Answer:
A. Circulatory System
i really need help please will give brainliest
Answer:
Astatine is a halogen, Nitrogen is a nonmetal, Krypton is a Nobel gas, Chlorine is a halogen and Sulfur is non metal
Explanation:
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Identify the following structure as an atom, molecule, or compound molecule.
Hydrogen
A.atoms
B. molecules
C.compound molecules
Answer:
A
Explanation:
The answer is A because Hydrogen is an Atom consists of 1 electron only.
Good luck
Criminalist Julie Sandel is investigating a series of threatening notes written in pencil and sent to a local politician. A suspect is arrested and Julie directs the suspect to prepare writing samples to compare to the writing on the notes. She has the suspect sit at a desk in an empty office and gives him a pen and a piece of paper. She begins to read one of the notes and asks the suspect to write the words she dictates. After reading about half a page, she stops, then dictates the same part of the note a second time for the suspect. At one point, the suspect indicates that he does not know how to spell one of the words, so Julie spells it for him. After completing the task, Julie takes the origi- nal notes and the dictated writing from the suspect to a document examiner. What mistakes, if any, did Julie make?
Answer:
See explanation
Explanation:
Julie Sandel, the Criminalist made several mistakes in handling this investigation. They include;
It is true that handwriting can be deduced by comparing a suspects's handwriting to the questioned document, however Julie made a mistake by not making the suspect to write many pages. The suspect may intentionally decide to change his/her hand writing. This trick can be neutralized by asking the suspect to write several pages.
Secondly, the suspect ought to have been given a pencil and paper similar to the one used to write the threatening document. Rather, Julie gave the suspect a pen.
Thirdly, the suspect only wrote half a page instead of a full page. Secondly, Julie took only two exemplars when she should have taken more.
She should not have dictated the spelling of any word to the suspect. The examiner is not supposed to do that.
The threatening documents should have first been shown to the document examiner before taking the exemplars.
picture *** pls help
The volume of Oxygen at STP required : 251.25 L
Further explanationConditions at T 0 ° C and P 1 atm are stated by STP (Standard Temperature and Pressure). At STP, Vm is 22.4 liters/mol.
Reaction(combustion) :
2C₂H₂(g)+5O₂(g)⇒4CO₂(g)+2H₂O(g)
mol C₂H₂ :
[tex]\tt \dfrac{100.5}{22.4}=4.49[/tex]
mol ratio C₂H₂ : O₂ = 2 : 5, so mol O₂ :
[tex]\tt \dfrac{5}{2}\times 4.49=11.23[/tex]
volume O₂ at STP :
[tex]\tt 11.23\times 22.4=251.55~L[/tex]
Or you can use Avogadro's hypothesis :
In the same temperature and pressure, in the same volume conditions, the gas contains the same number of molecules
So the ratio of gas volume will be equal to the ratio of gas moles :
[tex]\tt \dfrac{V_1}{V_2}=\dfrac{n_1}{n_2}\\\\\dfrac{100.5}{V_2}=\dfrac{2}{5}\\\\V_2=\dfrac{100.5\times 5}{2}=251.25~L[/tex]
What is a buffer made from?
A buffer is made from an acid - base conjugate pair as shown by option A
What is a buffer?Buffers are often composed of weak acids and their conjugate bases (or weak bases and their conjugate acids). The weak acid can contribute a proton to balance any new base, whereas the conjugate base can absorb a proton to do so.
This balance between the acid and its conjugate base allows the buffer to survive pH changes. Buffers are essential in biological systems because many biochemical processes are particularly sensitive to pH changes.
Learn more about buffer:https://brainly.com/question/31847096
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Which of the following sets of descriptors matches the molecule below?
Image of two oxygen atoms bonded together to form O2.
A. Compound, allotrope, double bond, one element
B. Molecule, compound, single bond, allotrope
C. Simple structure, diatomic, double bond, molecule
D. Giant structure, single bond, compound, one element
Simple structure, diatomic, double bond, molecule. Hence, option C is correct.
What is a compound?A pure substance made up of two or more different elements combined chemically in a fixed ratio is called a compound.
[tex]O_2[/tex] is a covalent molecule because each oxygen atom needs two valence electrons to complete its octet. To meet this need each oxygen atom shares two of its electrons with the other oxygen forming a strong oxygen-oxygen double-shared covalent bond.
Hence, option C is correct.
Learn more about compounds here:
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Help please and thank you so much
Answer:
A
Explanation:
there cnt be an increase photosynthesis.
surely when its cold,leaves dropped.
Which of the following are soluble in water? Select all that apply.
K2SO4
CaCl2
LiOH
I think it is
K2SO4?
Answer:
1 And 2 are soluble in water
Solid carbon dioxide (CO2), also known as dry
ice, changes into a gas at room temperature. An
image of this change can be seen below.
Is this an example of a physical change? Why
or why not?
Answer:
yes
Explanation:
yes because the ice changes forms physically and can be changed back. not 100% sure tho
Answer:
shiii ion even know like i cant even tell u tha
Explanation:
bro 2 of my bruddas got locked up 2 days ago one of em got shot before the cops took him
are Li, Na and K in the same group
Answer: Yes, they are.
Explanation:
Yes, they are. Li, Na, and K are referring to Lithium, sodium, and potassium.
They are all belonging to the same group which is called the alkali metals group.
They are having the same number of valence electrons i.e. 1.
This group of the alkali metals are considering tree more metals in it which are Rb, Cs, and Fr.
Show your work with good use of units, rounding, and significant figures. [Hint: it is good practice to show the value of your answer before you round off to the final answer with the correct significant figures!]
(8 points) How much heat is required to convert 10.00 g of ice at –20.00°C to water at 25°C. The specific heat of ice is 2.09J/g°C; the specific heat of water is 4.182 J/g°C; the heat of fusion is 333.0 J/g.
Group of answer choices
Heat required : 4.8 kJ
Further explanationThe heat to change the phase can be formulated :
Q = mLf (melting/freezing)
Q = mLv (vaporization/condensation)
Lf=latent heat of fusion
Lv=latent heat of vaporization
The heat needed to raise the temperature
Q = m . c . Δt
1. heat to raise temperature from -20 °C to 0 °C
[tex]\tt Q=10\times 2.09\times (0-(-20)=418~J[/tex]
2. phase change(ice to water)
[tex]\tt Q=10\times 333=3330~J[/tex]
3. heat to raise temperature from 0 °C to 25 °C
[tex]\tt Q=10\times 4.18\times (25-0)=1045~J[/tex]
[tex]\tt Q~tot=418+3330+1045=4793~J\rightarrow rounding~and~2~sig~figs=4.8~kJ[/tex]
another science question plz answer ASAP b/c its timed
Answer:
D
Explanation:
What is the concentration of a stock solution if 20 mL was used to make 400 mL of a 1.44
M solution?
30 M
40 M
50 M
5M
Given :
Volume of stock solution, [tex]V_s = 20\ mL[/tex].
Volume of diluted solution, [tex]V_d = 400 \ mL[/tex].
Molarity of diluted solution, [tex]M_d = 1.44\ M[/tex].
To Find :
The concentration of the stock solution.
Solution :
We know, dilution factor is given by :
[tex]D.F=\dfrac{V_ {diluted}}{V_{stock}}[/tex] ....1)
and [tex]D.F= \dfrac{M_{stock}}{M_{diluted}}[/tex] ....2)
Putting volume in above equation, we get :
D.F = 400/20
D.F = 20
Putting value of D.F in equation 2) we get :
[tex]\dfrac{M_{stock}}{M_{diluted}} = 20\\\\M_{stock} = 20\times 1.44\\\\M_{stock} =28.8\ M[/tex]
The concentration of stock solution is nearest to 30 M.
Therefore, the correct option is 1) 30 M.
How are Earth's continents related?
Please help due at 11:45!
Someone please help will mark as brainliest
Answer:
PET works by using a scanning device (a machine with a large hole at its center) to detect photons (subatomic particles) emitted by a radionuclide in the organ or tissue being examined.
Newer technology combines PET and CT into one scanner, known as PET/CT. PET/CT shows particular promise in the diagnosis and treatment of lung cancer, evaluating epilepsy, Alzheimer's disease and coronary artery disease.
Explanation: Most Brainliest Please
Different isotopes are matched with their uses as (i) Co- 60- To treat cancer (ii) U- 238- To produce electricity (iii) I-131- To treat goitre (iv) Na- 24- In agricultural research Which of the below matches are correct? (i) and (ii) (ii) and (iii) (iii) and (iv) (i) and (iii)
Answer:
I-131- To treat goitre
U- 238- To produce electricity
(ii) (ii) and (iii)
Explanation:
Radioisotopes have various applications in science. These applications may be positive or negative.
I-131- is used to treat goitre. This is a very important medical application of this isotope of iodine.
U-238 is ordinarily non-fissile but can be transformed to Pu-239 and used as a nuclear fuel for electricity generation.
Which element cannot participate in hydrogen bonding?
Carbon dioxide
Explanation:
because when hydrogen mixes with oxygen carbon dioxide is canceled out
Which of the following colors is/are produced when white light from sun is passed through a prism?
Answer:
Options d.
Explanation:
As white light from the sun is passed through a prism, it is separated into colors - red, violet, yellow, blue, green, orange, and indigo.
Dispersion is the process of the separation of visible light into its different component colors. The light waves are refracted as they enter the prism.
So, option d. is correct.
Rubidium is a soft, silvery-white metal that has two common isotopes, 85Rb and 87Rb. If the abundance of 85Rb is 80% and the abundance of 87Rb is 19.8%, what is the average atomic mass of Rubidium?
The average atomic mass of Rubidium : 85.226 u
Further explanationIsotopes are atoms whose no-atom has the same number of protons while still having a different number of neutrons.
So Isotopes are elements that have the same Atomic Number (Proton)
Atomic mass is the average atomic mass of all its isotopes
In determining the mass of an atom, as a standard is the mass of 1 carbon-12 atom whose mass is 12 amu
Mass atom X = mass isotope 1 . % + mass isotope 2.%
The abundance of 85Rb is 80% and the abundance of 87Rb is 19.8%, so the average atomic mass of Rubidium :
[tex]\tt the~average~atomic~mass=0.8\times 85+0.198\times 87\\\\the~average~atomic~mass=\boxed{\bold{85.226~u}}[/tex]
Calculate the atoms of hydrogen in 52.0 g of H2O.
Answer:
34.81 ×10²³ atoms
Explanation:
Given data:
Mass of water = 52.0 g
Number of atoms of hydrogen = ?
Solution:
Number of moles of water:
Number of moles = mass/molar mass
Number of moles = 52.0 g/ 18 g/mol
Number of moles = 2.89 mol
1 mole of water contain 2 mole of hydrogen.
2.89 mole of water contain 2.89× 2= 5.78 moles of hydrogen.
Number of atoms of hydrogen:
1 mole = 6.022×10²³ atoms
5.78 mol × 6.022×10²³ atoms / 1mol
34.81 ×10²³ atoms
Using the model of the periodic table, which element pictured represents an unreactive gas?
Answer:
2
Explanation:
Nobel gasses are not reactive and are the far right group on the periodic table. This is because they have a full valence electron shell which is the most stable electron configuration. Most reactions occur in order for an atom to fill its valence shell and since they already have a full valence shell there is no reason for them to react.
what happens if the temperature of a system at equilibrium is increased?
What is the mass and volume of the nucleus relative to the size of the atom?
Answer:
The atom with the smallest mass is the hydrogen atom; its mass is about 10-27 kg. The masses of other atoms go up to about 200 times this. The nucleus of an atom is about 10-15 m in size; this means it is about 10-5 (or 1/100,000) of the size of the whole atom.
what are the energy transformations taking place in your alarm clock
Answer:
Explanation:
The clock now has potential energy. When the alarm rings, the potential energy is converted into kinetic energy and sound energy.
Alarm clock runs due to the electrical energy. Due to the electric current, the electric motor rotates the blade. It means that the electrical energy is converted into mechanical energy.
The mechanical energy finally generates vibrations which cause sound.
Thus, energy transformation which takes place in alarm clock will follow the order-
Electrical to mechanical to sound.
The elements on the Periodic Table of the Elements are arranged in order of increasing
Answer: The Atomic Number increases. Hope this helps!!!
Explanation:
Elements are arranged from left to right and top to bottom in order of increasing atomic number. Order generally coincides with increasing atomic mass.
Answer:
The Atomic number increases....
Explanation:
Duh
What do you think caused this land formation ?
Observe: Look at the red lithium atom and the blue oxygen atom. Recall that most atoms are stable when their outermost ring has eight electrons. (Some atoms, such as lithium and beryllium, are stable when their outermost ring has two electrons.)
How many electrons will the lithium atom give up to become stable?
1. eight
2. seven
3. two
4. one
Answer:
4. one
Explanation:
which of these is a characteristic
of index fossils
Answer: A index fossil is any animal or plant preserved in the rock record of the earth that is characteristic of a particular span of geologic time or environment. A useful index fossil must be distinctive or easily recognizable, abundant, and have a wide geographic distribution and a short range through time.
Explanation:
What is the redox reaction? And how does the redox reaction happen inside batteries?
Answer:
It is called a reduction-oxidation, oxide-reduction reaction, or simply as a redox reaction, any chemical reaction in which one or more electrons are transferred between the reactants
Redox battery is an example of both a Flow Battery and a two electrolyte system.In this case, it depends on two different active aqueous electrolytes of vanadium dissolved in sulfuric acid separated by a membrane at which ionic interchange takes place.
Thats my opinión though.
5. True or False: A growth rate can be only positive and negative, it can never be zero.....
A. True
B. False
Answer:
True
Explanation: