separating solids from liquids or gases compounds (option A).
What is filtration?Filtration is the act or process of filtering or in chemistry, it is the mechanical separation of a liquid from the undissolved particles floating in it.
Filtration is a common separation technique employed in chemistry for the partitioning of an undissolved solid from a liquid solvent.
For example; when a mixture of sand and water is filtered, the sand stays behind in the filter paper as the residue while the water passes through the filter paper to become the filtrate.
Therefore, it can be said that filtration is useful for separating solids from liquids or gases compounds.
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Answer:
Solids from liquids or gases
Explanation:
Connexus
if 20cm3 of 0.125 moldm-3 of tetraoxosulphate(vi) acid solution reacted with a solution of sodium hydroxide, calculate the amount, in moles of sodium hydroxide required for a complete reaction
The amount of sodium hydroxide required to complete the reaction is 0.005 moles.
What is mole?Mole can be defined as a standard scientific unit for measuring large qualities of very small entities such as atom , molecules etc,
Moles can be calculated as mass of substance divided by mass of one mole.
1cm3 = 0.001 dm3
20cm3 = 0.02 dm3
To calculate amount of mole of sodium hydroxide first we have to calculate mass of tatraoxosulphate.
Molarity = mass/ volume
Mass = molarity x volume = 0.125 x 0.02 = 0.0025
2NaOH + H2SO4 -> Na2SO4 + 2H2O
Amount of moles of NaOH = 2 x mass of tatraoxosulphate
= 2 x 0.0025 = 0.005 moles
Thus, the amount of sodium hydroxide required to complete the reaction is 0.005 moles.
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a change will only occur one time. group of answer choices cyclic periodic unidirectional bidirectional
A change will only occur one time in unidirectional.
Because
Cyclic : Cyclic compounds are chemical compounds having a basic non-linear structure. In other words, these are ring structures. One or more series of atoms in the compound is connected to form a ring structure.
Periodic : The periodic table of chemical elements, often called the periodic table, organizes all discovered chemical elements in rows (called periods) and columns (called groups) according to increasing atomic number.
Unidirectional : compound is operating or moving in one direction only and it does not move in other direction.
Bidirectional : Capable of reacting or functioning in two, usually opposite, directions.
Thus, A change will only occur one time in unidirectional.
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Consider the following element 6C, Na Mg, P, S, CL, Ni :which of these can form form hydride by electovalent bonding?, Can be used to catalye a chemical reaction? , can be used in radioactive dating?, Can form an acid anhydride?, Exhibit both metallic and non-metallic behavior?
The periodic table is an arrangement of the elements in order of increasing reactivity. The elements that are more reactive are found at the left hand side of the table among the metals. The reactive non metals are found at the right hand side of the table.
Element which of these can form form hydride by electrovalent bonding - NaElement that can be used to catalyze a chemical reaction - NiElement that can be used in radioactive dating - CElement that can form an acid anhydride - Cl, P, SElement that exhibit both metallic and non-metallic behavior - NoneLearn more about the periodic table:https://brainly.com/question/11155928
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