Answer:
B is correct.
Explanation:
A vaccination will trigger the organism to prepare antibodies as a measure of protection against a sickness.
Formulate a hypothesis based on something recently observed.
And How could this hypothesis be tested?
Answer:
If garlic repels fleas, then a dog that is given garlic every day will not get fleas. Bacterial growth may be affected by moisture levels in the air. If sugar causes cavities, then people who eat a lot of candy may be more prone to cavities.
Explanation:
2. Is the following sentence true or false? Most earthquakes generate
tsunamis.
PLEASE HELP!!!
ILL MARK AS BRAINIEST AND GIVE YOU 30 POINTS!!!
Answer:
did u get it yet
Explanation:
13. A natural flow of groundwater that has
reached the surface is a(n)
a. spring.
c. aquifer.
b. well.
d. travertine.
A natural flow of ground water that has reached surface level is call a spring.
Water moves underground downward and sideways, in great quantities, due to gravity and pressure.
A spring is the result of an aquifer being filled to the point that the water overflows onto the land surface. They come in different sizes, from intermittent seeps, which flow only after much rain, to huge pools flowing hundreds of millions of gallons daily.
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A sample of a certain gas has a volume of 452 mL at 711 mmHg and 26 degrees C. What would be the volume of this same sample of gas if it were measured at STP
The volume of this same sample of gas if it were measured at STP is 386.09mL
HOW TO CALCULATE VOLUME:
The new volume of a gas sample can be calculated using the following expression:
P1V1/T1 = P2V2/T2
Where;
P1 = initial pressureP2 = final pressureV1 = initial volumeV2 = final volumeT1 = initial temperatureT2 = final temperatureAccording to this question, a sample of a certain gas has a volume of 452 mL at 711 mmHg and 26°C (299K).
(711 × 452)/299 = 760 × V2/273
1074.82 = 2.78V2
V2 = 1074.82 ÷ 2.78
V2 = 386.09mL
Therefore, the volume of this same sample of gas if it were measured at STP is 386.09mL.
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which of the following best describes a single replacement reaction?
two elements combine to form a compound
one element takes the place of another in a compound
two elements switch places in a compound
a compound breaks into separate elements
Answer:
One element takes the place of another in a compound
Explanation:
I just took a test for it and got it right. :)
Hope This Helps :)
How many molecules are present in this formula? 3H2 (SO)4
Molecules are formed when two or more atoms chemically bond together. In 3H₂(SO)₄, three molecules are present.
What are molecules?Molecules are the smallest unit present in any compound and are formed by a group of atoms. A number denoted in front of the chemical species is the coefficient that represents the number of molecules.
The coefficient present in front of the reactant or the product in a chemical reaction gives the number of the molecules present in a compound. As three is denoted in front of the sulphuric acid, hence will be the number of the molecules.
Therefore, there are three molecules present in sulphuric acid.
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why is it hotter in the summer and colder in the winter?
Answer: During the summer, the sun's rays hit the Earth at a steep angle. ... Also, the long daylight hours allow the Earth plenty of time to reach warm temperatures. During the winter, the sun's rays hit the Earth at a shallow angle. These rays are more spread out, which minimizes the amount of energy that hits any given spot.
Could someone help me with this?
Solving part-1 only
#1
KMnO_4
Transition metal is Manganese (Mn)#2
Actually it's the oxidation number of Mn
Let's find how?
[tex]\\ \tt\Rrightarrow x+1+4(-2)=0[/tex]
[tex]\\ \tt\Rrightarrow x+1-8=0[/tex]
[tex]\\ \tt\Rrightarrow x-7=0[/tex]
[tex]\\ \tt\Rrightarrow x=+7[/tex]
x is the oxidation number#3
Purple as per the color of potassium permanganate#4
[tex]\boxed{\begin{array}{c|c|c}\boxed{\bf Tube} &\boxed{\bf Charge} &\boxed{\bf No\:of\; electrons\: loss}\\ \sf 2 &\sf +6 &\sf 6e^-\\ \sf 3& \sf +2 &\sf 2e- \\ \sf 4 &\sf 4 &\sf 4e^-\end{array}}[/tex]
How do chemists predict the shapes of molecules?
Due to the repulsion between electrons, valence electrons will be arranged as close to each other as possible.
Due to the attraction between electrons, valence electrons will be arranged as close to each other as possible.
Due to the repulsion between electrons, valence electrons will be arranged as far apart from each other as possible.
Chemists can't predict the shape of molecules, because the attractive forces between valence electrons are unpredictable.
A. Due to the repulsion between electrons, valence electrons will be arranged as close to each other as possible.
The approximate shape of a molecule can often be predicted by using what is called the valence-shell electron-pair repulsion (VSEPR) model.Electrons in bonds and in lone pairs can be thought of as a charge cloud that repels one another and stay as far apart possible, thus causing molecules to assume specific shapes.The shape of a molecule is determined by the location of the nuclei and its electrons.Therefore, the correct option is A.
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Part A
Before you design your model village, write down the problems you observed in task 1. What were the largest risks to the community? What happened to the homes?
The largest risks while designing a model to withstand a village include that the model does not mitigate the effects of the tsunami or only mitigates the effects partially, which would cause damages to the homes.
Designing a model to withstand the effect of any natural phenomenon such as an earthquake, fire or tsunami is not an easy task and will require the following cycle:
Designing the model.Testing the model.Making changes or designing a new model.In the case of a model for tsunamis, it is likely the following problems occur:
The model does not protect the houses from tsunamis.The model does not protect the houses completely.This would lead to negative effects such as:
Damages in the houses.Dead or injured people.Destruction of infrastrcture.Note: This question is incomplete because the context is missing; here is the missing part.
Protecting Your Model Village from Tsunamis this task, you will design a model village to withstand the effects of a tsunami.
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15) The chemical formula of a compound indicates the
A) relative proportions of the elements in the compound
B) identity of the elements in the compound only
C) type and arrangement of the bonds in the compound
D) three-dimensional structure of the compound
The particles in a metal are held together by strong __________ bonds. What word describes the type of bond to complete this sentence?
Answer:
metallic
Explanation:
The dislocated electrons moving around the protons create opposite charges with electrostatic attraction between them that are very strong, and are called metallic bonds.
The particles in a metal are held together by strong metallic bonds . The metals forms crystalline solids with highly ordered lattice structure.
What are metals?Metals are electropositive elements. They are rich in electrons and easily donate their electrons with non-metals to form ionic bonds. Metals gain positive charge by losing electrons.
Metals in periodic table are classified as s block elements that are alkali metals and alkaline earth metals and d-block elements that are transition metals.
Metals forms highly ordered crystal lattice 3 D structures in which metal ions negative ions or electrons are bonded by strong intermolecular force called metallic bonds and the free electrons are located in the interstices.
These electrons can delocalize and conduct thermally and electrically.Hence, the bond which hold the particles in a metal is called metallic bond.
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what is a “ medium” in regards to waves ?
Which of the following giant covalent structures does not have a high melting and boiling
point?
a) Polythene
b) Graphite
c) Silicon dioxide
d) Diamond
Answer:
Polythene has the lowest melting/boiling point from all the other covalent structures mentioned in this question.
Answer:
Polythene (polyethene according the IUPAC nomenclature.)
Explanation:
Consider the structure of each option:
Polythene: long chains of atoms that are able to rotate along the bonding axis. Graphite: layers of (hexagonal) carbon sheets; each individual sheet is rigid (allows no rotation.) Silicon dioxide: three-dimensional (tetrahedral) network of carbon and oxygen atoms; the entire network very rigid (allows no rotation.)Diamond: three-dimensional (tetrahedral) network of carbon atoms; likewise, the entire tetrahedral network is very rigid.Melting each structure requires overcoming the forces that hold the structure rigid:
In polythene, van der Waal forces hold the chains together and prevents rotations.Deshaping graphite requires bending the layers; doing so would require overcoming the covalent bonds within the hexagonal sheets.In silicon dioxide and diamond, deshaping the tetrahedral network also requires overcoming covalent bonds.Van der Waal forces are much easier to break than covalent bonds.
Hence, the melting point of polythene would be the lowest among the options.
Knowing that the solubility of a salt at 80°C is 45g/100 g of H,O, calculate the mass of water required for dissolve 250 g of this salt at 80º C.
The mass of water required will be approximately [tex] \bf = 555.6\: g [/tex].
To solve this question, just make a simple rule of three between the amount of salt dissolved at 80ºC and the mass of water:[tex]\qquad[/tex] 45g of salt [tex] \sf \longrightarrow[/tex] 100g of H₂O
[tex]\qquad[/tex] 250g of salt [tex] \sf \longrightarrow[/tex] x g of H₂O
[tex]\qquad[/tex] [tex]\red{\twoheadrightarrow\bf45\times x = 250\times 100}[/tex]
[tex]\qquad[/tex] [tex]\twoheadrightarrow\sf45x=25000[/tex]
[tex]\qquad[/tex] [tex]\twoheadrightarrow\sf x=\cancel{\dfrac{25000}{45}}[/tex]
[tex]\qquad[/tex] [tex]\red{\twoheadrightarrow\bf x = 555.6\:g}[/tex]
Therefore, knowing that the solubility of a salt at 80ºC is 45g/100g of water (H₂O), the mass of water needed to dissolve 250g of this salt at 80ºC will be [tex] \red{\bf = 555.6\: g }[/tex]__________________________________________________
can somebody please help me here ? i wanna make sure of my answer..
Answer:
[Unfortunately] Answer is A
Explanation:
You should know that 'liquid' is a state of matter and aqueous means that there is water present.
-It is mentioned that barium chloride is a solution. So you can cut off the C option.
-Barium sulfate is a salt which means it's a solid, so you can cut off the D option.
We now have A and B as the only options remaining.
-Dilute sulfuric acid is definitely not a liquid because water is present. (dilute indicates that there is a greater proportion of water)
The answer should be A.
how many moles are in 8.32 × × times 10^24 molecules of co2?
Answer:
13.8 moles
Explanation:
You know that in a mole you have 6.022x10²³ something in this case of molecules. By knowing that by each mole you have 6.022x10²³ molecules, then you can establish the factor of conversion:
8.32x10²⁴molec of CO2 x 1 mol/6.022x10²³ molec of CO2
You divide 8.32x10²⁴/6.022x10²³ and you get 13.81 moles.
Helppppp asaapppppp plzzzzzz
Answer:
Alright the very first thing you need to do is balance the equation:
2HCl + Na2CO3 -----> 2NaCl + CO2 + H2O
Now we need to find the limiting reactant by converting the volume to moles of both HCl and Na2CO3.
Volume x Concentration/molarity = moles
0.235L x 0.6 M = 0.141 moles / molar ratio of 2 = 0.0705 moles of HCl
0.094L x 0.75 M = 0.0705 moles /molar ratio of 1 = 0.0705 moles of Na2CO3
Since both of the moles are equal, it means the entire reaction is complete (while the identification of limiting reactant may seem like an unnecessary step, it's quite essential in stoichiometry, so keep an eye out) and there is no excess of any reactant.
Now we know that the product we want to calculate is aqueous so, following the law of conservation of mass, we should add both volumes together to calculate how much volume we could get for NaCl.
0.235 + 0.094 = 0.329L of NaCl
Now we apply the C1V1 = C2V2 equation using the concentration and volume of Na2CO3 because it's molar ratio is one to one to NaCl (You can also use HCL, but you have to divide their moles by 2 for the molar ratio) and the volume we just calculated for NaCl.
(0.75M) x (0.094L) = C2 x (0.329L)
Rearrange equation to solve for C2:
(0.75M) x (0.094L) = C2
(0.329L)
C2 = 0.214 M (Rounded)
When the reaction is finished, the NaCl solution will have a molarity concentration of 0.214 M.
An endothermic reaction occurs when water and ammonium nitrate are combined. Which of the following statements correctly
describes the energy changes in the reaction?
OA. Energy is released because the reactants have more chemical energy than the products.
OB. Energy is absorbed because the reactants have more chemical energy than the products,
OC. Energy is absorbed because the products have more chemical energy than the reactants.
OD. Energy is released because the products have more chemical energy than the reactants.
Answer:
C.Energy is absorbed because the products have more chemical energy than the reactants.
Explanation:
look at the picture
Answer:
The strong electric force.
Explanation:
Trust me. If its wrong, comment on this, don't delete it. If someone else answers with the wrong question than other students might get the answer wrong. So if its right, say that it is, if its wrong, tell others what the real answer is.
which describes an attribute of nonrenewable resources
Answer:
atributes of nonrenewable recources are things you cant re use after 1 use like gas
Explanation:
Answer: the answer is b. Are unlimited
Explanation:
When the equation for the reaction represented below is balanced and all coefficients are reduced to lowest whole-number terms, the coefficient for Al(s) is __ Al(s) + __ O2(g) __ Al2O3(s)
This question is asking for the correct balanced reaction, when solid aluminum reacts with gaseous oxygen to form solid aluminum oxide, according to the law of conservation of mass, which demands us to have the same number of atoms of each element on both sides of the equation.
In such a way, we can start by knowing there is one aluminum atom on the left and two on the right whereas there are two oxygen atoms on the left and three on the right side of the equation.
The aforementioned means we must balance oxygen first by putting a 2 on aluminum oxide and a 3 on oxygen in order to cross multiply and obtain six oxygen atoms on both sides of the equation.
Moreover, the 2 on the aluminum oxide makes four aluminum atoms on the right, which means we must put a 4 on the left-handed aluminum in order to get the correct balance, and therefore, write the following balanced equation:
4Al(s) + 3O₂(g) ⇒ 2Al₂O₃(s)
Hence, the coefficient for Al, as asked, is 4.
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Answer:
0.178M
Explanation:
The question can immediately be understood as comparing two states.
- The initial state M1 , V1.
- The Final state M2 , V2.
M - Molarity.
V - Volume (in mili liters/ml/ in this case).
The formula is stated as:
M1 * V1 = M2 * V2
Given- Required
M1 = 0.125M V1 = 265ml M2 = ?
V2 = 186ml
Plug these values into the formula above and divide V2 to get M2.rearranged formula - M2 = M1 * V1 / V2 = 0.125M * 265ml / 186ml
= 0.178091397 M ~ ~ 0.178M.
Pls Help Me (20 Points)
In one to two sentences, explain how to compare the strength of electrostatic forces between molecules in salt water to the strength of electrostatic forces between molecules in freshwater. Include a description of the data to be collected and how that data would allow one to draw conclusions about the relative strengths of the electrostatic forces in the two substances.
Answer:
-Salts are composed of ions that form a tightly packed and ordered network, which is called a crystal lattice, and it is held together by ionic bonds.
Explanation: salts are ionic compounds, which are composed by oppositely charged ions (cations and anions) which are bonded each other by ionic bonds, in an ordered arrangement, often a crystalline solid.
-When a salt is added to a polar solvent like water, the ions interact with the solvent molecules via ion-dipole forces, which overcome the forces originally holding the ions together.
Explanation: the molecules of a polar solvent are dipoles because they have dipolar momentum (a difference in charge due to a electronegativiy difference). When a salt is dissolved in a polar solvent, it dissociates in ions. So, the resulting interactions between these species are ion-dipole forces.
-The ions are then isolated and stabilized in solution via these interactions, and when this occurs for most of the salt compound, it is considered soluble in that solvent.
Explanation: the ions in solution are surrounded by solvent molecules which stabilizes them. A salt which is enterely dissolved in a solvent is soluble in that solvent.
-Due to the nature of the interaction between ions and solvent molecules, a concentration of ions can be dissolved higher in water than in alcohol.
Explanation: water molecules have unique properties that make water an universal solvent. Due to these properties and its polarity, water can dissolve larger quantities of salt than other polar solvents such as alcohol.
The electrostatic force in water without salt is stronger as compared to the water due to the presence of free electrons.
In water hydrogen bonding is present that is the only kind of electrostatic force present in the water. In water containing salt sodium and chloride ions are present which conduct strong electrostatic force. A static meter is ideal for measuring the of liquids. It measures the charge on the liquid. Hence, the electrostatic force in salt water is stronger as compared to the water due to the presence of free electrons.Learn more about electrostatic:
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name a metal and non metal which are liquid at normal pressure and temperature
Answer:
metal : Mercury(Hg)
non metal : bromine (Br)
Explanation:
mercury is liquid at room temperature and pressure and the same as bromine
Which model of the atom is thought to be true?
A. Protons, electrons, and neutrons are evenly distributed throughout the volume of the atom.
B. The nucleus is made of protons, electrons, and neutrons.
C. Electrons are distributed around the nucleus and occupy almost all the volume of the atom.
D. The nucleus is made of electrons and protons.
Answer:
Hi the answer should be B or 2
Explanation:
Hope this helps!
how much water will you need to add to your working solution to get to a 100 ml total volume of a 0.03m nacl solution?
Answer:
The solution is made by adding 4.38 g NaCl to a 250-mL volumetric flask. About 100 mL of water are added and when all the NaCl dissolves water is added up ...
What is the mass of air in room
Answer:
the mass of the air in the room is 4.96512 kg ( in 0°C)
What has a larger mass, a mole of oxygen gas or a mole of neon gas?
Answer:
1 mole ozone gas
Explanation:
Since atomicity of Ozone (3) is maximum so, it will contain maximum number of atoms.