Answer:
Paratroopers not hurt while landing because when they get to the ground, they keep their knees and feet together helping them to land properly.
hope it helps!
Answer:
they usually land on their knees and roll
Explanation:
A scientist provides 454 kJ of energy to a covalent compound in order to start a reaction. As a result, heat is released. Which statement is true about this experiment?
The amount of energy produced is more than 454 kJ.
The amount of energy produced is equal to 454 kJ.
The amount of energy produced is less than 454 kJ.
The amount of energy produced is at least double that of 454 kJ.
Answer:
The amount of energy produced is less than 454 kJ.
Explanation:
I do not know but if am wrong you can correct me. I need your help for business, english and chemistry questions on my profile. So can you and the other person who commented and go on my profile please...? the due date already gone 12 days ago.
How many atoms are in a casein molecule?
You have just started working at a swimming pool supply store and they have nitric acid on their shelves. In order to help customers adjust the pH of their swimming pool you must know many details about this chemical. Due to air conditioning the store is always at 25 degrees Celsius. The label on the nitric acid bottle is marked as 0.0155 mol/L. What is the hydronium ion concentration?
Answer:
The concentration of hydronium ions is 0.0155 mol/L
Explanation:
The aqueous solution ionization reaction for nitric acid is as follows;
HNO₃ + H₂O → NO₃⁻ + H₃O⁺
Whereby HNO₃ is a strong acid and it undergoes complete ionization in an aqueous solution
Hence one mole of HNO₃ produces one mole of H₃O⁺ ions
0.0155 mol/L HNO₃ will have 0.0155 moles of H₃O⁺ in one liter of the solution
The concentration of hydronium ions = 0.0155 mol/L.
What are electromagnetic waves, and how can they be seen?
radio waves, microwaves, infrared, light, ultraviolet, X-rays, and gamma rays. Your mind interprets the energies of light as different colors, from red to violet.
In calculating the mass of an atom the mass of the electrons is essentially
Answer:
Sex
Explanation:
How many moles of MgCl2, are in 400. L of a 0.021 M solution?
A 0.75 mol
B 8.4 mol
C 7.5 mol
D 0.84 mol
Answer:
The correct answer to the following question will be Option B "8.4 mol".
Explanation:
The given values are:
Molarity of a solution = 0.021 M
Litres of solution = 400 L
Let the moles be "x".
As we know,
⇒ [tex]Molarity = \frac{Moles \ of \ solute}{Litres \ of \ solution}[/tex]
On putting the estimated values, we get
⇒ [tex]0.021=\frac{x}{400}[/tex]
On applying cross-multiplication, we get
⇒ [tex]x =0.021\times 400[/tex]
⇒ [tex]x=8.4 \ mol[/tex]
The flesh of a cut apple turns brown when left out in the air. Is this a chemical change or a physical change? Why?
Answer:
Chemical Change
Explanation:
apples turn brown because of a chemical reaction named oxidation which is cause by oxygen of the air
Oxygen is one of the most reactive chemicals known to exist.. There are a variety of oxidation reactions .. The fridge does not stop chemical reactions so bacteria will still rot the food eventually and out side of the fridge it would rot quicker than the fridge .
Answer:
Chemical change
i got it right
Explanation:
H2SO4 + 2NaOH - Na2SO4+ 2H20
In a titration, 5.0 ml of 1.0 M H2SO4 solution is neutralized by 8.0 ml of an NaOH solution of unknown
concentration. The concentration of the NaOH is -
OA 2.0 M
OB 1.0 M
OC 0.63 M
OD 1.3 M
Answer:
It takes 83 mL of a 0.45 M NaOH solution to neutralize 235 mL of an HCl ... 2). You are titrating an acid into a base to determine the concentration of the base. The endpoint of the neutralization is reached but the stopcock on the buret sticks slightly ... 5). It takes 12.5 mL of a 0.30 M HCl solution to neutralize 285 mL of NaOH ...
Explanation:
A weather balloon has a maximum volume of 6.25 x 10^3 L. The balloon contains 510. L of helium gas at a pressure of 0.882 atm. What will be the pressure when the balloon is at maximum volume?
A 72.0 atm
B .0720 atm
C 2,811,375 atm
D 22.4 atm
Answer:
0.0720 atm
Explanation:
Boyle's Law
Describe, in detail, the arrangement of the periodic table, and why it is sometimes referred to as the "chemists' calendar". Describe the rows and columns. What do they tell us about the elements in each row or column? What other trends are on the periodic table?
Answer:
The periodic table is an arrangement of chemical elements based on increasing atomic numbers.
Explanation:
The periodic table is an arrangement of chemical elements in order of increasing atomic numbers. According to the modern periodic law, the properties of elements is a periodic function of their atomic numbers.
The periodic table is arranged in columns and rows. The columns are called groups of elements. All elements in the same group have the same number of electrons on their outermost shell hence they possess the same chemical behavior. Elements across a period have the same number of shells thus they have the same maximum excitation level.
There are important trends across the periodic table such as atomic radius, ionic radius, electro negativity, electron affinity, melting and boiling points, metallic properties etc. All these depend on an elements position in the periodic table. periodic properties of elements increase or decrease across the period or increase or decrease down the group as the case maybe.
Hence, just as one can easily read off the date and make predictions based on dates shown in a calendar, a chemist can read off the properties of elements and make predictions about the reactivity and physical properties of elements based on their relative position in the periodic table.
Gradual changes that occur down the group in the periodic table are called group trends and they usually very significant in discussing the properties of members of a group.
Answer:
The periodic table is an arrangement of chemical elements based on increasing atomic numbers.
Explanation:
The periodic table is an arrangement of chemical elements in order of increasing atomic numbers. According to the modern periodic law, the properties of elements is a periodic function of their atomic numbers.
The periodic table is arranged in columns and rows. The columns are called groups of elements. All elements in the same group have the same number of electrons on their outermost shell hence they possess the same chemical behavior. Elements across a period have the same number of shells thus they have the same maximum excitation level.
There are important trends across the periodic table such as atomic radius, ionic radius, electro negativity, electron affinity, melting and boiling points, metallic properties etc. All these depend on an elements position in the periodic table. periodic properties of elements increase or decrease across the period or increase or decrease down the group as the case maybe.
Hence, just as one can easily read off the date and make predictions based on dates shown in a calendar, a chemist can read off the properties of elements and make predictions about the reactivity and physical properties of elements based on their relative position in the periodic table.
Gradual changes that occur down the group in the periodic table are called group trends and they usually very significant in discussing the properties of members of a group.
Explanation:
How does the difference in electronegativity values determine the type of bond that occurred? Ionic or covalent
How much energy is released when 22.4g of CH4 is burned?
The combustion of methane, CH4, releases 890.4 kJ/mol. That is, when one mole of methane is burned, 890.4 kJ are given off to the surroundings. This means that the products have 890.4 kJ less than the reactants.
Combustion of one mole or 16 g of methane gas releases 810 kJ of heat energy. Thus, heat released by the combustion of 22.4 g of methane is 1134 kJ.
What is combustion?Combustion of a substance is its reaction with atmospheric oxygen producing carbon dioxide and water. Combustion of hydrocarbons gases takes places easily and can be burned easily for fuels.
The chemical equation of combustion of methane is written below:
[tex]\rm CH_{4} + 2O_{2} \rightarrow CO_{2} + 2H_{2}O[/tex]
This is an exothermic process and heat is released from the reaction system.
The heat released by the combustion of one mole of methane is 810 kJ.
molar mass of methane = 16 g/mol
no.of moles in 22.4 g = 22.4/16 = 1.4 g
Thus, heat released by 1.4 moles = 1.4 ×810 kJ =1134 kJ.
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How do you think climate change affected the strength of the hurricane?
any object that travels around another object in space is a (n) -
Answer:
The answer is Satellite
Explanation:
Identify whether each of these hydrocarbons is saturated or unsaturated. Place an "S" for "saturated" next to each hydrocarbon letter that is saturated. Place a "U" for "unsaturated" next to each hydrocarbon letter that is unsaturated.
A. 2 central carbons, with C H 3 at each end, and also single bonded to the first carbon.B. 3 central carbons, with the first 2 double bonded to each other. The left end is bonded to C H 3, and the right end is bonded to 3 C H 3.C. 2 central carbons, with H above, below, and to both sides.D. 5 central carbons, with H above and below each, and H and to both ends of the chain.
ANWSERS:
A. ⇒ S
B. ⇒ U
C. ⇒ S
D. ⇒ S
You're welcome >:D
Answer:
A = S
B = U
C = S
D = S
Explanation:
Among the given compounds, compounds (A), (C) & (D) are saturated hydrocarbons and compound (B) is an unsaturated hydrocarbon.
What is hydrocarbons?Hydrocarbons are those compounds in which carbon atom is present in addition to the hydrogen atoms.
Saturated compounds are those compounds in which only single bonds are present between two carbon atoms.Unsaturated compounds are those compounds in which double or triple bonds are present between two carbon atoms.So, according to the data given in the question it is clear that compound (A), (C) and (D) are saturated compounds as in these only single bonds are present and compound (B) is an unsaturated compound because of the presence of the double bonds.
Hence only compound (B) is an unsaturated compound.
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A 1,000-mL sample of ethanol is tested. Its boiling point is determined to be 78.4°C. What is the most reasonable prediction of the boiling point for a 100-mL sample of ethanol?
Answer:
78.4°C
Explanation:
Boiling point does not depend on the mass of the substance present, only the heat content is a function of the mass or volume of the substance in consideration. If there is 1000 ml of ethanol and it boils at 78.4°C, a 100 ml sample too should boil at the same temperature of 78.4°C.
How did greenhouse gasses get their name?
Answer:
Greenhouse gasses got their name from a greenhouse
Explanation:
Since greenhouses have plants inside in which the building lets sunlight in to the plants and greenhouse gasses trap heat. (sorry if my answer is confusing)
The thermochemical equation shows the combustion of carbon in oxygen. How many moles of carbon, C must be burnt to produce 196.5 kJ of heat?
Given thermochemical equation; C(s) + O2(g) -> CO2(g) = -393 kJ mol ‐¹
Answer:
0.5 moles OF CARBON WILL BE BURNT SHOULD 196.5 kJ OF HEAT IS LIBERATED IN THE REACTION.
Explanation:
The standard heat of combustion of a substance is the heat evolved when one mole of the substance is burned completely in oxygen under standard conditions.
From the reaction, -393kJ of heat is required to burn 1 mole of Carbon completely in oxygen.
C(s) + O2 (g) -----> CO2(g) -393 kJ mol^-1
Should 196.5 kJ of heat was evolved by the reaction, the number of moles of carbon to be produced will be x moles;
-393 kJmol^-1 of heat was required to burn 1 mole of Carbon
196.5 kJ/mol of heat will burn x moles of carbon.
x = ( 196.5 * 1 / -393)
x = -0.5 moles
0.5 moles of carbon will be burnt when 196.5 kJ of heat is liberated
A reaction is monitored and the products are found to be a salt and water. The reactant(s) must have been___
A sample of grape juice has a hydroxide ion concentration of 1.4 × 10-10 M. Which of these equations will you use to find the hydronium ion concentration?
Explanation:
Since [H+] [OH-] =10^(-14)
[H+] = (10^-14) / (1.4×10^-10)
How much solute will remain undissolved when 180 g of potassium iodide is added in 100 cm3 of water at 30°C?
Answer:
[tex]m_{undissolved}=27g[/tex]
Explanation:
Hello,
In this case, we first define the solubility as the maximum amount of a solute that is completely dissolved in an specific amount of solvent and it is temperature-dependent. Thus for potassium iodide, its solubility at 30°C is 153 g per 100 cm3 of water, therefore, with the given amount, the undissolved amount results:
[tex]m_{undissolved}=180g-153g=27g[/tex]
Best regards.
Water is treated at a water works to make it fit to drink. What is present in the water when it leaves the waterworks?
Answer:
Supplements and disinfecting chemicals
Explanation:
The major stages of water treatment are; coagulation, sedimentation, filtration and disinfection. Coagulation has to do with adding a coagulant such as potash alum which causes the impurities to clump together and form big particles called flocs. These settle down rapidly under gravity and the water is passed through a filter bed to remove fine particles. The water is now disinfected by the addition of chemicals such as chlorine. Supplements such as iodine and flourine may also be added to the water.
Contact process is operated at low pressure high temperature and V2O5 are conditions required for the contact process. The contact process is used to produce sulphuric acid from sulphur.
When the water leaves the waterworks, there has been the presence of chlorine as well as soluble substances. The reaction has been processed by utilizing Vanadium oxide as a catalyst, at low pressure and high temperature. Thus option D is correct.
Water has been made to work with the waterworks to make it fit for the drinking purpose. The process removes the access of contaminants from the water, by removing the toxins water has been made suitable for drinking purposes.
The disinfectants have been added to the water to chemically treat the water at waterworks. Chlorine has been the chemical widely used for disinfection purpose. Thus, when the water leaves the waterworks, there has been the presence of chlorine as well as soluble substances such as minerals that made water suitable for drinking.
The contact process has been the modern process used by the industries for the manufacturing of Sulfuric acid. The process has been a catalyze-mediated reaction in which there has been the formation of sulfur trioxide intermediate by the reaction of sulfur dioxide and oxygen. The reaction has been processed by the dissociation of sulfur trioxide to sulfuric acid on reacting with water.
The reaction has been processed by utilizing Vanadium oxide as a catalyst. The reaction has been processed at low pressure and high temperature. Thus option D is correct.
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Why are alloys useful?
Answer:
Yes, they are useful.
Explanation:
They allow us to make use of strengths and benefits of a particular element while not being hampered by it's faults.
can u answer this?
Mass: 126 g
Volume: 15 cm to the third power
Density:?
Answer:
Calculate density
Weight/mass
126
g
Volume
15
cm³
Density
8,400
kg/m³
Explanation:
What is one common reaction to all hydrocarbons?
Answer:
Common properties of hydrocarbons are the facts that they produce steam, carbon dioxide and heat during combustion and that oxygen is required for combustion to take place. The simplest hydrocarbon, methane, burns as follows: CH4 + 2 O2 → 2 H2O + CO2 + energy.
Explanation:
Practice with Dilution Calculations IV,
12V
1. What is the initial volume of a 15.0 M stock solution which has been diluted to a final volume of
250.-ml at a concentration of 2.35 M?
Answer:
THE INITIAL VOLUME OF THE STOCK SOLUTION IS 0.0392 L OR 39.2 mL
Explanation:
To calculate the volume of a solution before dilution, we make use of the dilution formula;
C1 V1 = C2 V2
C1 = the concentration of the stock solution = 15 M
V 1 = the volume of stock solution = ?
C2 = concentartion of final solution = 2.35 M
V2 = volume of final solution = 250 mL = 250/ 1000 = 0.25 L
Rearranging the formula, we obtain;
V1 = C2V2 / C1
V 1 = 2.35 * 0.25 / 15
V1 = 0.5875 / 15
V1 = 0.0392 L
the initial volume of the stock solution is 0.0392 L or 39.2 mL
PLEASE HELP DUE AT 2PM I'M DESPERATE, WILL GIVE BRAINLEST!!
1. When magnesium is burned in air, its mass increases. Explain why this is.
2. When a match is burned in air, its mass decreases. Explain why this is.
3. This equation is unbalanced Na + F2 → NaF. Explain how you know it is unbalanced.
4. Why does it need to be balanced? Refer to the conservation of mass in your answer
5. A student heats up a metal and finds that its mass increases. The students says “this is because heat has been added.” Explain why this is incorrect.
Answer:
Ans no 1. As magnesium used to react with oxygen and due to the reaction the mass (weight) of magnesium increases , this reaction between oxygen and magnesium which form magnesium oxide in the air by forming white smoke increases the mass of magnesium
explain how iodine can be obtained from iodine-sodium chloride mixture
The pH of a solution is 7.880. What is the concentration of [H30+] in the solution ?
Answer:
the concentration is 10^(-8) M
The concentration of [H30+] in the solution when the pH of the solution is [tex]1.32*10^8\ m.[/tex]
Calculation of the concentration:Since The pH of a solution is 7.880
So here
pH = -log{H+}
{H+} = [tex]10^-PH[/tex]
[H30+] [tex]= 10^{-7.88}[/tex]
[tex]= 1.3182*10^-8\ mol\\\\= 1.32*10^-8\ m[/tex]
hence, The concentration of [H30+] in the solution is [tex]1.32*10^8\ m.[/tex]
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Flexible expenses _________ from month to month.
A.
vary
B.
increase
C.
decrease
D.
remain unchanged
Answer:
A
Hope this helps.
Answer:
A. vary
Explanation: