Answer:
C. Protect them from predators because their calcium carbonate exterior allows them to withstand an attack from their predators in their specific environment.
Explanation:
They build layers to protect themselves from predators. Plus, I've seen this question and got it right.
Which best describes the total mass of substances before and after a
combustion reaction?
A. The mass is the same because atoms are not created or
destroyed.
B. The mass is greater after the reaction because the number of
atoms increases.
C. The mass is the same because the molecules do not change.
D. The mass is less after the reaction because gases are produced.
Answer:
B. The mass is greater after the reaction because the number of
atoms increases.
Carbon-14 has a half-life of 5,730 years. It is used in "carbon dating" to determine the age of once living organisms. How much of a 144 gram sample of C-14 will remain after 17,190 years have past.
Answer:
18 grams
Explanation:
Because 17,190 yrs divided by the amount of years it takes for a half-life to occur is 3. So 3 half life’s happen, so you divide 144/2 once, equaling 72. You divide 72/2 again (another half-life) and you get 36. You then calculate the third half life by dividing 36/2 which equals 18 grams.
Answer:
5730
Explanation:
Answer to Founders Education:)
What is [H⁺] in a 0.330 M solution of acrylic acid, CH₂CHCOOH (Ka = 3.16 × 10⁻⁵)?
Answer:
[H⁺] = 3.23x10⁻³ M
Explanation:
For a weak monoprotic acid, such as acrylic acid, we can calculate [H⁺] using the following formula if the solution concentration is significantly higher than the Ka:
[H⁺] = √(C * Ka)Where C is the weak acid concentration.
We input the data:
[H⁺] = [tex]\sqrt{0.330 M * 3.16x10^{-5}}[/tex]And solve for [H⁺]:
[H⁺] = 3.23x10⁻³ Mhelp i will mark brainliest
Answer:
Image A
Explanation:
The hemisphere experiences summer when it is tilted towards the sun. Image a has the northern hemisphere tilted towards the sun.
Answer:
image A
Explanation:
this is because the sun is hitting earth at a steep angle
A cylindrical rod of copper (E = 110 GPa) having a yield strength of 240 MPa is to be subjected
to a load of 6660 N. If the length of the rod is 380 mm, what must be the diameter to allow an
elongation of 0.50 mm?
Answer:
required diameter is 7.65 mm
Explanation:
Given the data in the question;
F = 6660 N
l₀ = 380 mm = 0.38 m
E = 110 GPa = 110 × 10⁹ N/m²
Δl = 0.50 mm = 0.0005 m
So, lets assume the deformation is elastic;
d₀ = √( [4l₀F] / [πEΔl] )
we substitute
d₀ = √( [4 × 0.38 × 6660] / [π × (110 × 10⁹) × 0.0005]] )
d₀ = √( 10123.2 / 172787595.947 )
d₀ = √( 5.85875 × 10⁻⁵ )
d₀ = 0.007654 m
d₀ = ( 0.007654 × 1000 )mm
d₀ = 7.65 mm
Therefore, required diameter is 7.65 mm
One method of increasing the chances of particles colliding during a reaction is to...
1)decrease temperature
2) decrease concentration
3)increasing concentration
4)use a catalyst
Answer:
3
Explanation:
Increasing concentration
Solid AgCl (Ksp = 1.8 X 10-10) is placed in a beaker of water. After a period of time, the Ag+ concentration is measured and found to be 2.5 X 10-7 M.
a) What is the concentration of Cl-?
b) Has the system reached equilibrium?
c) Will more AgCl dissolve?
Explanation:
a)
[tex]k _{sp} = [Ag {}^{ + } ][Cl {}^{ - } ] \\ but \: [Ag {}^{ + } ] = [Cl {}^{ - } ] \\ k _{sp} = [Ag {}^{ + } ] {}^{2} \\ [Ag {}^{ + } ] = \sqrt{k _{sp}} \\ = \sqrt{1.8 \times {10}^{ - 10} } \\ = 1.34 \times {10}^{ - 5} mol {dm}^{ - 3} [/tex]
b)
It has not reached equilibrium because the silver concentration is not yet equal to the value of Ksp.
c)
Yes it will dissolve in order to establish the equilibrium.
Compute the number of electrons that each lead atom donates, on average, to a bulk piece of lead metal. Room temperature data for lead: The conductivity of lead is 4.90 × 104 1/(Ω·m) The electron mobility of lead is 2.3 cm2/(V·s) The mass density of lead is 11.4 g/cm3 The atomic weight of lead is 207 g/mol
Answer:
4 electrons/atom
Explanation:
The conductivity of the lead σ = neμ where n = electron density, e = electron charge = 1.602 × 10⁻¹⁹ C and μ = electron mobility of lead = 2.3 cm²/(V·s) = 2.3 × 10⁻⁴ m²/(V.s)
Making n subject of the formula, we have
n = σ/eμ
Since σ = 4.90 × 10⁶ (Ω·m)⁻¹
Substituting the values of the variables into the equation, we have
n = σ/eμ
n = 4.90 × 10⁶ (Ω·m)⁻¹/(1.602 × 10⁻¹⁹ C × 2.3 × 10⁻⁴ m²/(V.s))
n = 4.90 × 10⁶ (Ω·m)⁻¹/(3.6846 × 10⁻²³ Cm²/(V.s))
n = 1.33 × 10²⁹ electrons/m³
We now find the number of moles of lead present in 1 m³ of lead.
So n' = ρ/M where ρ = density of lead = 11.4 g/cm³ = 11.4 g/cm³ × 10⁶ cm³/m³ = 11.4 × 10⁶ g/m³ and M = atomic weight of lead = 207 g/mol
So, n' = ρ/M
N = 11.4 × 10⁶ g/m³/207 g/mol
n' = 0.0551 × 10⁶ mol/m³
n' = 5.51 × 10⁴ mol/m³
Since n' = N/N' where N = number of atoms of lead in 1 m³ of lead and N = Avogadro's constant = 6.022 × 10²³ mol⁻¹
N = n'N' = 5.51 × 10⁴ mol/m³ × 6.022 × 10²³ mol⁻¹
N = 33.18 × 10²⁷ atoms/m³
N = 3.318 × 10²⁸ atoms/m³
So, the number of electron per atom is N" = n/N
= 1.33 × 10²⁹ electrons/m³ ÷ 3.318 × 10²⁸ atoms/m³
= 0.4 × 10¹ electrons/atom
= 4 electrons/atom
PLEASE HELP!! NO LINKS PLEASE REAL ANSWER!!!!!
What will be volume of 20.0 g of CH4 gas at a pressure of 0.950 atm and temperature of 21.0 oc?Question 1 options:
A. 21.8 L
B. 31.8 L
C. 2.27 L
D. 4.27 L
A certain reaction has an activation energy of 51.02 kJ/mol. At what Kelvin temperature will the reaction proceed 4.50 times faster than it did at 365 K
Answer:
[tex]T_2=400.73K[/tex]
Explanation:
From the question we are told that:
Activation energy [tex]E_a= 51.02 kJ/mol.=>51.02*10^3J/mol[/tex]
Reaction Ratio [tex]\triangle K=4.50[/tex]
Initial Temperature [tex]T_1=365K[/tex]
Generally the equation for Final Temperature [tex]T_2[/tex] is mathematically given by
[tex]log \triangle K=\frac{E_a}{2.303R}*(\frac{T_2-T_1}{T_1T_2})[/tex]
Where
[tex]R=Gas constant[/tex]
[tex]R =8.3143[/tex]
Therefore
[tex]log 4.50=\frac{51.2*10^3}{2.303*8.31432}*(\frac{T_2-365}{365*T_2})[/tex]
[tex]log 4.50=7.328*\frac{T_2-365}{T_2}[/tex]
[tex]0.0892=\frac{T_2-365}{T_2}[/tex]
[tex]0.0892T_2=T_2-365[/tex]
[tex]365=T_2-0.0892T_2[/tex]
[tex]365=0.91T_2[/tex]
[tex]T_2=\frac{365}{0.91}[/tex]
[tex]T_2=400.73K[/tex]
sodium bicarbonate =sodium carbonate + water + carbon dioxide gas
Answer: NaHCO3 = Na2CO3 + H2O + CO2
Jim makes a mixture which contains 10 mg of salt, 30 mg of sand, and some iron filings. The total mass of the mixture is 100 mg
Which amount of iron filings does Jim use in the mixture?
A10
B30
C40
D60
Answer:
Amount of iron fillings in mixture = 60 mg
Explanation:
Given:
Total mass of mixture = 100 mg
Amount of salt in mixture = 10 mg
Amount of sand in mixture = 30 mg
Find:
Amount of iron fillings in mixture
Computation:
Using Law of Conservation of mass;
Total mass of mixture = Amount of salt in mixture + Amount of sand in mixture + Amount of iron fillings in mixture
100 = 10 + 30 + Amount of iron fillings in mixture
100 = 40 + Amount of iron fillings in mixture
Amount of iron fillings in mixture = 100 - 40
Amount of iron fillings in mixture = 60 mg
What locations are likely to be affected by an earthquake or tsunami?
San Francisco, California, USA
San Francisco, Tokyo, and Asunción
Tokyo, Japan
None of the locations
Asunción, Paraguay, South America
Answer:
All the locations can suffer earthquakes and a handful like tokyo tsunami so the question is either or so the anwer would be all
Explanation:
why do we have to write the background of the study
Answer:
Writing down background information can help you to remember what you learned and can be used for notes in the future when taking an assessment.
Explanation:
Can I get brainliest? It's for a challenge
What is the correct molecular geometry for NBr2F?
Answer:
Molecular geometry of o3
Ozone has three electron groups around the central oxygen, so has the trigonal planar electron geometry. The molecular geometry is bent: The Effect of Lone Pairs (contd.) With four electron groups (tetrahedral electron geometry), there can be one or two lone pairs around the central atom.
help me with questions 6,11,15,16 and 17 please
ayúdame con las preguntas 6,11,15,16 y 17 por favor
What is the mass of 4 × 1015 atoms of nickel
(Ni)?
Answer in units of g.
A helium-filled balloon contains 0.16 mol He at 101 kPa and a temperature of 23°C. What is
the volume of the gas in the balloon?
V = 3.9 L
Explanation:
Given:
T = 23°C + 273 = 296K
n = 0.16 mol He
P = 101 kPa = 0.997 atm
R = universal gas constant = 0.08205 L-atm/mol-K
V = ?
Using the ideal gas law,
PV = nRT
V = nRT/P
= (0.16 mil He)(0.08205 L-atm/mol-K)(296K)/(0.997 atm)
= 3.9 L
PLEASE HURRY IM TIMED I WILL GIVE BRAINYST (if correct)
What is typical of a grassland? (Select all that apply.)
many trees
grass
wide, open areas
lakes
Answer:grass and wide open areas
Explanation: grassland- large open area of country covered with grass, especially one used for grazing.
Answer:
i needed the answer to this one too
Explanation:
Be sure to answer all parts. Determine the electron-group arrangement, molecular shape, and ideal bond angle for the following molecule: SO3 Electron-group arrangement: V-shaped (bent) trigonal planar trigonal pyramidal seesaw Molecular shape: bent square pyramidal trigonal planar trigonal pyramidal Ideal bond angle: degrees
Answer:
trigonal planar
Explanation:
The molecule SO3 is of the type AX3. The molecule is symmetrical and non polar.
There are three regions of electron density in the molecule. This corresponds to a trigonal planar geometry. This means that the three oxygen atoms are arranged at the corners of a triangle. The bond angle is 120 degrees.
Which of the compounds shown are structural
isomers of this compound? Check all that apply.
A
B
С
D
Answer:
A & C
Explanation:
The next one is A Edge 2022
The compound which are the structural isomers of the given compound is compound A & C.
What are structural isomers?Structural isomers are those isomers in which which are having the same molecular formula but different structural structures.
Compound A: A is the structural isomer of the given compound as they both have same number of carbon and hydrogen atoms present in that.Compound B: B is not the structural isomer of the given ompound as they have not equal number of carbon and hydrogen atoms in it.Compound C: C is the structural isomer of the given compound as they both have same number of carbon and hydrogen atoms present in that.Compound D: D is not the structural isomer of the given ompound as they have not equal number of carbon and hydrogen atoms in it.Hence A & C are the structural isomers of given compound.
To know more about structural isomers, visit the below link:
https://brainly.com/question/26298707
What are the substances that interact to form new substances in a chemical reaction called?
A. Reactants
B. Products
C. Chemicals
D. Substances
Answer:
A. Reactants
Explanation:
A chemical reaction is the process in which atoms present in the starting substances rearrange to give new chemical combinations present in the substances formed by the reaction. These starting substances of a chemical reaction are called the reactants, and the new substances that result are called the products.
Suppose you needed to explain the concept of the mole to a junior high school student. What would you tell them?
Answer:
Explanation:
duehgjvcujhyeq bvckjfdsaeb gjdksghUIBGREQWMNHGTRE BAGTFEQA
hydrogen chloride, hydrogen nitrate (v), sodium chloride, sodium hydroxide. Name a substance known as common salt
Answer:
C: Sodium chloride
Explanation:
Common salt is gotten when sodium atoms reacts with chlorine atoms in an exothermic reaction to form an ionic substance known as sodium chloride with the chemical formula NaCl.
Equation is;
2Na + Cl2 = 2NaCl
Looking at the options, the correct one is Sodium chloride.
Disadvantages of using cisplatin as an anti-cancer drug
Answer: The following side effects are common (occurring in greater than 30%) for patients taking Cisplatin:
Nausea and vomiting. Nausea may last up to 1 week after therapy.
Low blood counts.
Kidney toxicity.
Ototoxicity hearing loss, ringing in the ears.
Blood test abnormalities (low magnesium, low calcium, low potassium)
Explanation:
My mind is ok :')
What is the initial and final mass of the zinc and copper?
Answer:the final mass of copper is 3.84 g. There was an increase in mass of 1.84 g from the initial mass of 2.0 g.
Explanation:
Only electrons in the __________ orbital can form chemical bonds.
Answer:
Electrons in sigma bonds remain localized between two atoms. Sigma bond results from the formation of a molecular orbital by the end to end overlap of atomic orbitals. Electrons in pi bonds can become delocalized between more than two atoms. Pi bonds result from the formation of molecular orbital by side to side overlap of atomic orbitals.
Help solve the types of chemical reactions
[tex]1) \: decomposition[/tex]
[tex]2) \:hydrocarbon \: combustion[/tex]
[tex]3) \: formation[/tex]
[tex]4) \: double - replacement[/tex]
[tex]5 \: double - replacement[/tex]
[tex]6) \: formation[/tex]
[tex]7)double \: - replacement[/tex]
[tex]8) \: double - replacement[/tex]
2+4 help please i will fail 6th grade
Answer:
6
Explanation:
lol
Alkenes provide many ways for incorporating oxygen atoms at specific locations in our molecule.
a. True
b. False
Answer:
True
Explanation:
Answer:
True
hope it is helpful to you