Answer:
The correct answer is number 2: herbicides can increase crop yields by killing weeds.
Explanation:
Herbicides are chemiclas used to avoid the spreding of undesired plants (weeds) on crops. These weeds would be prejudicial to the harvest, therefore, herbicide use can increase crop yields.
If the water in a bathtub and a teacup are the same temperature, how do the amounts of their thermal energy compare?
A. They both have the same amount of thermal energy.
B. The teacup has more thermal energy.
C. Thermal energies are equal, with different numbers of joules.
D. The filled bathtub has more thermal energy.
Suppose you have an Internet friend who study chemistry just like you are your friend claims the change from liquid water to water vapor is a chemical change write a brief email that might convince your friends otherwise
Final answer:
The change from liquid water to water vapor is actually a physical change, not a chemical change, because the molecular structure of water remains unchanged in both states. Physical changes only affect the form, not the composition, whereas chemical changes involve new substances being created.
Explanation:
Dear Friend,
I understand why you might think that the change from liquid water to water vapor is a chemical change, but in fact, it's a physical change. When water boils and becomes steam, it's simply undergoing a phase change; the molecular structure of water (H₂O) remains the same in both its liquid and gas states. This means that it's still water even when it's in the form of steam.
The difference between physical and chemical changes is that physical changes only affect the form of a substance, not its chemical composition. For instance, when we see ice melting into water or water evaporating into steam, the arrangement of the molecules changes, but the molecules themselves remain intact. In contrast, chemical changes involve making or breaking chemical bonds to create new substances, like when gasoline burns or milk sours.
So, when we consider a phase change like vaporization of liquid water to steam (H₂O(l) → H₂O(g)), it is a reversible process that does not alter the composition of the substance. If you cool the water vapor, it will condense back into liquid water. The same molecule, just a different phase.
Warm regards,
Your Chemistry Friend
Match each base with its common use.
1.magnesium hydroxide A.laxative
2. sodium hydroxide B.soap
3. calcium hydroxide C.plaster
4. aluminum hydroxide D.deodorants
5. ammonium hydroxide E. household cleaner
Answer:
Many hydroxides find applications in everyday household items.
For example, Magnesium hydroxide is used as laxative. It can be consumed for this.
Sodium hydroxide is used as soap. The sodium hydroxide is melted, the essential oils are added and the soap is formed on cooling.
Calcium hydroxide is used as plaster.
Aluminium hydroxide is used as deodorant. It plugs the sweat pores to prevent more sweat.
Ammonium hydroxide is used as household cleaner. Ammonium hydroxide dissolves grease and other dirt.
Answer:
the answer is calcium hydroxide
Explanation:
cause it is bro trust me
Where is most of the high-level waste from nuclear reactors stored?
WILL GIVE BRAINIEST.
the ocean
abandoned salt domes
at reactor site
natural caves
Is mass conserved when 40 G of sodium hydroxide undergoes a chemical change during an interaction with 36.5 grams of hydrogen chloride?
Mass is conserved during the chemical reaction between sodium hydroxide and hydrogen chloride, meaning the total mass of reactants equals the total mass of products, which will be 76.5 g after the reaction.
Yes, mass is conserved when 40 g of sodium hydroxide (NaOH) undergoes a chemical change during an interaction with 36.5 grams of hydrogen chloride (HCl). According to the law of conservation of mass, the mass of the reactants in a chemical reaction equals the mass of the products.
For instance, in the reaction NaOH (aq) + HCl(aq) → NaCl(aq) + H2O(l), the mass of NaOH and HCl before the reaction will equal the mass of NaCl and H2O formed after the reaction.
To further explain with an example, if we start with 40 g of NaOH and 36.5 g of HCl, the total mass of reactants is 76.5 g. After the reaction, we will also have 76.5 g of products, divided between NaCl and H2O.
Students can use _________ to distinguish pure substances, such as elements and compounds with a constant composition, from other substances. A) color B) density C) particle size D) state of matter
Answer is: B) density.
Pure substance is made of only one type of atom or only one type of molecule, it has definite and constant composition with distinct chemical properties.
Mixtures are physical combinations of pure substances that have no definite or constant composition.
With constant composition density of pure substance is always the same and in other substances it can vary according the composition.
Density is a measure of mass per unit of volume.
The SI derived unit for density is the kilogram/cubic meter, but chemist usually use gram per cubic centimeter.
A plant grows three inches in a month. Why is this a physical change?
A. The Size of a plant has changed
B. The plant makes energy from the sun to grow the flower
C. Heat of combustion from the sun helps the flower grow
D. Special structures in the plant react with sunlight to make the flower
The Size of a plant has changed is an example of physical change.
What is a physical change?
A physical change is a type of change in which the form of matter changes but the substance itself does not change. For instance, it can alter size or shape without causing a chemical reaction.
One or more chemicals can transform chemically into one or more new and distinct substances. Another name for it is a chemical reaction. As a result, it is clear that a chemical change is essentially a chemical reaction that involves atom rearrangement.
Therefore, The Size of a plant has changed is an example of physical change.
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What are two main ways that minerals are classified
The two main ways that minerals are classified are :
Chemical compositionPhysical propertiesMinerals are classified based on the chemical composition ( chemical properties ) and physical properties which are usually the basis by which most substances in nature are classified as well.
Some of the chemical properties by which elements are classified are ; resistivity, conductivity and acidity while some physical properties by which minerals are classified includes , boiling point , shape and color .
Hence we can conclude that The two main ways that minerals are classified are Chemical composition, Physical properties
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Which model of the atom was modeled after the solar system? Question 2 options: Dalton's model Thomson's model Rutherford's model Bohr's model
Answer is: Bohr's model.
According to the Bohr model of the atom:
1. Energy levels of electrons are discrete (certain discrete values of energy)., that is why hydrogen shows discrete, bright, colored lines.
2. Electrons orbit the nucleus in orbits that have a set size and energy.
3. Electrons can jump from one energy level to another, absorbing or emitting electromagnetic radiation with a frequency ν (energy difference of the levels).
According to Steno's principle of superposition, where can the older layers of rock be found?
A: at the top
B: in the middle
C: at the bottom
D: anywhere
Answer: The answer is C
Explanation: U lied i just got it wrong please check over your answer before assuming the answer.
According to Steno's principle of superposition, The lower layer of the rock will be found at the bottom. The correct option is C.
What is steno's principle of superposition?According to Steno's theory of horizontality, the sediment layers were first gravitationally deposited horizontally or flat on the earth's surface. It is a technique for relatively aging rocks and fossils that have accumulated horizontally on the earth's surface.
For the investigation of tilted and folded strata, this theory is crucial. The oldest rock strata can be located there, according to Steno's superposition principle, at the bottom.
At first, Steno made the assumption that if a rock contained fossils of marine animals, the rock had been formed by sediments deposited on the seafloor. Then, by raising these rocks, mountains were created. Sediment builds up on top of itself to form rocks.
Therefore, the correct option is C: at the bottom.
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What is true of sexual reproduction that brings together genetic material from two parents?
List the Earth names for the 30 alien elements in order of atomic number
The earth names for the first 30 elements, in order of their atomic number (which is also equal to the number of protons in their nucleus), range from Hydrogen (1 proton) to Zinc (30 protons).
Explanation:The earth names for the 30 elements, in order of atomic number, include the following: Hydrogen (1 proton in its nucleus), Helium (2 protons), Lithium (3 protons), Beryllium (4 protons), Boron (5 protons), Carbon (6 protons), Nitrogen (7 protons), Oxygen (8 protons), Fluorine (9 protons), Neon (10 protons), Sodium (11 protons), Magnesium (12 protons), Aluminum (13 protons), Silicon (14 protons), Phosphorus (15 protons), Sulfur (16 protons), Chlorine (17 protons), Argon (18 protons), Potassium (19 protons), Calcium (20 protons), Scandium (21 protons), Titanium (22 protons), Vanadium (23 protons), Chromium (24 protons), Manganese (25 protons), Iron (26 protons), Cobalt (27 protons), Nickel (28 protons), Copper (29 protons), and finally Zinc (30 protons).
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fast pls..,.,,..,,.,.,.
If 6.50 g of the unknown compound contained 0.217 mol of C and 0.433 mol of H , how many moles of oxygen, O , were in the sample?
Answer : The moles of oxygen in the sample was 0.216 mole.
Explanation : Given,
Moles of C = 0.217 mol
Moles of H = 0.433 mol
Mass of unknown compound = 6.50 g
Molar mass of C = 12 g/mol
Molar mass of H = 1 g/mol
Molar mass of O = 16 g/mol
First we have to calculate the mass of C and H.
[tex]\text{Mass of C}=\text{Moles of C}\times \text{Molar mass of C}[/tex]
[tex]\text{Mass of C}=0.217mol\times 12g/mol=2.604g[/tex]
[tex]\text{Mass of H}=\text{Moles of H}\times \text{Molar mass of H}[/tex]
[tex]\text{Mass of H}=0.433mol\times 1g/mol=0.433g[/tex]
Now we have to calculate the mass of oxygen.
Mass of oxygen = Mass of unknown compound - [Mass of C + Mass of H]
Mass of oxygen = 6.50 - [2.604 + 0.433]
Mass of oxygen = 3.463 g
Now we have to calculate the moles of oxygen.
[tex]\text{Moles of O}=\frac{\text{Mass of O}}{\text{Molar mass of O}}[/tex]
[tex]\text{Moles of O}=\frac{3.463g}{16g/mol}=0.216mol[/tex]
Therefore, the moles of oxygen in the sample was 0.216 mole.
Which of the following neutral atom configurations satisfies the octet rule?
A. 1s2 2s2 2p6 3s2 3p6
B. 1s2 2s1
C. 1s2 2s2 3s2 3p4
D. 1s2 2s2 3s2 3p6 4s1
Which group of atoms always has a complete octet, a full s and p orbital at the end of the configuration?
A. alkaline earth metals, Group 2A
B. halogens, Group 7A
C. noble gases, Group 8A
D. transition metals
A neutral atom of sodium (Na) has 11 electrons and an electron configuration of 1s2 2s2 2p6 3s1. How will it ionize to achieve an octet in its valence shell?
A.It will gain 7 electrons in the 3rd energy level to have a valance configuration of 3s2 3p6.
B.It will lose 1 elecrtron for the 3rd energy level to have a valance configuration of 1s2 2s2 2p6
C.It will not ionize, it already has an octet of electrons in its valance shell.
The electronic configuration which satisfy octet rule is option A. The group which have a complete octet always is noble gas group. Thus option C is correct. The sodium atom will lose electron to achieve octet rule. Thus option B is correct.
What is octet rule ?According to rule of octet, the atom which attains 8 electrons in its valence shell is said to be stable. Thus every atoms are thriving to attain stability by taking part in reaction through which they can gain or lose electrons.
In the given electronic configuration option A satisfy the octet rule, since, it have 6 electrons in its valence shell which are located in 3s and 3p.
Group 18 namely noble gas elements have completely filled valence orbitals and thus, they need no electrons or they cannot lose electrons to maintain their stability. Thus, option C is correct.
Sodium contains 1 electron in its valence shell. If it lose that one electron and ionizes to Na+ then the its next shell containing 8 electrons will be stable and thus option B is correct.
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A double replacement reaction can be best described as a reaction in which
A)a substitution takes place.
B)two atoms of a compound are lost.
C)ions are exchanged between two compounds.
D)electrons are exchanged between two atoms.
Option C= ions are exchanged between two compounds.
ExplanationA double displacement reaction, also known as a double replacement reaction or metathesis, is a type of chemical reaction where two compounds react, and the positive ions (cation) and the negative ions (anion) of the two reactants switch places, forming two new compounds or products. For example,
Na2S + 2HCl → H2S + 2NaCl
Option D is incorrect because electrons are exchanged between the atoms in oxidation –reduction reactions.
Answer:
C.) ions are exchanged between two compounds. Edge 2020.
28) Air can be considered a mixture. Which statement helps describe air? A) Air contains a fixed ratio of atoms. B) The components of air separate into visible layers. C) The components of air can be separated by chemical means. D) The exact mixture of components varies from point to point.
Answer: The answer is D
Explanation:
The mixture you separated was a mixture of iron filings, sand, and salt. Based on your understanding of matter, is this mixture a homogenous mixture or heterogenous mixture? How do you know?
homogenous mixture-the parts are not uniformly mixed
homogenous mixture-the parts are uniformly mixed
heterogenous mixture-the parts are not uniformly mixed
heterogenous mixture-the parts are uniformly mixed
How many protons are in an element with an atomic number or 8 and a mass number of 18?
how long does it take a snail travel a distance of 3ft at 0.1ft/sec
What contains pigments that absorb light energy
After analyzing rock core samples in an area with frequent earthquakes, many geologists believe a severe earthquake will occur in the area in the next 50 to 80 years. Other geologists, however, believe that such a prediction cannot be determined from the data collected. If these two groups of scientists have access to the same data, how can they form such different hypotheses?
A. Geologists manipulate data to fit their hypotheses, which results in different conclusions.
B. Scientific predictions must list every possible outcome to make sure that they are never incorrect.
C. Geologists have different specialties that can cause them to interpret data differently.
D. Scientific hypotheses need to be proven many times, so predictions of earthquakes are probably incorrect.
Answer: C. Geologists have different specialties that can cause them to interpret data differently.
Explanation:
The data is the outcome of a research study that is obtain after the implementation of the experimental methodology or by direct observation. The interpretation of data can vary among the scientists as they may have different perspective, knowledge and experience.
Thus according to the given situation, on the examination of rock samples in an area which exhibit frequent earthquakes, one type of geologists believe that a severe earthquake will occur and others believe that the prediction cannot be known by the data. This is indicating towards the fact that geologists in the given study may have different expertise, knowledge and perception which make them to interpret the data differently.
A student is trying to calculate the density of a ball. She already knows the mass, but she needs to determine the volume as well. Which of the following formulas can be used to calculate the volume of the ball?
V equals four-thirds times pi times r cubed
V equals one-third times pi times r squared times h
V = s3
V = πr2h
Answer:
A. V equals four-thirds times pi times r cubed
If Earth was like a hardboiled egg, which part of Earth would the egg shell represent and why?
Crust, as its depth is up to 3,000 kilometers
Mantle, as its depth is up to 3,000 kilometers
Mantle, as its depth is less than 100 kilometers
Crust, as its depth is less than 100 kilometers
The part of the Earth that the shell of the hard boiled egg that would represent is ; ( D ) The crust as its depth is less than 100 kilometers
The shell of the hard boiled egg is the outermost part of the egg and it account for very little percentage of the overall volume of the egg just as the earth's crust is the outermost part of the earth which is also a component of the lithosphere and does not run deep into the Earth's mantle ( less than 100 kilometers).
Hence In Conclusion the part of the earth that the shell of the hard boiled egg that would represent is ; ( D ) The crust as its depth is less than 100 kilometer
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in the formula for water (H2O) what does the subscript 2 indicate?
The subscript 2 indicates there are two hydrogen atoms in the compound
The number of atoms of any element in the given chemical formula is the number that is written on the foot of the symbol of that element. The total number of Hydrogen atoms is 2 which is written as subscript.
What is atom?Atom is the smallest particle of any matter. Atom combines to form element and element combine to form molecule or compound.
The total mass of atom is inside the nucleus. Inside the nucleus proton and neutron is there. So calculate mass of an atom, total mass of all protons is added to the total mass of neutron. Electrons revolve around the nucleus.
In our question, the number written on the foot of element Hydrogen in water H₂O is the number of atoms of Hydrogen. We can read the formula of water as one atom of oxygen react with 2 atom of hydrogen to make one molecule of water
Therefore the subscript 2 indicate the number of hydrogen atoms
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Where should the author of a case study introduce the central question of the text?
The author of a case study should introduce the central question in the beginning of the text.
What is a case study?
Case study is an examination on a particular case, be it person, group, or event, in real world context. It will be based on a particular central question. So, the case study is mainly intended to answer the central question.
The central question is the question that can be asked about the topic in the first part of the case study.
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When might a technique called water displacement be used?
which of these is an example of a chemical change?
A. Leaving Cheese out to get moldy
B. Smelling Sprayed perfume
C. Feeling the ice melt on your skin
D. Crushing ice with a hammer
Answer: A. Leaving Cheese out to get moldy
Explanation:
A physical change is defined as a change in which there is alteration in shape, size etc. No new substance gets formed in these reactions.
Example: Smelling Sprayed perfume : It is only diffusion of gas.
Feeling the ice melt on your skin: It is only change of state.
Crushing ice with a hammer: It is only change of shape.
A chemical change is defined as a change in which a change in chemical composition takes place. A new substance is formed in these reactions.
Example: Leaving Cheese out to get moldy : It involves oxidation of cheese to form new substances.
Thus Leaving Cheese out to get moldy is a chemical change.
What is the symbol for molarity?
The answer in chemistry is mol/L and altho it is represented by the symbol M usually.
Answer:
the answer is "M"
Explanation:
capital M not lower m
What is the volume of an aluminum cube whose edges are 10 cm long?
volume is length*with*height so 10*10=100*10=1000