6. There are three isotopes of silicon. They have mass numbers of 28, 29 and 30. The average atomic mass of silicon is 28.086amu. What does this say about the relative abundances of the three isotopes?
Answer:
That means that the isotope that has a mass number of 28 is probably the most abundant. This is because your average atomic mass is 28.086 amu, which is closest to 28.
Formula used to calculate average atomic mass follows:
average atomic mass=(atomic mass of an isotope)*(fractional abundance)
we are given=
Three isotopes of Silicon, which are Si-28, Si-29 and Si-30.
Average atomic mass of silicon = 28.086 amu
As, the average atomic mass of silicon is closer to the mass of Si-28 isotope. This means that the relative abundance of this isotope is the highest as compared to the other two isotopes.
Percentage abundance of Si-28 isotope = 92.2%
Percentage abundance of Si-29 isotope = 4.7 %
Percentage abundance of Si-30 isotope = 3.1%
Hence, the abundance of Si-28 isotope is the highest as compared to the other isotopes.
3. How many moles are in 1.49 x 1023 molecules of iodine?
Answer:
The answer is 0.25 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{1.49 \times {10}^{23} }{6.02 \times {10}^{23} } = \frac{1.49}{6.02} \\ = 0.247508305...[/tex]
We have the final answer as
0.25 molesHope this helps you
Each atom of an element has the following electron configuration.
1s22s22p63s23p64s23d104p65s24d105p5
What is the name of the element?
Which option is an Ionic Compound
A.LiCl
B.CO
C.No2
D.So3
Answer:
LiCI
Explanation:
CO and No2 are both covalent compounds and it was a 50 50 and I guessed the right answer.
The one that is an ionic compound is LiCl. The correct option is A.
What are ionic compounds?
Ionic compounds are those compounds that have one negative and one positive charge molecule. When this negative and positive charge joins together, the compound becomes neutral. Electrostatic force joins these elements.
LiCl is a salt that is formed by the joining of lithium with chloride. Lithium is positively charged and chlorine is negatively charged. One identity of this compound is that it is a neutral salt, so it can be identified as an ionic compound. When they disjoint, they form a crystal-like structure.
An example of an ionic compound is sodium chloride, in which sodium is positive and chloride is negative.
Therefore, the correct option is A. LiCl.
To learn more about ionic compounds, refer to the link:
https://brainly.com/question/9167977
#SPJ2
A chemist titrates 100.0 mL of a 0.3065 M aniline (C6H5NH2) solution with 0.5774 solution at 25 . Calculate the pH at equivalence. The of aniline is .
Answer:
4.91
Explanation:
From the given information:
The millimoles of aniline = 100* 0.3065 = 30.65
30.65 millimoles HNO3 must be added to reach the equivalence point.
30.65 = V x 0.5774
V = 30.65/0.5774
V = 53.08 mL HNO3 must be added
Thus, total volume = 53.08 + 100 = 153.08 mL
[salt] = 30.65 / 153.08 = 0.20022 M
At equivalence point :
pOH = 1/2 [pKw + pKb + logC]
pOH = 1/2 [14 + 4.87 + log 0.20022 ]
pOH =9.086
pH = 14 - 9.086
pH = 4.914
pH ≅ 4.91 to 2 decimal places.
True or false. (Pls help)
Answer:
1.) False?
2.) true. sorry english not my first language
what is the ionic compound formula sodium nitride?
Answer:
In ionic compounds, the charges of constituent ions must balance. This can be achieved by having three sodium ions per nitride ion. Therefore, the formula of sodium nitride is Na3N
Explanation:
Answer:
the charges of constituent ions must balance. This can be achieved by having three sodium ions per nitride ion. Therefore, the formula of sodium nitride is Na3N
Explanation:
different type of flatbread
What is the molar mass of H2SO4?
Answer:
98.08g/mol is your answer
Explanation:
hope this helps
Which option will increase the rate of reaction?
Answer:
Explanation:
there's no options that you put but usually if you add more of the reactant the rate will increase, adding a catalyst will increase the rate, and increasing the temperature if it's endothermic
which best explains why a scientist would share these details in a conference?
a it tells the audience if the results support or contradict the hypothesis
b it tells the peers if the study is supported by mathematical models
c it informs the peers of the results are supported by other scientists
d it informs the audience if the study included controlled tests
The question is incomplete, the complete question is; During a conference presentation, a scientist described the materials that she used and how she performed her experiments.
Which best explains why a scientist would share these details in a conference?
It tells the audience if the results support or contradict the hypothesis.
It tells the peers if the study is supported by mathematical models.
It informs the peers if the results are supported by other scientists.
It informs the audience if the study included controlled tests.
Answer:
It informs the audience if the study included controlled tests.
Explanation:
Usually, scientific conferences involve presentation of papers by scientists. These paper presentations are actually the sharing of details of the scientific research carried out by other scientists.
Presenting the materials and methods section of the a research project to a scientific conference informs the audience if the study included controlled tests.
The inclusion of controlled tests in a scientific study enhances the validity of the results obtained in the study.
How do you calculate wavelength and frequency?
Answer:
Wavelength can be calculated using the following formula: wavelength = wave velocity/frequency. Wavelength usually is expressed in units of meters. The symbol for wavelength is the Greek lambda λ, so λ = v/f.
Explanation:
Just a formula that's commonly used in biology.
Tubbo or TommyInnit? Choose wisely.
Answer:
Tubbo
Explanation:
more informational
Mention any three ways of making salt. (please help me Asap)
What are the parts of an electron configuration?
Answer:
Explanation:
electronic confirmation=1s^2,2S^2,2P^6,3S^2
atomic no.is 12 therefore :- this is magnesium
Period=3
Block=s-block
Group=II A
NEED HELP ASAP!!!!! PLEASE HELP!!!!! NEED HELP ASAP!!!!!
Directions: Name the covalent compound created.
EXAMPLE- Sr3P2= Tristrontium diphosphide
CH4 =
B2Si =
N2O5 =
CO2 =
Answer:
CH4 - Methane
B2Si - Diboron monosilicide
N2O5 - Dinitrogen pentoxide
CO2 - Carbon dioxide
Explanation:
When it comes to naming covalent compounds, there are several rules.
The name is derived based on the formula. For example, N2O5. The first element is nitrogen. To the name of the element, you add the prefix that tells us how many of its atoms are in the compound. In this case, there are two atoms, which means that the prefix will be di- (dinitrogen). The second element is oxygen. You are supposed to take only the root of the second element's name and then add the prefix denoting the number of its atoms and the suffix -ide (pentoxide). This is how we'll get dinitrogen pentoxide.
The only exception is methane (CH4), which is an organic compound. Organic compounds are named using the IUPAC nomenclature.
How would you ask a girl out. I know that I can use my voice, but I don’t know what to say.
Answer:
Just go out there and be yourself brother!
Explanation:
If she doesn't like you, she doesn't like the real you, therefore you don't deserve her! lol
Which of the choices is an example of an element?
O CO
O Co
O C2H2O2
O CO2
Answer:
Co(cobalt) is the answer
Explanation:
Cobalt is a chemical element with the symbol Co and atomic number 27. Like nickel, cobalt is found in the Earth's crust only in chemically combined form, save for small deposits found in alloys of natural meteoric iron. The free element, produced by reductive smelting, is a hard, lustrous, silver-gray metal.
:answer question number 10
Answer:
the last one
Explanation:
I'm pretty sure
Answer:
Particles on each are constantly moving (the last one)
Please answer it!! Would appreciate it!
[tex] \sf \: Answer \: 8 \: :[/tex]
→ During the formation of a chemical bond, heat is released.
[tex] \sf \: Answer \: 9 \: :[/tex]
→ Solution that contains all the solute it can hold at a given temperature is saturated.
[tex] \sf \: Answer \: 10\: :[/tex]
→ No. of neutrons present in Bromine are 44
How much energy would be needed to raise the temperature of a 5kg block of concrete by 10°C?
Answer:
5 x 10 x 3200 = 170 000J or 170kJ
Explanation:
i searched it lol
The energy needed to raise the temperature of a 5 kg block of concrete by 10° C is 170 000J or 170kJ.
What is energy?Energy is defined as a quantitative property that is transferred to a body or to a physical system. It can also be defined as capacity of doing work.
There are basically five forms of energy
Electrical energyChemical energyMechanical energyThermal energyNuclear energyHeat energy = mass x heat capacity x raise in temperature
= 5 x 3200 x 10
= 170000 J or 170 kJ
Thus, the energy needed to raise the temperature of a 5 kg block of concrete by 10° C is 170 000J or 170kJ.
To learn more about energy, refer to the link below:
https://brainly.com/question/1932868
#SPJ2
With a partner, look at the stone bricks used to build this building and think about how they changed over time. What caused them to change? Do you think these changes occurred quickly or slowly? Explain.
Answer:
Chemical WeatheringSlowlyExplanation:
Building bricks deteriorate overtime due to chemical weathering from moisture constantly in contact with it overtime, as well temperature changes. Their topmost layers leach after continuous attack, and are eroded. thereby causing them to break away most times.
This cycle takes place overtime and is not a quick action.
I hope this is easy to understand.
Chemical bonding is the combining of elementa to form
-energy levels
-atoms
-electrons
-compounds
BRAINLIEST! Please help me answer the following questions:
1) How do you find the valency of an element?
2) How do you determine if an element is nuetral/an isotope/ or an ion?
If you could help with 1 or both questions I would really appreciate it :)
Explanation:
1) from the periodic table for example if u looking for K it is from the group 1A so the valancey = +1 that is mean it loses one electron to reach a stable state. and this applied for the 1A , 2A, 3A groups.
if u looking for N it is from group 5A so its valency is -3
so it gain 3 electrons to reach a stable state to complete its orbital to 8 electrons. this applied to 5A, 6A,7A
for the transition metals and simimetals other rules.
2) neutral if the element does not hold any charge like
H2, O2, N2, Fe, Au, Cu ...
isotope : if the 2 elements have same symbol and atomic number but they differ in the mass number because the have different numbers of neutrons.
if the element is charged then it is considered as an ion ex: Fe2+ then it is iron cation ( +ion)
F- then it is fluoride anion (-ion)
if u have any doubt just writ a comment ( ;
Which statement describes how chemical formulas, such as H2O, represent compounds?
They show the types of molecules that make up an atom.
They show the elements that make up a compound.
They show the three-dimensional shape of a molecule.
They show the types of bonds that exist between elements.
Answer: B. They show the elements that make up a compound
Explanation:
Answer:
B
Explanation:
Someone help me please i’ll give brainly
Answer:
Condensation
Explanation:
Which of the following is an example of Newton’s 2nd Law? A. A bowling ball requires more force to roll than a tennis ball B. Sitting in a chair C. A rocket blasting off D. All of the above
Answer:
The answer is A.
Explanation:
how are fireworks manufactured and produced
Answer:
1. rolled paper tubes filled with black powder (also called gunpowder), are made.
2. Sometimes they are filled with flash paper and a fuse.
3. When the fuse of a firecracker gets lit, the fire burns along the fuse.
4. Then it eventually reaches the powder, and explodes.
Explanation:
A student investigated the time taken for amylase to breakdown a 10% starch solution into glucose at
37°C. The student repeated the investigation five times
Figure 11 shows the results
time taken for amylase to produce glucose (s)
Test 4
120
125
110
115
Figure 11
() Calculate the rate of amylase enzyme activity for the 10% starch solution.
Answer:
Phenolphthalein is an indicator. It is pink in alkaline solutions and turns colourless as the pH decreases.
It can be used to measure the activity of the enzyme lipase on the breakdown of lipids.
Samples of milk containing phenolphthalein were incubated with lipase at different temperatures.
The time taken for the phenolphthalein to turn colourless was recorded and used to calculate the rate of enzyme activity.
Figure 10 shows these results.
Picture
(a) (i) Explain why phenolphthalein turns colourless when lipase breaks down the lipids in milk. (2)
(ii) Describe the effect of temperature on the activity of lipase, as shown in Figure 10. (2)
(iii) Explain why the activity of lipase changes above a temperature of 40°C. (2)
(b) A student investigated the time taken for amylase to breakdown a 10% starch solution into glucose at 37°C. The student repeated the investigation five times.
helpp!! only answer if u know or think u know!
ILL MARK U BRAINLIEST
this is science btwww
Answer:
answer on what no file attached
Explanation:
Answer:
Igneous rocks form when magma (molten rock) cools and crystallizes, either at volcanoes on the surface of the Earth or while the melted rock is still inside the crust. All magma develops underground, in the lower crust or upper mantle, because of the intense heat there. first question Natural non-living things: They are found in nature and are not made by man. Examples: Sun, moon, stars, sky, clouds, rocks, mountains and many more. Man-made non-living things: They are made by man. Examples: Toys, chairs, tables, beds, houses, buildings, trains and many more. second question Metamorphic rocks form from heat and pressure changing the original or parent rock into a completely new rock. The parent rock can be either sedimentary, igneous, or even another metamorphic rock. The word "metamorphic" comes from Greek and means "To Change Form". third question. Sedimentary. fourth question and sorry I can't answer the last :(
Explanation: