Answer: The number of molecules present in given amount of water are [tex]1.54\times 10^{23}[/tex]
Explanation:
To calculate the number of moles, we use the equation:
[tex]\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}[/tex]
Given mass of water = 4.6 g
Molar mass of water = 18.0 g/mol
Putting values in above equation, we get:
[tex]\text{Moles of water}=\frac{4.6g}{18.0g/mol}=0.255mol[/tex]
According to mole concept:
1 mole of a compound contains [tex]6.022\time 10^{23}[/tex] number of molecules.
So, 0.255 moles of water will contain [tex]0.255\times 6.022\times 10^{23}=1.54\times 10^{23}[/tex] number of molecules.
Hence, the number of molecules present in given amount of water are [tex]1.54\times 10^{23}[/tex]
Is rust a pure substance or a mixture? <3
Rust is considered a mixture, not a pure substance, because its composition can vary. It is formed when iron reacts with oxygen and water.
Explanation:Rust is not a pure substance, it is a mixture. In scientific terms, rust is formally known as iron (III) oxide and is formed when iron reacts with oxygen and water. In this case, it behaves as a mixture because its composition can vary depending on the presence and relative abundance of other elements and compounds, such as water and other oxides.
Rust is a mixture rather than a pure substance. It is formed when iron reacts with oxygen in the presence of water or moisture, resulting in the formation of iron oxide, which is the reddish-brown substance we commonly refer to as rust. This mixture consists of iron oxide as well as other impurities, such as traces of water and other metals present in the environment.
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is NaCH an element ? why or why not?
Hydrogen peroxide is sold as a 3.0% (by mass) solution. The rest of the solution is water . How many grams of hydrogen peroxide are in 250 grams of this solution?
The question deals with percent by mass calculations. For a 3.0% by mass solution of hydrogen peroxide, there are 3 grams of hydrogen peroxide in every 100 grams of the solution. Therefore, a 250-gram solution would contain 7.5 grams of hydrogen peroxide.
Explanation:The solution of hydrogen peroxide is 3.0% by mass. This means that there are 3 grams of hydrogen peroxide in every 100 grams of solution. Therefore, in 250 grams of solution, the amount of hydrogen peroxide can be calculated by setting up a proportional equation:
(3 grams H2O2 / 100 grams solution) = X grams H2O2 / 250 grams solution
To solve for X, which represents the amount of hydrogen peroxide, cross multiply and divide:
(3 g H2O2 x 250 g solution) / 100 g solution = 7.5 g H2O2
So, there are 7.5 grams of hydrogen peroxide in a 250-gram solution.
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Which one is a true statement about endothermic reactions?
A) The reaction container always feels hot.
B) More heat is given off than is put into the reaction.
C) The reactant have less heat energy than the products.
D) Energy is absorbed making it feel colder.
Answer;
D) Energy is absorbed making it feel colder.
Explanation;
An endothermic reaction is a reaction in which heat energy is absorbed from the surroundings. In such a reaction the energy of the reactants is less than the energy of the products and therefore the enthalpy change is positive, greater than zero.
An endothermic reaction occurs when the energy used to break the bonds in the reactants is greater than the energy given out when bonds are formed in the products. This means that overall the reaction takes in energy, therefore there is a temperature decrease in the surroundings.
Answer:
I completely agree that it is D) Energy is absorbed making it feel colder!
is it convection conduction or radiation "air travels this way" please answer
humans protect themselves from natural disasters by all of the following expect ?
a. dams
b. sunscreen
c. building homes and shelters
d. levees
Technological design is a main focus in the field of _________.
A. biology B. chemistry C. mathematics D. engineering
An unknown solution has a pH of 2. How would you classify this solution?
A. Acidic
B. basic
C. Neutral
D. There is not enough information to answer this question.
Answer:
The answer is my opinion is A. Acidic.
Explanation:
It is lower than 7 (which is neutral) and lower than 8-14 (basic)
A neutral atom of beryllium (Be) has an average mass of 9 amu and 4 electrons. How many neutrons does it have?
13
9
5
4
To find the number of electrons, just subtract the amu and the atomic number (aka number of protons or electrons)...
so it is...
9-4=5 neutrons
Brainliest plz! :)
The number of neutrons in a neutral atom of beryllium is equal to 5. Therefore, option (B) is correct.
What is a neutral atom?A neutral atom can be defined as an atom in which the number of the negative charge is equal to the number of the positive charge. Therefore, the overall electric charge on the neutral atom is zero.
We can say that for a neutral atom, the number of protons in an atom is equal to the number of electrons in that atom. All elements arranged in the modern periodic table are in a neutral state.
The atomic mass or average mass of the atom is the sum of the number of protons and neutrons in the nucleus of that atom.
Given, the average mass of beryllium (Be) atom = 9 amu
Therefore, protons + neutrons = 9 in the one Be atom
The number of electrons in Be atom = 4
The number of neutrons in netural beryllium atom = 9 - 4 = 5
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Why is it important for the buret to be clean before using? How do you clean a buret
Is nail polish a pure substance or a mixture?
Nail polish is a mixture made up of solvents, polymers, colorants, and additives. It can be physically separated into its different components.
Explanation:Nail polish is a mixture, not a pure substance. It is made up of different components, such as solvents, polymers, colorants, and additives. These components are not chemically bonded together and can be separated from each other.
For example, if you leave a bottle of nail polish open, the solvents will evaporate, leaving behind a dried-up mixture. Additionally, if you mix two different colors of nail polish together, you will create a new mixture with a blend of the two colors. Therefore, nail polish is considered a mixture because it contains multiple substances that can be physically separated.
Nail polish is not a pure substance, but rather a mixture of several substances. A pure substance has a constant composition with fixed ratios of elements, but nail polish consists of a blend of different chemicals including solvents, film formers, resins, and plasticizers. Each of these components contributes to the characteristics of the final product, such as its ability to adhere to the nail, its durability, and its shine.
For instance, the film formers and resins create the hard coating on your nails that lasts for days, while the plasticizers provide flexibility so the polish doesn't chip or crack. Solvents are used to keep the other components in a liquid state so they can be easily applied to the nails. Once the polish is applied, the solvents evaporate, leaving behind the hard, colored film on the nail. This makes nail polish a mixture and not a pure substance.
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Nail polish is a homogeneous mixture, not a pure substance. It comprises many components like nitrocellulose, solvents, coloring agents, and plasticizers, each maintaining its own chemical identity within the mixture.
Explanation:Nail polish is not a pure substance but a homogeneous mixture. A homogeneous mixture is a combination of substances with a uniform composition. In the case of nail polish, it is a mixture of several components including but not limited to nitrocellulose, solvents, coloring agents, and plasticizers. Each of these components maintains its own chemical identity within the mixture; they are not chemically bonded into a new, larger chemical compound, which distinguishes mixtures from pure substances that consist of only one type of matter.
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After a hormone enters the bloodstream, it is transported throughout the body, but the hormone only affects certain cells. The reason only certain cells are affected is that the membranes of these cells have specific
Final answer:
Only certain cells are affected by hormones because these cells have specific receptor proteins that allow the hormone to bind and initiate a response. These receptors determine the cell's sensitivity to the hormone and can vary through up-regulation or down-regulation, adapting to hormone levels.
Explanation:
The reason only certain cells are affected by hormones is because only some cells have receptor proteins that can bind to a given hormone. These receptors are specific to a particular hormone and allow it to have an effect when it binds to them.
The hormone will travel throughout the bloodstream until it finds a cell with the correct receptor and binds to it, which initiates various responses depending on the type of hormone, such as a steroid hormone or a non-steroid hormone.
Hormones, acting as messengers, are crucial in regulating physiological processes. They play a significant role in human reproduction, development, metabolism, and maintaining homeostasis, among other functions.
The presence and quantity of hormone receptors determine which cells will respond to a given hormone, thus determining the sensitivity of the cell to the hormone. Cell sensitivity to hormones can change through processes like up-regulation and down-regulation, which adapt the number of receptors available in response to hormonal levels.
Examine the false statement.
The alkali earth metals have five valence electrons.
Select the rewording of the statement that is true.
The alkali earth metals have one valence electron.
The alkali earth metals have two valence electrons.
The halogens have five valence electrons.
The alkali metals have five valence electrons.
Answer:
The alkali earth metals have one valence electron.
Explanation:
Alkali earth metals are elements that constitute Group I in the periodic table. These include: lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs) and francium (Fr).
The alkali earth metals are characterised by a outer or valence electron configuration of ns¹.
Li = 2s¹, Na = 3s¹, K = 4s¹, Rb = 5s¹, Cs = 6s¹
Therefore, in their outermost or valence shell these elements have only one electron.
Hence the given statement: that the alkali earth metals have 5 valence electrons is false. Instead it should be reworded as:
The alkali earth metals have one valence electron.
The alkali earth metals, located in the second group of the periodic table, have two valence electrons, not five. So, the true rewording of the given statement should be 'The alkali earth metals have two valence electrons'.
Explanation:The statement that 'The alkali earth metals have five valence electrons' is incorrect. The alkali earth metals, which occupy the second group of the periodic table, actually have two valence electrons. Therefore, the correct rewording of the statement would be 'The alkali earth metals have two valence electrons'.
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Many older windows have only a single pane of glass. Why do these windows not insulate well?
A. Glass conducts heat better than air.
B. Glass conducts cold better than air.
C. Air conducts heat better than glass.
D. Air conducts cold better than glass.
Enter the net ionic equation, including phases, for the reaction of AgNO3(aq) with K2SO4(aq). Solubility Rules are found here.
what element has two electrons in its 4d sub level?
Answer is: zirconium (Zr).
Atomic number of zirconium (Zr) is 40, which means it has 40 protons and 40 electrons.
Electron configuration of zirconium atom:
₄₀Zr 1s²2s²2p⁶3s²3p⁶3d¹⁰4s²4p⁶4d²5s².
Zirconium has four valence electrons, it is in group 4 and period 5.
Zirconium is a lustrous, grey-white, strong transition metal.
An apple has a mass of 297 grams. How many kilograms is this? (Note: You can use the information in the table below to make a conversion factor.)
Answer: 0.297 grams.
Explanation: the conversion factor between kilograms and grams is:
1 kg=1000 g
applying this factor to the given mass of an apple, we have:
[tex]297 grams *\frac{1 kg}{1000 grams}[/tex]
as we can see, we just have to divide by 100 so:
297 grams= 0.297 kg.
The apple has a mass of 0.297 kilograms
HOW TO CONVERT GRAMS TO KILOGRAMS:
Grams and kilograms are both units of measuring mass, however, they are not the same. The conversion factor of grams and kilograms is as follows:1 kilogram = 1000 grams
According to this question, an apple has a mass of 297 grams. This means that:If 1 kilogram = 1000 grams
297 grams = 297 ÷ 1000
= 0.297 kilograms
Therefore, the apple has a mass of 0.297 kg.
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Describe the preparation of 2.00 L of 0.100 M glycine buffer, pH 9.0, from glycine and 1.00 M NaOH.
Caleb wants to find out which type of floor material is best for bouncing tennis balls the highest. Which statement best describes the process he should use?
He should use technological design because he will need to make materials.
He should use scientific investigation because he will need to do an experiment.
He should use technological design because he will need to conduct background research.
He should use scientific investigation because he will need to design a prototype.
Answer:
B. He should use scientific investigation because he will need to do an experiment.
How do the cells of a multicellular organism differ from those of a unicellular organism
Answer:
The cells of unicellular organism is not equipped for different function which means that it do not have different types of cells differentiated into different types performing different functions.
They are made of single cells that perform all the essential functions necessary for survival of organism.
Whereas, a multicellular organism have different types of cells that are employed for different functions.
Example:The hepatocytes are equipped for filtering blood and waste removal. The red blood cells are equipped to transport oxygen to various parts of the body.
How does an individual figure the total force exerted on an object by two forces acting in opposite directions?
A. Add the two forces together.
B. Subtract the smaller force from the larger force.
C. Multiply the larger force by the smaller force.
D. Divide the smaller force by the larger force.
Which type of reaction has the general formula of AB + CD → AD + CB?
The _______ is the layer of the atmosphere nearest to Earths surface
Julia wants to find out which color fabric will heat up the fastest when put under a direct light.
So, she places pieces of red, white, and green fabrics outside in the sunlight. Then, she places pieces of black, yellow, and blue fabric inside under a bright lamp. Finally, she measures the temperature of all the fabric samples every 5 minutes.
Will Julia's results be valid?
Answer:
no to many variables
Explanation:
When might a technique called water displacement be used?
Acids will corrode most _____.
bases
liquids
metals
gases
Acids will corrode most metal.
I hope this helped if you have anymore question I'll be glad to help ;)
How will the following system react when an increase in pressure occurs? Note: all species are gases. N2O4 <--> 2NO2 Question 9 options:
a. More N2O4 is produced.
b. There is no way to predict how the increase in pressure will affect this system without more information.
c.No change occurs.
d.More NO2 is produced.
a is incorrect just took the test
a student determined in the laboratory that the percent by mass of water in cus04 5h20 is 38.0% if the accepted value is 40% what is the percent of error
Final answer:
The percent of error is calculated using the formula: Percent error = (Experimental Value - Accepted Value) / Accepted Value * 100%. In this case, the percent of error is -5%.
Explanation:
The percent of error can be calculated using the formula:
Percent error = (Experimental Value - Accepted Value) / Accepted Value * 100%
Given that the experimental value for the percent by mass of water in CuSO4 • 5H2O is 38.0% and the accepted value is 40%, the percent of error can be calculated as:
((38.0 - 40) / 40) * 100% = -5%
Therefore, the percent of error is -5%.
The percent error in the student's measurement of the percent by mass of water in CuSO4·5H2O is 5.0%. This is calculated by using the formula for percent error, which yields a percent error of 5.0%.
Explanation:The student determined that the percent by mass of water in CuSO4·5H2O is 38.0%, but the accepted value is 40%.
To calculate the percent error, we use the formula:
Percent Error = (|experimental value - accepted value| / accepted value) × 100%
Substituting the given values:
Percent Error = (|38.0% - 40.0%| / 40.0%) × 100%
Percent Error = (2.0% / 40.0%) × 100% = 5.0%
Thus, the percent error in the student's measurement is 5.0%.
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
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