According to specific heat capacity, 3.010 kilojoules of energy is released when 12.8 g of steam at 120.0 °C is condensed to give liquid water at 64.0 °C .
What is specific heat capacity?Specific heat capacity is defined as the amount of energy required to raise the temperature of one gram of substance by one degree Celsius. It has units of calories or joules per gram per degree Celsius.
It varies with temperature and is different for each state of matter. Water in the liquid form has the highest specific heat capacity among all common substances .Specific heat capacity of a substance is infinite as it undergoes phase transition ,it is highest for gases and can rise if the gas is allowed to expand.
It is given by the formula ,
Q=mcΔT, substitution of values in formula gives Q=12.8×4.2×56=3010 J or 3.010 kJ.
Thus, 3.010 kilojoules of energy is released when 12.8 g of steam at 120.0 °C is condensed to give liquid water at 64.0 °C .
Learn more about specific heat capacity,here:
https://brainly.com/question/29766819
#SPJ1
Calculate the velocity of these electrons. The mass of an electron is equal to 9.10938 × 10e–31 kg, the speed of light (c) is equal to 3.00 × 10e8 m/s, and Planck's constant is h = 6.626 × 10e–34 J•s.
The mass of an electron is equal to 9.10938 × 10e–31 kg, the speed of light (c) is equal to 3.00 × 10e8 m/s, and Planck's constant is h = 6.626 × 10e–34. The velocity of these electrons is 297,196,680.87m/s
What is velocity ?The term velocity is defined as the direction of the movement of the body or the object. Speed is primarily a scalar quantity. Velocity is essentially a vector quantity.
We know the equation connecting potential and velocity of electrons is as follows,
eV=12mv2
Where eV is the kinetic energy
Also, we know
According to Einstein equation and de broglie equation we can write
mc2=hc
So,
mc = h
Given
me = 9.10938 × 10e
c = 3.00 × 10e8 m/s
h = 6.626 × 10e–34
λ = h / mc
= 2.45 × 20 ⁻¹²m
λ = h / mv
v = 297,196,680.87m/s
Thus, the velocity of these electrons is 297,196,680.87m/s
To learn more about the velocity, follow the link;
https://brainly.com/question/18084516
#SPJ1
How many quarters do you need to do 10 loads of laundry?
This depends how much it costs per load of laundry.
For example:
If 1 load of laundry costs $2.50, this would mean that you need 10 quarters for one load. Multiply that by 10, and you get 100 quarters (the equivalent of $25).
Depending on how much the load costs, simply divide the price per load by .25 to get you total in quarters, then multiply it by 10 in this case.
chemical name of this formula Na2SO4.
Na is for sodium and SO4 is sulfate...
Answer: The chemical compound name for Na₂SO₄ is Sodium Sulfate.
Balsa wood has a typical density of 140kg/m^3 . What is the volume of a piece of balsa wood weighing 50lbs?
The volume of the balsa wood weighing 50lbs is approximately 0.162 cubic meters.
What is volume?Volume is defined as the space occupied within the boundaries of an object in three-dimensional space.
To find the volume of a piece of balsa wood weighing 50lbs, we need to first convert the weight to kilograms and then divide by the density of balsa wood.
1 lb = 0.45359237 kg
So, 50 lbs = 50 * 0.45359237 = 22.6796185 kg
The volume of the balsa wood can then be calculated as follows:
Volume = 22.6796185 kg / (140 kg/m^3) = 0.162 m^3
Therefore, The volume of the balsa wood weighing 50lbs is approximately 0.162 cubic meters.
Learn more about volume here: brainly.com/question/14197390
#SPJ1
The pressure of a gas sample at 37.0 °C is increased from 1.10 atm to 2.30 atm by heating at a constant volume. What is the temperature (in °C) of the gas at 2.30 atm?
Considering the Gay Lussac's Law, the the temperature of the gas at 2.30 atm is 375.18 °C.
Definition of Gay Lussac's LawGay Lussac's Law establishes the relationship between the pressure and temperature of a gas when the volume is constant.
This law establishes that the pressure of the gas is directly proportional to its temperature because as the temperature increases the gas molecules move faster and therefore the number of collisions against the walls increases. In other words, the pressure increases since the container has fixed walls.
Mathematically, Gay Lussac's Law says that the ratio between pressure and temperature is constant:
P÷T=k
where
P is the pressure.T is the temperature.k is a constant.Analyzing an initial state 1 and a final state 2, it is fulfilled:
P₁÷T₁=P₂÷T₂
Temperature at 2.30 atmIn this case, you know:
P₁= 1.10 atmT₁= 37 °C= 310 K (being 0°C= 273 K)P₂= 2.30 atm T₂= ?Replacing in Gay Lussac's law:
1.10 atm÷ 310 K= 2.30 atm÷T₂
Solving:
(1.10 atm÷ 310 K)×T₂= 2.30 atm
T₂= 2.30 atm÷ (1.10 atm÷ 310 K)
T₂= 648.18 K= 375.18 °C
Finally, the final temperature is 375.18 °C.
Learn more about Gay Lussac' Law:
https://brainly.com/question/4147359
#SPJ1
HELP PLEASEEE!!!!!!!!!!!!!!!!!!!!!!!!!!!
Answer:
weathering
Explanation:
This is typical erosion of rocks / soil etc caused by wind/rain/ice etc
How do I draw the Lewis structure ?
Find out how many valence electrons there are in total. Step 2: Write down the molecule's skeleton structure. Step 3: Each bond in the skeleton structure is formed by using two valence electrons.
How should I depict the Lewis structure?First, the sum of the valencies of each atom determines the total number of valence electrons in the molecule.
The Lewis dot structure gains electrons (number of electrons added equals magnitude of negative charge) if the molecule is an anion.
A Lewis electron dot diagram, also known as an electron dot diagram, Lewis diagram, or Lewis structure, is a way to show the valence electrons in an atom by placing dots around the symbol for the element. The number of valence electrons in the atom is depicted by the diagram's number of dots. The atom symbol is surrounded by dots that represent the electrons in the outer shell. These symbols are referred to as Lewis symbols and electron dot symbols.
Learn more about lewis structure:
brainly.com/question/28384183
#SPJ1
HElppppppp!!!!!!!!!!!!!!!!!!!!!!!
Answer:
The edges changes quite drastically and the size went down by a millimeter. The color and hardness didn't change at all. The most noticeable difference was the edges.
4. Which formula represents the binary molecular compound dinitrogen tetroxide?
O N₂0
ON₂04
O NO4
O N₂02
N₂0₄ is the formula represents the binary molecular compound dinitrogen tetroxide. Therefore, option B is correct.
What is the binary molecular compound ?Binary molecular compounds are made up of exactly two nonmetal elements. HF, NO2, and P2O5 are a few examples. It is extremely simple to name binary molecular compounds. The first element is given its element name, followed by ide; the second element is given its root (hydr, bor, carb, ox, fluor, etc.).
In N₂0₄ molecule there are two nitrogen atoms at the suffix so, it is binary and in oxygen atom its suffix is 4 so, it is tetroxide. Therefore, N₂0₄ is the formula represents the binary molecular compound dinitrogen tetroxide.
Thus, option B is correct.
To learn more about the binary molecular compound, follow the link;
https://brainly.com/question/7960132
#SPJ1
what volume of water should be added to 150cm3 of 0.5M NaOH to produce 0.1M solution
Taking into account the definition of dilution, the volume of water added to 150cm³ of 0.5 M NaOH to produce 0.1 M solution is 600 cm³.
Definition of dilutionA dilution is a procedure whose purpose is to decrease the amount of solute per unit volume of dilution. This procedure is accomplished by adding a specified amount of diluent to a specified amount of solute.
The amount of solute does not change. As more solvent is added, the concentration of the solute decreases and the volume of the solution increases.
A dilution is mathematically expressed as:
Ci×Vi = Cf×Vf
where:
Ci: initial concentrationVi: initial volumeCf: final concentrationVf: final volumeVolume of water addedIn this case, you know:
Ci= 0.50 MVi= 150 cm³Cf= 0.10 MVf= ?Replacing in the definition of dilution:
0.50 M× 150 cm³= 0.10 M× Vf
Solving:
(0.50 M× 150 cm³)÷ 0.10 M= Vf
750 cm³= Vf
If the initial volume is 150 cm³, the amount of volume of water added is calculated as:
Volume of water= Vf - Vi
Volume of water= 750 cm³ - 150 cm³
Volume of water= 600 cm³
In summary, the volume of water added is 600 cm³.
Learn more about dilution:
brainly.com/question/6692004
#SPJ1
A 76.00 pound flask of mercury costs $142.00. The density of mercury is 13.534 g/cm3. Find the price of one cubic inch of mercury by calculating intermediate values. What is the price of one pound of mercury?
The cost of 1 pound flask of mercury is $1.86. One of the most commonly used units for determining the mass or substance of an item or a body is the pound.
What is pound?You really must understand what pounds signify when referring to weight. One of the most commonly used units for determining the mass or substance of an item or a body is the pound.
Scales are used in several ways to determine a body's weight or mass. To measure various items of various sizes, many sorts of scales are utilized. As the measure of an object's weight, pounds are used. In Britain, this style of measuring in pounds is typical.
cost of 76.00 pound flask of mercury =$142.00
cost of 1 pound flask of mercury=$142.00/ 76.00 =$1.86
Therefore, the cost of 1 pound flask of mercury is $1.86.
To learn more about pound, here:
https://brainly.com/question/29181271
#SPJ1
Explain the relationships between mass % of sugar and density
The mass percent of the sugar would increase as the density is increasing.
What is the relationships between mass % of sugar and density?There is a positive relationship between the mass percent of sugar and the density of a sugar solution. As the mass percent of sugar in a solution increases, the density of the solution also increases
. This occurs because sugar molecules have mass, and when more sugar is added to a solution, the total mass of the solution increases, resulting in a higher density. However, it is important to note that the relationship between the mass percent of sugar and density is not linear and is influenced by the temperature and pressure of the solution.
Learn more about density:https://brainly.com/question/29775886
#SPJ1
HELPPP PLEASEEEEE!!!!!!!
The evidence in figure 2 and table 1 which describes the changes in the rock after a year is the presence of a round edge.
What is Weathering?This is referred to as the breaking down or dissolving of rocks and minerals on Earths surface through elements such as wind, water etc.
In the diagram given, the rock previously had a sharp edge but as time went on there was breakdown of the edges which resulted in it becoming round and is therefore the evidence that weathering most likely occurred in the rock.
Read more about Weathering here https://brainly.com/question/829782
#SPJ1
The molar mass of KCI is 74.55 g/mol.
What is the mass of 0.359 mol KCI?
[?]g KCI
Mass of 0.359 mol of KCI is calculated to be 26.79 g. Mass of a given chemical element or chemical compound (g) divided by the amount of substance (mol) is called molar mass.
What is meant by molar mass?Molar mass of a compound can be calculated by adding standard atomic masses of the constituent atoms.
The mass of 0.359 mol of KCI can be calculated by multiplying the number of moles by its molar mass:
mass = moles * molar mass
mass = 0.359 mol * 74.55 g/mol
mass = 26.79 g
So, the mass of 0.359 mol of KCI is 26.79 g.
To know more about molar mass, refer
https://brainly.com/question/837939
#SPJ1
Answer: 26.79
Explanation:
Gaseous iodine pentafluoride, IF₅, can be prepared by the reaction of solid iodine and gaseous fluorine: I₂(s) + 5F₂(g) → 2IF₅(g) A 10.00 L flask is charged with 15.0 grams of I₂ and 2.00 atm of F₂ at 25 °C. The flask is heated to 100 °C until one of the reagents is completely consumed. What will be the percentage of IF₅ (by mole) in the final product mixture? (Assume ideal gas behavior).
Answer:
The percentage of IF₅ (by mole) in the final product mixture will be 50%. This is determined by the stoichiometry of the reaction, the given molar mass of the reactants, and the ideal gas law.
Explanation:
What are some hazards to be aware of in this lab?
flammable substances
sharps (equipment that can cut or puncture skin)
natural gas
electricity
fire
extreme cold
distilled (aka de-ionized or DI) water
acid
Some of the hazards that we should be aware of in the laboratory include the following: flammable substances, sharps (equipment that can cut or puncture skin) and fire. That is option A, B and E.
What are laboratory hazards?Laboratory hazards are those substances or equipments that are found in the laboratory which can cause harm to an individuals working in the laboratory.
Some of the hazards in the laboratory include chemical, biological, physical and radioactive hazards, as well as, musculoskeletal stresses.
Learn more about hazards here:
https://brainly.com/question/29546272
#SPJ1
Some of the hazards to be aware of in this lab include;
flammable substancessharps (equipment that can cut or puncture skin)fireacidWhat are the hazards in a laboratory?A Laboratory hazard is anything that has the potential to cause damage or harm.
Chemical, biological, physical, radioactive, and other possible risks are all present for those working in a laboratory, in addition to musculoskeletal strains. Many employees are more likely to sustain injuries because they are not aware of the dangers that could exist at work.
Some laboratory hazards include:
PoisoningFire HazardsSharp ObjectsStovesLearn more about laboratory hazards at: https://brainly.com/question/30369561
#SPJ1
which of the following cannot be a chemical symbol of an element
Cf cannot be a chemical symbol of an element. Therefore, option B is correct.
What is an element ?The term an element is defined as a substance that cannot be broken down into a simpler format. They are separate by a unequaled atomic number. The elements are formed by their atomic number in the periodic table, which highlights elements with similar properties.
Cf cannot be a chemical symbol of an element. CO is the symbol of element cobalt. B is the symbol of element boron and Cu is the symbol of an element copper.
Thus, option B is correct.
To learn more about an element, follow the link;
https://brainly.com/question/13025901
#SPJ1
Your question is incomplete, most probably your answer was
Which of the following cannot be the chemical symbol for an element
a. co
b. cf
c. b
d. cu
A sample of trifluoroacetic acid, C2HF3O2, contains 47.3 g of oxygen. Calculate the mass of the trifluoroacetic acid sample.
Based on the percentage mass of oxygen in trifluoroacetic acid, the mass of the trifluoroacetic acid sample is 168.5 grams.
What is the percentage mass of oxygen in trifluoroacetic acid?The percentage mass of oxygen in trifluoroacetic acid is determined as follows:
The molar mass of trifluoroacetic acid = 12 * 2 + 1 + 19 * 3 + 16 * 2
The molar mass of trifluoroacetic acid = 114 g
The percentage mass of oxygen in trifluoroacetic acid = (16 * 2)/114 * 100%
The percentage mass of oxygen in trifluoroacetic acid = 28.07%
The mass of the trifluoroacetic acid sample will be 47.3/ 28.07% = 168.5 grams
Learn more about percentage mass at: https://brainly.com/question/26150306
#SPJ1
A reaction has a rate constant of 0.0017/s at 400.0 K and 0.689/s at 450.0 K.
a. Determine the activation barrier for the reaction.
b. What is the value of the rate constant at 425 K?
The molecules mix more slowly in a low-rate reaction than they do in an elevated reaction. Therefore, the activation barrier for the reaction is 122 kJ.
What is rate of reaction?The change in concentration of each of the products or reactants each unit of time is referred to as the rate of reaction. The pace that a chemical reaction takes place is known as the reaction rate. The molecules mix more slowly in a low-rate reaction than they do in an elevated reaction.
log(k[tex]_2[/tex] / k[tex]_1[/tex])=(-Ea/R)×(1/T[tex]_1[/tex]-1/T[tex]_2[/tex])
Where,
k[tex]_1[/tex] = 0.0117 s-1
k[tex]_2[/tex]= 0.689 s-1
T[tex]_1[/tex] = 400.0 k
T[tex]_2[/tex] = 450.0 k
R is the ideal gas constant
R = 8.314 KJ / (Kmol * K)
Substituting all the given values, we get
ln (0.0117/0.689)=-Ea/(8.314)*((1/400)-(1/450))
Ea = 122 kJ
Therefore, the activation barrier for the reaction is 122 kJ.
To learn more about rate of reaction, here:
https://brainly.com/question/12920261
#SPJ1
More molecules in a fixed volume means
pressure.
less
more
More molecules in a fixed volume means more pressure.
What is a Molecule?According to the context, the term may or may not include ions that meet this requirement. A molecule is a collection of two or more atoms held together by attractive forces known as chemical bonds.
Hence, it can be seen that an increase in the number of gas molecules, while container volume stays constant, increases pressure.
A decrease in container volume increases gas pressure. An increase in the temperature of a gas in a rigid container increases the pressure
Read more about molecules here:
https://brainly.com/question/26044300
#SPJ1
What was Flint’s response to the Virginia Tech research findings?
State of emergency was proclaimed in Flint, the county seat of Genesee, by Michigan Governor Rick Snyder on January 5, 2016. Shortly after, President Barack Obama announced a federal state of emergency, approving further assistance from the Department of Homeland Security and the Federal Emergency Management Agency.
What is the Flint water crisis?A public health emergency known as the Flint water crisis began in 2014 when the drinking water in Flint, Michigan was found to be tainted with lead and possibly Legionella bacteria. Flint switched its water source from treated Detroit Water and Sewerage Department water (obtained from Lake Huron and the Detroit River) to the Flint River in April 2014 due to a budget issue.
Learn more Flint water crisis here https://brainly.com/question/20987410
#SPJ1
3. Record your observations for each simulation test trial in the tables below and write 3-4 sentences describing your observations.
(Hint: Simulation is in lesson 1.16)
Choose a different starting number of carnivores, herbivores, and producers for each trial you conduct.
Table 1: Test Trial 1
Organisms in Simulation Start (number you added of each) End (number you ended with)
Carnivore
Herbivore
Producer
Table 2: Test Trial 2
Organisms in Simulation Start (number you added of each) End (number you ended with)
Carnivore
Herbivore
Producer
Table 3: Test Trial 3
Organisms in Simulation Start (number you added of each) End (number you ended with)
Carnivore
Herbivore
Producer
Write 3-4 sentences describing your observations in the three tables above.
4. What conclusions can you draw about how resource availability affects populations of organisms in an ecosystem? Write an evidence-based claim. (Hint: This means you state whether your hypothesis/prediction is correct or incorrect. You then need to provide evidence from your observation tables to support your claim of it being correct/incorrect.)
The abundance of resources means that there would be more individuals in the ecosystem.
What is the effect of availability of resources on the ecosystem?When resources are abundant, competition for those resources is less intense. However, when resources become scarce, competition for them increases, and some species may become extinct or be displaced by more competitive species.
Again, availability of resources can also affect population growth. For example, if resources are abundant, populations of organisms may increase, leading to overcrowding and competition for limited resources. On the other hand, if resources are scarce, population growth may be limited.
Learn more about ecosystem:https://brainly.com/question/13979184?
#SPJ1
118Sn 117.90 47.%
119Sn 118.90 53.%
Use these measurements to complete the entry for tin in the Periodic Table that would be used on 98765 ALEKS. Round your entry for the atomic mass to 3 significant digits.
___
Sn
___
The average atomic mass of tin is 118.
What is the relative atomic mass of tin?The average atomic mass of an element can be calculated by taking into account the isotopic composition of the element and the atomic masses of its isotopes. The average atomic mass is found by weighting the atomic masses of each isotope with its relative abundance, and then summing these values.
Average atomic mass = (mass of isotope 1 * abundance of isotope 1) + (mass of isotope 2 * abundance of isotope 2) + ... + (mass of isotope n * abundance of isotope n)
For the average atomic mas of tin;
(117.9 * 0.47) + (118.9 * 0.53) =
55.4 + 63.0
= 118.4
Learn more about atomic mass:https://brainly.com/question/17067547
#SPJ1
Pls answer the question OR ELSE... You will step in a huge pile of gum, thereby ruining your shoes!
This is what you call a reactant that you have enough of. The one that DOES NOT run out.
Question 2 options:
Excess Reactant
Limiting Reactant
Answer:
Excess Reactant
Explanation:
Limiting Reactant is the reactant the runs out first.
NEED HELP WITH CHEMISTRY ASAP
Answer:
Below
Explanation:
a) From the equation every 2 moles of (CuNo3)2 results in ONE mole of O2
starting with 5 moles you would get 2 1/2 moles of O2
each mole of O2 weighs ( 2 * 15.99) = 31.98 g ( from periodic table)
2 1/2 of these would weigh 79.95 g
b) each mole of Cu(NO3)2 produces the same number of moles of Cu O
how many moles of Cu (NO3)2 are in 87.49 g
again from periodic table Cu = 63.546 gm N = 14.007 O=15.999
total mole weight of Cu(No3)2 would then be 187.554 g
87.49 g / 187.554 g / mole = .466 moles the same amount of Cu O
c) Want to try this one yourself?
What are the molecular weights of the following compounds? 1. MgCl₂ 2. (NH4)SO4
The molar mass of compound of magnesium chloride is 95.211 g/mole while that of ammonium sulfate is 132.14 g/mole.
What is molar mass?Molar mass of a compound or a molecule is defined as the mass of the elements which are present in it.The molar mass is considered to be a bulk quantity not a molecular quantity. It is often an average of the of the masses at many instances.
The molecular mass and formula mass are used as synonym for the molar mass.It does not depend on the amount of substance which is present in the sample.It has units of gram/mole.
Learn more about molar mass,here:
https://brainly.com/question/12127540
#SPJ1
A particular frost-free refrigerator uses about 795 kWh of electrical energy per year. Express this amount of energy in J, kJ , and Cal.
The amount of energy used by the refrigerator is given in J, kJ, and Cal as follows:
In J = 2.862 * 10⁹ JIn kJ = 2.862 * 10⁶ KJIn cal = 6.86 * 10⁸ calWhat is the conversion factor from kilowatt-hour (kWh) to Joules (J)?The conversion factor from kilowatt-hours to joules is given below:
1 kWh = 1000 * 3600 J
1 kWh = 3600000 J
The energy used by the frost-free refrigerator is given below as follows:
795 kWh = 795 * 3600000 J
795 kWh = 2.862 * 10⁹ J
795 kWh = 2.862 * 10⁹ J / 1k/J
795 kWh = 2.862 * 10⁶ KJ
1 Joule = 0.24 Cal
2.862 * 10⁹ J = 2.862 * 10⁹ J * 0.24 cal/J
2.862 * 10⁹ J = 6.86 * 10⁸ cal
Learn more about calories and Joules at: https://brainly.com/question/30193709
#SPJ1
If 99.7632 g of boiling water are added at a temperature of 100.79°C. how much heat (in J) will have been released to the solution in the calorimeter when the solution reaches equilibrium at 64.4°C? (5 sf) (Hint: I'm asking you to calculate qhot for this exothermic process).
The reaction is exothermic and the heat that is released is exothermic reaction.
What is the heat that is released?We have to note that we can say that the reaction is an exothermic reaction when there is the release of heat in the system and then we know that the release of the heat would determine the equilibrium temperature.
We know that;
H = mcdT
m = mass of the water
c = Heat capacity of the water
dT = temperature change
We then have that;
H = 99.7632 * 4.2 * (64.4 - 100.79)
H = -15.2 kJ
Learn more about exothermic reaction:https://brainly.com/question/10373907
#SPJ1
5.6 mol N₂O.
Express your answer using two significant figures.
5.6 mol N₂O is equal to 5.6 mol. (Note: The chemical formula N₂O already specifies the number of moles, so including "mol" after the number is redundant.) The answer, rounded to two significant figures, is 5.6 mol.
What is 1 Mole?A mole is a unit of measurement in chemistry that represents an amount of a substance. One mole is defined as the amount of a substance that contains Avogadro's number of entities, where Avogadro's number is defined as 6.02214076 x 10²³ particles. This number is used to convert between mass, number of particles, and moles of a substance.
For example, one mole of a pure substance contains 6.022 x 10²³atoms, molecules, or ions, depending on the nature of the substance. The mole is a useful way to measure large amounts of chemical substances while avoiding the use of cumbersome numbers.
To know more about Avogadro's number, visit:
https://brainly.com/question/28812626
#SPJ1
The amount of energy required to change 20g of water to steam is +150 KJ/mol. Calculate the standard heat of vaporization of water.
The amount of energy required to change 20g of water to steam is +150 KJ/mol. The standard heat of vaporization of water is 7.5 KJ/mol.
What is heat of vaporization ?The amount of energy required to convert a liquid to a vapour at constant temperature and pressure is known as latent heat. The heat of fusion is the energy required to convert a solid to a liquid, and the heat of sublimation is the energy required to convert a solid to a gas.
Given:
q = 150 KJ/mol.
m = 20gram
The standard heat of vaporization of water is calculated by given formula
Hv = q / m
Where,
Hv is heat of vaporization of water
q is heat energy
m is mass
By substituting given value in equation we get,
Hv = 150 / 20
= 7.5 KJ/mol
Thus, the standard heat of vaporization of water is 7.5 KJ/mol.
To learn more about the heat of vaporization, follow the link;
https://brainly.com/question/11084176
#SPJ1