how does skin protect the body from pathogens?
Answer:
It blocks pathogens from getting inside our body.
Explanation:
The skin is the biggest organ, it cover the whole body and organ system from any toxic things.
PLS PLS PLS HELP ME I WILL MARK YOU BRAINLYEST PLSSSSS :((
A wheelbarrow has wooden handles that are 3.5 feet long. The axle on the wheel is the
fulcrum and is 0.5 feet from the end. What is the MA? You know you can probably lift 70
pounds without too much effort. How heavy of a wheelbarrow load can you lift?
Please answer
You witnessed a student throw away a broken beaker in the regular trash can. Which of the following is the most important reason to alert your instructor?
Answer:
D
Explanation:
Provide background information about different types of chemical reactions.
Synthesis Reactions
Decomposition Reactions
Single Replacement Reaction
Double Replacement Reaction
Combustion
Then explain, in a general sense, how you will determine which of the above types of reactions are occurring in your experiments.
Answer:
.
Explanation:
-Synthesis reactions are reactions that appear when two distinct atoms or molecules engage to structure a specific molecule or compound. Most of the time, when a synthesis response occurs, electricity is launched and the response is exothermic. However, an endothermic consequence is additionally possible.
-A decomposition response starts offevolved from a single substance and produces extra than one substance; that is, it decomposes. One substance as a reactant and greater than one substance as the merchandise is the key attribute of a decomposition reaction. For example, in the decomposition of sodium hydrogen carbonate (also recognized as sodium bicarbonate)
-A single-replacement response (sometimes referred to as a single-displacement reaction) is a chemical response in which one aspect is substituted for every other factor in a compound, producing a new aspect and a new compound as merchandise
-A double-replacement response (sometimes referred to as a double-displacement reaction) takes place when components of two ionic compounds are exchanged, making two new compounds. A attribute of a double-replacement equation is that there are two compounds as reactants and two distinctive compounds as product
-A combustion response happens when a reactant combines with oxygen, many instances from the atmosphere, to produce oxides of all different factors as products; any nitrogen in the reactant is transformed to elemental nitrogen, N2. Many reactants, referred to as fuels, incorporate normally carbon and hydrogen atoms, reacting with oxygen to produce CO2 and H2O
A chemical reaction may involve one or more reactants to yiled one or more products.
Types of reactionsBelow we are going to discuss the types of reaction under the following headings;
Synthesis reaction - This is a reaction in which two or more substances come together to yiled a single product.
Decomposition reaction - This involves the breakdown of a substance into new substances.
Single Replacement Reaction- This is a type of reaction in which an atoms replaces another in a compound.
Double Replacement Reaction - This is a reaction in which cations exchange anion partners in a reaction
Combustion - This is a reaction in which a substance is burnt in oxygen.
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Balance the following equations:
i. H2SO4 + ….NaHCO3 → Na2SO4 + ….H2O + ……CO2
ii. H2 + I2 → ….HI
iii. …..NaOH + H2SO4 → Na2SO4 + …..H2O
iv. ……FeSO4 → Fe2O3 + SO2 + SO3
v. C3H6O2 + …..O2 → ….CO2 + …..H2O
b) Calculate the molecular masses of the following:
i. H2SO4
ii. CH4
iii. NH3
c) 56g of iron reacts with 71g of chlorine. How many grams of iron react with 35.5g of chlorine?
(I) [tex]H_2SO_4+ 2NaHCO_3--> Na_2SO_4 + 2 H_2O + 2CO_2[/tex]
(II) [tex]H_2+I_2 --> 2HI[/tex]
(III) [tex]2NaOH+H_2SO_4--> Na_2SO_4+ 2H_2O[/tex]
(IV) [tex]2FeSO_4--> Fe_2O_3+SO_2+SO_3[/tex]
(V) [tex]2C_3H_6O_2+7O_2-->6CO_2+6H_2O[/tex]
_____________________________________Molecular Masses of the following:------------------------------------------------------------------------------------------------------------
(I) [tex]H_2SO_4[/tex]
(ANS) [tex]98 \frac{grams}{mol}[/tex]
__________________________________________________________
Solution:
Molecular mass of,
H = 1
S = 32
O = 16
Now,
There are 2 atoms of Hydrogen, 1 atoms of Sulfur and 4 atoms of Oxygen present, thus,
[tex]H_2SO_4 = (1x2)+32+(16x4)[/tex]
[tex]H_2SO_4 = 98 \frac{grams}{mol}[/tex]
_____________________________________(II) [tex]CH_4[/tex]
(ANS) [tex]16 \frac{gram}{mol}[/tex]
_________________________________________________________
Solution:
Molecular Mass,
Carbon = 12
Hydrogen = 1
Now
There are 1 atom of Oxygen and 4 atoms of Hydrogen present, thus,
[tex]CH_4 = 12 + (1x4)[/tex]
[tex]CH_4 = 16\frac{grams}{mol}[/tex]
_____________________________________(III) [tex]NH_3[/tex]
(ANS) [tex]17 \frac{grams}{mol}[/tex]
__________________________________________________________
Solution:
Molecular Mass,
Nitrogen = 14 grams
Hydrogen = 1
Now,
There are 1 atoms of Nitrogen and 3 atoms of Hydrogen present, thus,
[tex]NH_3 = 14 + (1x3)[/tex]
[tex]NH_3 = 17 \frac{grams}{mol}[/tex]
_____________________________________How many Grams of Iron(fe):[tex]Fe + Cl_2 --> FeCl_2[/tex]56 71
x 35.5
_____________________________________[tex]X = \frac{56 x 35.5}{71}[/tex]
Simplify the equation
X = 28 grams
__________________________________________________________
Answer:
28 grams of Iron(fe) will react with chlorine.
_____________________________________Best Regards,'Borz'i need help ASAP plz its timed
Answer:
B) iron (Fe) im sure its iron
Answer fast please What system is the heart part of
A. Circulatory
B. Respiratory
C. Digestive
D. Skeletal
Answer:
A. Circulatory System
i need so much help 50 points!!!!!! complete the graph
*WILL GIVE A BRAINIEST & 15 POINTS TO THE CORRECT ANSWER*
When an electron falls back to its original shell, the electron will...
A.) absorb energy as it goes to the excited state
B.) absorb energy as it goes to the ground state
C.) release energy as it goes to the excited state
D.) release energy as it goes to the ground state
Answer: D
Explanation:
what is the atomic number of an element based on
Answer:
The atomic number is the number of protons in the nucleus of an atom . The number of protons define the identity of an element
Consider the balanced equation. PCl3 + 3H2O Right arrow. H3PO3 + 3HCl What is the percent yield of HCl if 42.0 g of HCl are produced from the reaction of 62.0 g of PCl3? Use Percent yield equals StartFraction actual yield over theoretical yield EndFraction times 100..
Answer:
Percient yield of reaction: 85 %
Explanation:
The reaction is:
PCl₃ + 3H₂O → H₃PO₃ + 3HCl
We only have data from the chloride, so we assume water is in excess. We convert the mass to moles:
62 g . 1mol / 137.32 g = 0.452 mol
If ratio is 1:3, from 0.452 mol we would produce three times as big, that amount. (0.452 . 3) = 1.36 moles of HCl.
We convert the amount to mass.
1.36 mol . 36.45g / 1mol = 49.4 g
This value of produced HCl is the theoretical yield. To determine the percent yield we make:
(Yield produced / Theoretical yield) . 100
(42 g / 49.4g) . 100 = 85%
Answer:
Yes it is 85.0%
Explanation:
may we met again !
i love you,ella
Answer: When I see you again!
Explanation:
PLEASE HELP, I WILL MAKE YOU THE BRAINLIEST!!!
3. Magnesium sulfate is added to sodium hydroxide to produce sodium sulfate and magnesium hydroxide (10 points)
a. Write the skeletal equation and Balance the chemical equation describing the reaction above.
b. What kind of reaction is this?
c. Rewrite the balanced chemical equation, adding state symbols for all compounds in the reaction.
Answer:
answer in the picture hi shirllleeyyyyy
A cylinder, with a piston pressing down with a constant pressure, is filled with 2.10 moles of a gas (n1), and its volume is 46.0 L (V1). If 0.700 mole of gas leak out, and the pressure and temperature remain the same, what is the final volume of the gas inside the cylinder?
Answer:
The volume is [tex]V_2 =15.33 \ L[/tex]
Explanation:
From the question we are told that
The number of moles of the gas is [tex]n_1 = 2.10 \ moles[/tex]
The volume of the gas is [tex]V = 46.0 \ L[/tex]
The of moles of the gas that leaked is [tex]n_2 = 0.700 \ mol[/tex]
Generally from the ideal gas law
[tex]PV = nRT[/tex]
Generally at constant pressure and temperature
[tex]\frac{V}{n} = constant[/tex]
So [tex]\frac{V_1 }{n_1} = \frac{V_2 }{n_2}[/tex]
=> [tex]V_2 = \frac{ V_1 * n_2 }{ n_1}[/tex]
=> [tex]V_2 = \frac{ 46.0 * 0.700 }{ 2.10 }[/tex]
=> [tex]V_2 =15.33 \ L[/tex]
how many valence electrons does Ne have
Answer:
eight valence electrons
Answer:
it has 8 valence electrons
27. Based on Reference Table S, which of the
following atoms requires the least energy for the
removal of the most loosely bound electron?
A) Br
B) Sr
C) Be
D) Sn
Answer:
This question is incomplete but the correct option is B
Explanation:
This question is incomplete because of the absence of the "Reference Table S", however the question can still be answered in the absence of the table. The energy described in the question is the ionization energy (energy required to remove the most loosely bound electron in an atom). This question seeks to know the atom (from the options provided) with the least ionization energy.
Ionization energy increases from left to right across the period because it's easier to remove a single electron (valence electron) from the outermost shell than to remove two electrons from the same shell; thus the more the valence electrons (in a shell), the higher the ionization energy. Thus, bromine (Br) and tin (Sn) have high ionization energies because they have more number of electrons in there outermost shell.
Berylium (Be) and strontium (Sr) are both in the group 2 of the periodic table because they both have 2 electrons in there outermost shell. Ionization energy decreases down a group. This is because the farther an electron is from the nucleus, the weaker the force of attraction between the nucleus and the electron. Thus, strontium (Sr) would have a lesser ionization energy between the two and would indeed have the least ionization among the options provided. Hence, the correct option is B
You are sitting in the central park bleachers of a Major League baseball park. You see a batter strike a pitched ball. About 0.4 seconds later you hear the contact between the bat and the ball. In terms of the properties of light and sound waves, how do you explain the difference in the communications you receivedbabout the same event?
Answer:
See the answer below
Explanation:
The speed of light in air and space is faster than the speed of sound in the same media. Light travels with a speed of approximately 3 x [tex]10^8[/tex] m/s while sound can only travel at 343 m/s (at 20 [tex]^oC[/tex]).
Consequently, the visuals of a batter striking a pitched ball which travel by light and is perceived through the eyes would be seen before the sound of the strike.
The difference in the speeds of light and that of sound largely explains the difference in the communication received about seeing a batter striking a pitched ball before hearing the sound of the strike
How many molecules are present in 3HNO4?
1) 14
2) 18
3) 3
4) 4
Answer:
2
Explanation:
If you take H and N, that is two molecules right off the bat. If you take O4, that makes 6. Take the total of all 6, and multiply it by 3, with equals 18.
3HNO4 = 18
If there are 400 radioactive atoms in a sample, how many will remain after four half-lives have passed?
Enter the exact number as your answer. Do not spell out the number.
Answer:
25 atoms
Explanation:
Given data:
Total number of atoms = 400 atom
Atoms remain after 4 half lives passed = ?
Solution:
At time zero = 400 atom
At first half life = 400 atom/2 = 200 atom
At 2nd half life = 200 atom/2 = 100 atom
At 3rd half life = 100 atom/2 = 50 atom
At 4th half life = 50 atom/2 = 25 atom
Thus, 25 atoms are remained after 4 half lives.
25 atoms of the radioactive atoms will remain after 4 half lives.
Given in the question,
Initial amount of a radioactive element = 400 atomsNumber of half lives = 4Expression for the amount remaining of a radioactive element after 'n' half lives is given by,
[tex]N=N_0(\frac{1}{2})^n[/tex]
Here, [tex]N_0=[/tex] Initial amount
[tex]n=[/tex] Number of half lives
By substituting the vales of [tex]N_0[/tex] and [tex]n[/tex] in the question,
[tex]N=400(\frac{1}{2})^4[/tex]
[tex]=\frac{400}{16}[/tex]
[tex]=25[/tex]
Therefore, 25 atoms of the radioactive atoms will remain after 4 half lives.
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What is the difference between moles and mass?
How many atoms of S are in the following formula: 3Na(SO4)2
1) 6
2) 8
3) 3
4) 5
Answer:
6
Explanation:
Which could cause renewable resources to change from renewable to non- renewable?
A. Pollution
B. Overuse
C. Disease
D. All of these
what properties of gold and platinum make these metals desirable for jewelry?
Answer: They are non-reactive and don't conform with other elements to form compounds. Because they are non-reactive, they don't corrode easily.
Explanation:
The properties of gold and platinum which make these metals desirable for jewelry is due to their electronic configuration due to which they are non-reactive and do not corrode easily.
What is electronic configuration?Electronic configuration is defined as the distribution of electrons which are present in an atom or molecule in atomic or molecular orbitals.It describes how each electron moves independently in an orbital.
Knowledge of electronic configuration is necessary for understanding the structure of periodic table.It helps in understanding the chemical properties of elements.
Elements undergo chemical reactions in order to achieve stability. Main group elements obey the octet rule in their electronic configuration while the transition elements follow the 18 electron rule. Noble elements have valence shell complete in ground state and hence are said to be stable.
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You mix 15g of water with 10 grams of sodium chloride. After the reaction occurs, how
many grams of your new substance do you have?
A) 15g
B) 25g
C) 20g
D) not enough information
Answer:
B) 25g
Explanation:
Every reaction must follow the law of conservation of mass.
Law of conservation of mass:
According to the law of conservation mass, mass can neither be created nor destroyed in a chemical equation.
Explanation:
This law was given by French chemist Antoine Lavoisier in 1789. According to this law mass of reactant and mass of product must be equal, because masses are not created or destroyed in a chemical reaction.
For example:
In given photosynthesis reaction:
6CO₂ + 6H₂O + energy → C₆H₁₂O₆ + 6O₂
there are six carbon atoms, eighteen oxygen atoms and twelve hydrogen atoms on the both side of equation so this reaction followed the law of conservation of mass.
In given example:
Water + sodium chloride → Product
15 g + 10 gram = 25 g
25 g = 25 g
Calculate the speed of a bicycle
traveling 20 km in 2 hours. Show the
formula, and your work with the correct
units. HELP PLEASE AND HURRY
Answer:
10 km/hr
............
The speed of a bicycle is 10 km/hour or 0.27 m/sec.
What is the Speed?The speed may be defined as the rate of change of position of an object in any direction. It is significantly measured as the ratio of distance to the time in which the distance was covered. Speed is a type of scalar quantity that has only direction but no magnitude.
According to the question, the distance traveled by bicycle = 20 km or 2000 meters.
The total time is taken = 2 hours or 7200 seconds.
Now, the formula for calculating the speed is as follows:
S = Distance/ Time = 20km/2 hours = 10 km/hour.
S = Distance/ Time = 2000 meters/7200 seconds = 0.277 m/sec.
Therefore, the speed of a bicycle is 10 km/hour or 0.27 m/sec.
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Which statement about plant and animal cells is true? A. Plant cells have a nucleus and a cell wall; animal cells do not have either of these structures. B. Plant cells have a cell wall and chloroplasts; animal cells do not have either of these structures. C. Plant cells have a cell wall and a cell membrane; animal cells have a cell wall but not a cell membrane. D. Plant cells have chloroplasts and mitochondria; animal cells have chloroplasts but do not have mitochondria.
Answer:
B. Plant cells have a cell wall and chloroplasts; animal cells do not have either of these structures.
Explanation:
A major difference between a plant cell and an animal cell is presence of chloroplasts in plant cells. Another key difference between plant and animal cells is the presence of a cell wall in plant cells. Both structures are absent in an animal cells.
The cell wall surrounds the plasma membrane of plant cells. This helps to provide the required tensile strength and protection against mechanical and osmotic stress.
Cell walls also help plants to maintain shape and rigidity.
The plant cell has a cell wall and chloroplast, while the animal cell lacks both of them. Thus, option B is correct.
The cell has been the smallest unit of life that has been performing varying functions with the help of different organelles.
The plant cell has been exposed to harsh environmental conditions, thus has been consisting of the cell wall along with the cell membrane. However, animal cell lacks a cell wall.
The food has been processed in the plant cells with the help of photosynthesis that required chlorophyll. The chlorophyll has been consisted in the chloroplast. Thus plants cell have consisted of chloroplast, however, animal cells lack chlorophyll as well as chloroplasts.
Thus, the plant cell has a cell wall and chloroplast, while the animal cell lacks both of them. Thus, option B is correct.
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1. The ability to reflect light; shininess
ductility
O luster
o conductivity
o malleablity
Answer:
Luster
Explanation:
I can not really explain
-the metallic substance
lonic bonds tend to form between
a. nonmetals; nonmetals
b. metals; nonmetals
c. metals; metals
d. all of these
For all of these it’s Explanation with support:
1. The color of a solution identifies if it is an acid, base, or neutral solution
2. Which solution is basic
3. How will adding water effect the pH
Answer:
1. A
Explanation:
1.A True we can identify solutions based on the color of the solutions. If you look at our universal PH color chart. Red, Orange, and yellow are acids.
2. D, If you look at the pH levels. Both B and C have a pH level equal to or greater than 7. Note that any pH level 7 or higher is a basic solution.
3.A
Looking at the pH level we can see that this is an acidic solution. So, by adding more water. The acidity will lessen.