How many moles are in a sample of 2.39 x 10^23 atoms of sodium (Na)
Answer:
The answer is 0.4 molesExplanation:
To find the number of moles in a substance given it's number of entities we use the formula
[tex]n = \frac{N}{L} \\ [/tex]
where n is the number of moles
N is the number of entities
L is the Avogadro's constant which is
6.02 × 10²³ entities
From the question we have
[tex]n = \frac{2.39 \times {10}^{23} }{6.02 \times {10}^{23} } \\ = 0.39700996...[/tex]
We have the final answer as
0.4 molesHope this helps you
Volcanic belts form along
a.
islands in the Pacific Ocean.
b.
North American mountain ranges.
c.
the boundaries of Earth’s plates.
d.
the coast of Antarctica.
Please select the best answer from the choices provided
ANSWER ASAP PLEASE!!
What determines how many of each ion is required for an ionic compounds?
please do not look up on google!!!!
Each ion has a single charge, one positive and one negative, so we need only one ion of each to balance the overall charge. When writing the ionic formula, we follow two additional conventions: (1) write the formula for the cation first and the formula for the anion next, but (2) do not write the charges on the ions.
How does the valence electron configuration (entire last energy level configuration) relate to the group number on the Periodic Table? Use the shorthand notation in your discussion.
Answer:
The valence electron configuration determines the group to which an element belongs to.
Explanation:
The valence electron configuration of an atom of an element refers to the number of electrons in that atoms outermost shell.
The valence electron configuration is related to the group number of an element in that the number of electrons in the valence shell of an atom of an element determines the group to which an element belongs to. For example, all elements having one valence electron belong to group IA of the periodic table. Similarly, all elements having seven valence electrons belong to group VIIA of the periodic table.
This is because, since the reactivity of an element is related to its ability to either gain or lose a certain number of electrons in its valence shell, elements having same number of valence electrons have similar chemical properties.
What suprising result is explained using this model
Answer:
B. A few positive particles bounced back because they were pushed away from the positive center.
Explanation:
The result of the experiment conducted by Rutherford shows that a few positive particles bounced back because they were pushed away from the positive center.
This is the central theme of Rutherford's experiment on a thin gold foil.
In 1911, Rutherford performed the gold foil experiment that gave the modeling of the atomic structure a great boost. He bombarded a thin gold foil with alpha particles. He discovered that most of the alpha particles passed through the foil while a few of them were deflected back. This led him to postulate that an atom has a small positively charged center where nearly all the mass is concentrated.Which describes the elements in a given group of the periodic table?
They decrease in atomic mass as you go down the column.
They increase sequentially in atomic number from top to bottom.
They are in the same family, with similar characteristics.
Their properties change according to a pattern as you go down the column.
Answer:
They are in the same family, with similar characteristics.
Explanation:
The elements in a given group of the periodic table are in the same family and with similar characteristics.
Vertical columns on the periodic table are referred to as a group or family. Elements having the same number of electrons in the outermost shell of their atoms are placed one another in vertical columns. Each resulting vertical column is a group or family. Elements in the same group exhibit similar chemical properties because of the same number of electrons in their atoms' valence shells.
How many atoms are in the following formula?
3Al2O3
Answer:
15 atoms total
Explanation:
2 Al atoms + 3 O atoms = 5 Al2O3 atoms
5 Al2O3 atoms * 3 = 15
another way to do it is:
2 Al atoms * 3 = 6 Al atoms
3 O atoms * 3 = 9 O atoms
6+9 =15 atoms total
The number of atoms in the given 3Al₂O₃ is 15 atoms.
What are atoms?Atoms are the smallest unit of every matter. It contains charged particles present inside the atoms. They are electrons, protons, and neutrons. Atoms are of four types, description, isotopes, radioactive, and ions.
These atoms are the ions, that are charged, and the charged ions make bonds with each other to form compounds. Aluminum oxide is a compound that is formed by combining aluminum and oxygen atoms.
The compound is 3Al₂O₃
This means there are three moles of aluminum, and three moles of oxygen.
2 Al atoms + 3 O atoms = 5 Al₂O₃ atoms
5 Al₂O₃ atoms x 3 = 15
The elaborative way is:
2 Al atoms x 3 = 6 Al atoms
3 O atoms x 3 = 9 O atoms
6 + 9 =15 atoms total
Thus, the number of atoms is 15 atoms.
To learn more about atoms, refer to the link:
https://brainly.com/question/25620560
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32 N of Force. 37 N force. How strong is the net force and in which direction?
challenges we will face terraforming Mars
Would love some help pleaseee. and please at least read the question instead of skipping it please.
Measuring tools can have errors. Errors lead to ___________________ results and _______________ conclusions. To calculate the difference of the accepted value and the experimental value, scientists use this formula:
percent error = (experimental value − ) × 100. accepted value
Minimizing Bias
People show bias when they want everyone to accept their results. Bias can arise for many reasons:
• Companies show bias when they depict only the research details that are in the best interest of their ____________.
• Scientists may be biased toward their _____________ and modify results suit their needs.
• Scientists may also show to bias get their research published in ______________ ______________.
Such biases often lead to _______________ facts. An important part of scientific thinking is identifying biases and taking the necessary steps to minimize them.
For results to be considered scientifically accurate, any scientist, regardless of his or her own bias, should be able to replicate the experiment and get the same results.
Summary
Think of some studies you’ve heard about. How can you tell whether the studies were well-designed and scientifically accurate or had biases?
Answer: this looks like your homework
Explanation:if you want help you are going to have to ask a specific question instead of giving people your homework.
Answer:
Honestly I would search this up maybe there might be a pdf with the answers. Sorry chemistry isn't my thing:(
Explanation:
What is force and motion
Answer:
In physics, a force is any interaction that, when unopposed, will change the motion of an object. A force can cause an object with mass to change its velocity (which includes beginning moving from a state of rest), i.e., to accelerate. Force can also be described intuitively as a push or a pull.
lol
What is the mass of an object with a density of 5.7 g/cm^3 and a volume of 48
cm^3? *
Answer:
273.6 g
Explanation:
mass =(density)(volume)
mass=(5.7g/cm^3 )(48 cm^3)
cancel out your cm^3 and your are left with grams
multiply (5.7g)(48)=273.6 g
The mass of an object with a density of 5.7 g/cm³ and a volume of 48 cm³ is 273.6 grams.
What is density?Density is defined as the degree to which a material is packed together.
It is also defined as a mass per unit volume of the substance.
Its SI unit is kilogram per cubic meter or gram per meter.
Density can be expressed as
Density = mass / volume
Mass = density x volume
As given, Density = 5.7 g/cm³
Volume = 48 cm³
So, Mass = 5.7 g/cm³ x 48 cm³
= 273.6 grams
Thus, the mass of an object with a density of 5.7 g/cm³ and a volume of 48 cm³ is 273.6 grams.
To learn more about density, refer to the link below:
https://brainly.com/question/15164682
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choose the letter that best describes the behavior of a substance during a phase change:
/A/ neither absorbs or releases energy
/B/ always absorbs energy
/C/ always releases energy
/D/ either absorbs or releases energy
Answer:
/D/ either absorbs or releases energy
Explanation:
During a phase change energy is either absorbed or released.
A phase change is a reversible process which occurs when a substance changes is its state from one form to another.
Phase changes are used to delineate physical changes.
A phase diagram provides a graphic representation of the change. The diagram can be 2 dimensional or 3 dimensional.Which types of matter are made of atoms
a. Mixtures
b. Elements
C. Compounds
D. All of the above
Answer:
D all above yes I think it's all above
Answer: D
Explanation: All of the above.
Plz mark brainliest:)
Does the use of lithium cause human health problems?
Answer:
Yes
Explanation:
Lithium can cause nausea, diarrhea, dizziness, change in heart rhythm, muscle weakness, fatigue, and a dazed feeling
Continued use of Lithium could mean fine tremor, frequent urination, and thirst
Source: Webmd.com
What is a system?
A. An isolated piece of the world
OB. A liquid in which reactions take place
O C. A piece of scientific equipment
O D. A technique for recording data
Answer:
D. a technique of recording data
Need help ASAP please
Answer:Melting can create steam, kind of like a nukeular plant exept no nukulear rods
stages of mitosis in order
Answer:
nucleus formed
prophase
metaphase
anaphase
telophase and cytokinesis
You are conducting an experiment with two very reactive substances. One will react with oxygen (O) and other substances in the air, and the other will react to metal in a container. What type of environment can you seal them in so they only react with each other?
Answer:
seal them in a glass container in an atmosphere of argon (Ar) gas
Explanation:
What is meant by a solute-give an exmple.
What is meant by a solvent - give an exemple
what is meant by a solution -give an exmple
what do the following symbole mean s,l,g and aq
what is the difference between filtration and crystallisation
Answer:
A solute is a substance that dissolves in a solvent to for a solution.Example; Sugar.
A solvent is a substance that dissolves a solute to form a solution.Example ;water.
A solution is a uniform mixture of a solute and a solvent.
aq means aqueous
In fiteration the residues are called filtrates but in crystalization the residues are called crystals .
Which of the following is the correct model of C7H16?
A.
B.
C.
D.
Answer:
D
Explanation:
Option D gives the correct model of C7H16. From the option, one will discover that the model has 7 carbons in the backbone. If you count the attached hydrogen, you will discover that the hydrogen is 16 in total.
This model or skeletal structure of this element represents heptane. Heptane or n-heptane is known to be a straight-chain compound and an alkane. It's chemical formula can also be written as: H₃C(CH₂)₅CH₃ or C₇H₁₆.
This compound is known to be one of the main components of gasoline. It is known to be a volatile organic compound and a clear and colorless liquids with a petroleum-like odor.
Answer: D
Explanation: Just took the test
What is Arsenic cost per unit?
Answer:
arsenic costs $320 per 100g
Explanation:
Michelle learns in science class that simple machines such as an inclined plane can change the amount of force needed to lift heavy objects. She decides to test this with an experiment.
Michelle chooses a 10 kg weight. She sets up a ramp made of smooth metal that makes an angle θ with the floor. She attaches a spring scale to the weight and the top of the ramp in order to hold the weight in place. She records the force from the spring scale, then changes θ and records it again. She repeats this several times.
In this experiment, what is the dependent variable?
A.
the mass of the weight
B.
the angle θ between the ramp and the ground
C.
the amount of force on the spring scale
D.
the material the ramp is made of
Be fast please
What explains the structure of metals and delocalized electrons?
A. the unit cell model
B. the geometric shape model
C. the covalent bond model
D. the electron sea model
25 cm of liquid 'A' and 20 cm of liquid
'B' are mixed at 25°C and the volume of
solution was measured to be 44.8 cm3
then correct reaction is
(A) A Hmix = 0, solution shows
ideal
Answer:
The correct option is;
(B) [tex]\Delta H_{mix} < 0[/tex], solution shows negative deviation
Explanation:
The given parameters are;
The available volume of liquid A = 25 cm³
The available volume of liquid B = 20 cm³
The volume of the solution (mixture) = 44.8 cm³
Therefore, we have;
[tex]\Delta _{mix} V < 0[/tex]
Which is one of the prerequisite for the formation of negative deviation
When a non-ideal solution shows negative deviation according to Raoult's Law, we have;
[tex]\Delta _{mix} H < 0[/tex], we have more heat released due to new molecular interactions.
If the density of a substance is 2.18 g/mL, how would you find the density given that the mass is 0.987 kg and the volume is 4.52 x 102 mL?
Answer:
Explanation:
Convert mass in gms .. 987 gms
Density = mass/ volume
= 987/4.52 x102
= 2.18 g/mL
When many earthquakes are studied, there is another common pattern that emerges: a "Shadow Zone". This is an area, for any earthquake, on the Earth where direct S-waves don't arrive at all and P waves are refracted. What do you think causes these P waves to be refracted? *
Answer:
Sudden decrease in the velocity at the boundary.
Explanation:
The shadow zone is the zone of the earth from angular distances of 104° to 140° from a known earthquake that does not directly receive any P waves. Now, this shadow zone occurs as a result of S waves getting stopped completely by the liquid core and the P waves being refracted by the liquid core.
From earlier seismic discoveries, this boundary which is the shadow zone that does not directly receive any P-waves was found to be due to the fact that the P-waves were refracted inwards as a result of the sudden decrease in velocity at the boundary.
Pioneer species like Lichens and Mosses inhabit an area after a major disturbance, such as a volcanic eruption. Over time, other species are found in the disturbed areas, and the number of pioneer species decreases. Why does the number of pioneer species get less?
Answer:
The number of pioneer species get less as the area has more soil to support complex plants and the competition decreases the role of pioneer species.
Explanation:
Pioneer species like Lichens and Mosses inhabit an area after a major disturbance, such as a volcanic eruption. However, with time the number of pioneer species decreases.
The number of pioneer species get less as the area has more soil to support complex plants and the competition decreases the role of pioneer species.
What is the decomposition of 2LiCIO3
Why are biopharmaceuticals in high demand?
Answer:
the market is largely driven by the growing population, increasing burden of chronic disease, and rising inclination toward targeted therapy.
Explanation:
also, the huge demand of biopharmaceutical is facilitated by an accelerating focus in research and related investment.