Answer:
NH3 is the molecular formula of ammonia
Explanation:
i hope this will help you :)
Which statement correctly describes a feature of the rock cycle?
PA
Rocks are preserved through the process.
Rocks change from one type to another.
Different rock groups are not related to one another.
Rocks change from one type to another in a specific order.
Answer:
It’s D
Explanation:
Answer:
D Rocks change from one type to another in a specific order.
Explanation:
En la electrólisis del Cloruro de plomo se han depositado 2.6 gramos del metal en 20 minutos el peso atómico del plomo es 206 calculo la intensidad de la corriente eléctrica empleada AYUDENNNNN PLISSSS es para hoy!!!!!
Answer:
2.01 A
Explanation:
Para esta pregunta debemos empezar por la semi-reaccion del plomo:
[tex]Pb^+^2~_(_a_q_)~+~2e^-~->~Pb_(_s_)[/tex]
Se intercambian dos electrones en la semi-reacción del plomo. Si tenemos en cuenta la ecuación:
[tex]n=\frac{I*t}{z*F}[/tex]
Donde:
n= Moles depositados
I= Intensidad de corriente (en Amperios)
z= Numero de electrones intercambiados
F= Constante de faraday = 96484 C/mol
t=tiempo (en segundos)
Que conocemos de esta ecuación?
Los moles (se pueden calcular a partir de la masa atómica del plomo, 207.2 g/mol)
[tex]2.6~g~Pb\frac{1~mol~Pb}{207.2~g~Pb}=0.0125~mol~Pb[/tex]
El tiempo (hay que convertirlo a segundos):
[tex]20~min\frac{60~s}{1~min}=1200~s[/tex]
Z (Numero de electrones)
De acuerdo a la semi-reacción son intercambiados 2 electrones.
Por lo tanto podemos resolver para "I":
[tex]I=\frac{n*z*F}{t}=\frac{0.0125~mol*2*96484\frac{C}{mol}}{1200~s}[/tex]
[tex]I~=~2.01~\frac{C}{s}=2.01~A[/tex]
Espero que sea de ayuda!
Which part of the electromagnetic spectrum is nearest to X-rays? microwaves infrared light gamma rays radio waves
Answer:
The correct answer to the following question will be Option A (Microwaves).
Explanation:
This tends to be a source of radiation, including some signals, infrared radiation, x-rays as well as gamma. This appears to have a diverse variety of uses, involving communications, radar, and scheduling, but best known by most individual people. Sections of society used handheld devices, including tablets, as well as WiFi.The other given choices are not related to the given circumstances. So that option A seems to be the appropriate one.
Answer:
its a
Explanation:
Which example is a long-term environmental change? La Niña El Niño climate change small asteroid impact
The correct answer is C. Climate change
Explanation:
Long-term environmental changes occur as major events affect the environment and ecosystems indefinitely. These events differ from short-term environmental changes because the effect of short-term environmental changes is mainly temporary. Also, long-term changes are usually gradual.
Climate change is an example of long-term environmental changes because this implies indefinite and major changes in weather patterns and ecosystems. For example, it is believed climate change will decrease the amount of ice in Earth, change sea level, and lead to the extinction of dozens of species. This does not occur with events such as el niño or a small asteroid impact that affect the environment for a short time and do not imply major changes.
Answer:
it is c) climate change
Explanation:
i just took the quiz
hope this helps!!! :D
which of the following us not a property of salt in the ionic and covalent properties lab
Explanation:
I think Low melting point
because NaCl (salt has mp 801 degC)
Water has mp 0 degC
Fredo’s spaceship takes him to the very edge of known space. There, gravity has no effect at all. Fredo takes a baseball and tosses it into space. What will most likely happen to the ball? It will not move at all. It will return to Fredo’s spaceship. It will eventually stop moving. It will continue moving in a straight line.
Answer:
D. It will continue moving in a straight line.
Explanation:
When Fredo takes a ball and tosses it into space, the ball will move upward infinitely.
Gravity is the downward force that acts on an object.
Without gravity, or without the effect of gravity, an object will continue to move in its path with the original direction applied to it.
Answer:
D
Explanation:
I took the test
What biological sample do home pregnancy tests use to detect pregnancy?
Answer:
The biological sample that pregnancy tests use to detect pregnancy is urine
Answer:
yes
Explanation:
the urine in the the tester will find hormones to determine if pregnant or not
a heating fan is supplied with 150 j of electricity which is nonverts to 113 j of thermal energy and 37 j of sound energy
How efficient is the heating fan?
Answer:
Heating Fan is 75.33% efficient.
Explanation:
As it is mentioned that the given fan is a HEATING FAN, it means the it is used for provided heat (thermal energy) to the surrounding. Hence, its efficiency depends upon how much heat/thermal energy is provides.
We can state that.
Total Energy provided = 150 J
Useful Energy = 113 J
Wasted Energy = 37 J
The efficiency of the heating fan can be given by following formula:
Efficiency = ( Useful Energy / Total Energy ) × 100
Efficiency = ( 113 J / 150 J) × 100
Efficiency = (0.7533)× 100
Efficiency = 75.33%
A 75 lb (34 kg) boy falls out of a tree from a height of 10 ft (3 m). i. What is the kinetic energy of the boy when he hits the ground? Round your answer to the nearest joule. ii. What is the speed of the boy when he hits the ground? Round your answer to two significant figures. iii. Using the conversion factors of 1 m = 1.094 yd and 1 mi = 1760 yd, calculate the speed of the boy in miles per hour when he hits the ground.
Answer:
Kinetic energy of boy just before hitting the ground is [tex]\approx[/tex]1000 J.
Speed of boy just before hitting the ground is 7.67 m/s
or 17.16 mi/hr.
Explanation:
Given that:
Mass of boy = 75lb = 34 kg
Height, h = 10ft = 3m
To find:
Kinetic energy of boy when he hits the ground.
As per law of conservation of energy The potential energy gets converted to kinetic energy.
[tex]\therefore[/tex] Kinetic energy at the time boy hits the ground = Initial potential energy of the boy when he was at the Height 'h'
The formula for potential energy is given as:
[tex]PE = mgh[/tex]
Where m is the mass
g is the acceleration due to gravity, g = 9.8 [tex]m/s^2[/tex]
h is the height of object
Putting all the values:
PE = [tex]34 \times 9.8 \times 3 \approx 1000\ J[/tex]
Hence, Kinetic energy is [tex]\approx[/tex]1000 J.
Formula for Kinetic energy is:
[tex]KE = \dfrac{1}{2}mv^2[/tex]
where m is the mass and
v is the speed
Putting the values and finding v:
[tex]1000 = \dfrac{1}{2}\times 34 \times v^2\\\Rightarrow v^2 = 58.82\\\Rightarrow v = 7.67\ m/s[/tex]
Given that:
1 m = 1.094 yd and 1 mi = 1760 yd
[tex]\Rightarrow 1609\ m = 1\ mi[/tex]
Converting 7.67 m/s to miles/hour:
[tex]\dfrac{7.67 \times 3600}{1609}=17.16\ mi/h[/tex]
c. Write a complete ionic equation for the reaction and identify the spectator ions.
The required complete ionic equation of the reaction
Pb(NO3)2+2KI---->PbI2+2KNO3 is Pb2+(aq) + 2 I−(aq) → PbI2(s)
What is ionic equation?A chemical equation in which the electrolytes in aqueous solution are expressed as dissociated ions.
Spectator ions in above equation are as follows- K +and NO3−
Define spectator ions.
Ions that are not involved in the actual chemical reaction are called spectator ions.
Net ionic equation of given reaction isPb⁺²+2I ⁻¹⟶PbI₂It shows only the ions which involves in the chemical reaction.
Therefore, K⁺ and NO3⁻ are spectator ions.
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Which of the following is the best definition of a physical change?
A. Something that can be observed or measured while changing the identity of the substance.
B. A nail rusting.
C. A change that occurs without changing the identity of the substance.
D. Ice melting into water.
Answer:
the answer is D.ice melting into water
Which refers to the density of the medium’s particles at the compression of a sound wave? A.amplitude B.pitch C.volume D.wavelength
Answer:
A is the answer.
Explanation:
The sound wave is a longitudinal wave which travels in the form of compression and rarefaction . The point where the particles are closer to each other is called compression and the point where the particles are far apart from each other is called rarefaction.
Answer:
Amplitude
Explanation:
Amplitude describes the displacement of the medium's particles. The higher the amplitude, the more dense it is, and the lower the amplitude, the less dense it is.
Pitch is incorrect because it describes the sound
Volume is incorrect because it describes the sound.
Wavelength is incorrect because it describes the distance between a period of a wave.
Which consists of only one type of atom?
Answer:
A chemical element
Explanation:
A chemical element consists of only one type of atom.
After 273 m3 of ethylene oxide at 748 kPa and 525 K is cooled to 293 K, it is allowed to expand to 1100. m3. The new pressure is _____kPa
Answer:
[tex]\large \boxed{\text{104 kPa}}[/tex]
Explanation:
To solve this problem, we can use the Combined Gas Laws:
[tex]\dfrac{p_{1}V_{1} }{n_{1}T_{1}} = \dfrac{p_{2}V_{2} }{n_{2}T_{2}}[/tex]
Data:
p₁ = 748 kPa; V₁ = 273 m³; n₁ = n₁; T₁ = 525 K
p₂ = ?; V₂ = 1100. m³; n₂ = n₁; T₂ = 293 K
Calculations:
[tex]\begin{array}{rcl}\dfrac{p_{1}V_{1}}{n_{1} T_{1}} & = & \dfrac{p_{2}V_{2}}{n_{2} T_{2}}\\\\\dfrac{\text{748 kPa}\times \text{273 m}^{3}}{n _{1}\times \text{525 K}} & = &\dfrac{p_{2}\times \text{1100. m}^{3}}{n _{1}\times \text{293 K}}\\\\\text{390.0 kPa} & = &3.754{p_{2}}\\p_{2} & = & \dfrac{\text{390.0 kPa}}{3.754}\\\\ & = & \textbf{104 kPa} \\\end{array}\\\text{The new pressure is $\large \boxed{\textbf{104 kPa}}$}[/tex]
what is the molar mass of magnesium tartrate
Answer:
172.385 g/mol
Explanation:
Magnesium Tartrate is C4H4MgO6
C - 12.01 g/mol
H - 1.01 g/mol
Mg - 24.305 g/mol
O - 16.00 g/mol
12.01(4) + 1.01(4) + 24.305 + 16(6) = 172.385 g/mol
Answer:
172.38
Explanation:
[tex]C_4H_4MgO_6\\C=12.01\\H=1.01\\Mg=24.30\\O=16.00\\\\4(12.01)+4(1.01)+24.30+6(16.00)\\48.04+4.04+24.30+96\\=172.38[/tex]
C = 12.01
H=1.01
Mg=24.30
O =16.00
4(12.01)+4(1.01)+24.30+6(16.00)
48.04 +4.04+24.30+96
=172.38
For each of the compounds, find the length of the longest carbon chain in the box provided.
CH,
CH3 -CH2-CH2-CH2-CH-CH2-CH2 - CH2 - CH3
CH,CH,CH,
HC
CH-CH2-CH3
CH,CH.CHCCH,CH,CH,
1
CH2
H.C CH.CH
CH3
<
Answer:
In First compound the longest chain contains 7 C atoms.
In the Second compound the longest chain contains 9 C atoms.
In the Third compound the longest chin contains 7C atoms.
Explanation:
In first compound the longest chain contains 7 carbon atoms.In the second compound the longest chain contains 9 carbon atoms.In the third compound the longest chin contains 7 carbon atoms.
What is an atom?An atom is defined as the smallest unit of matter which forms an element. Every form of matter whether solid,liquid , gas consists of atoms . Each atom has a nucleus which is composed of protons and neutrons and shells in which the electrons revolve.
The protons are positively charged and neutrons are neutral and hence the nucleus is positively charged. The electrons which revolve around the nucleus are negatively charged and hence the atom as a whole is neutral and stable due to presence of oppositely charged particles.
Atoms of the same element are similar as they have number of sub- atomic particles which on combination do not alter the chemical properties of the substances.
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A student weighs out a 6.64 g sample of , transfers it to a 500. mL volumetric flask, adds enough water to dissolve it and then adds water to the 500. mL tick mark. What is the molarity of cobalt(II) fluoride in the resulting solution
Answer:
the molarity of cobalt(II) fluoride in the resulting solution is = 0.137 M
Explanation:
Given that :
a student dissolves 6.64 g of CoF₂ into 500 mL of water
volume of the solution(water) = 500 mL = 0.50 L
The standard molar mass of CoF₂ is 96.93 g/mol
number of moles of CoF₂ = mass of CoF₂/molar mass of CoF₂
number of moles of CoF₂ = 6.64 g/96.93 g/mol
number of moles of CoF₂ = 0.0685 mol
The molarity of any given substance is known to be as the number of moles of solute dissolved in one litre of solution.
Thus ;
Molarity of cobalt(II) fluoride CoF₂ in the resulting solution is = number of moles / Volume in (L)
Molarity of cobalt(II) fluoride CoF₂ = 0.0685 mol/ 0.50 L
= 0.137 M
Thus ; the molarity of cobalt(II) fluoride in the resulting solution is = 0.137 M
How many moles of silver are equivalent to 2.408 x 10^24 atoms
The mole is used to measure small particles like atoms and molecules. The 4 moles of silver is equivalent to [tex]\bold{2.408 x 10^2^4 }[/tex] atoms.
Given here,
The number of atoms
[tex]\bold{2.408 x 10^2^4 }[/tex]
Number of moles = ?
1 mol of substance = [tex]\bold{ 6.02 x10^2^3}[/tex]
Hence,
moles of silver,
[tex]\bold {= \dfrac {2.408 x 10^2^4 } { 6.02 x10^2^3} }}\\\\\bold {= 4 mol}[/tex]
Therefore, the 4 moles of silver is equivalent to [tex]\bold{2.408 x 10^2^4 }[/tex] atoms.
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What is the best definition of chemistry?
A. The study of mass, energy, and light
B. The study of life and energy
C. The study of experiments and theories
D. The study of matter, its properties, and its reactions
how many atoms are contained in 2.70g of aluminum provided that 32g of sulphur equals 6.02 × 10^(23)atoms
Answer:
[tex]1.63 \times {10}^{24} [/tex]
one atom of an element = 6.02 \times {10}^{23} atom
The mass of one atom of sulphur = 32g
The mass of one atom of aluminium = 27g
so one atom of aluminium = 6.02 \times {10}^{23}
27g of AL = 6.02 \times {10}^{23} atom
2.70g of AL = X atoms
Then you cross multiply ........
and get the answer
.
what is the mass of 1.5 mol of aluminum?
Answer:
40.47 g Al
Explanation:
In 1 mol of Al, there are 26.98 grams of Al, so Al is 26.98 g/mol.
Simply multiply 1.5 by 26.98 to get your answer.
An aqueous solution of glucose (MM = 180.2 g/mol) has a molality of 2.27 m and a density of 1.20 g/mL. What is the molarity of glucose in the solution?
**Any help would be greatly appreciated!**
Answer:
Molarity of the glucose solution = 2.72 mol/L
Explanation:
Molality of a solution is defined as the number of moles of solute per kilogram of solvent.
Therefore , a 2.27 molal solution of glucose contains 2.27 moles of glucose in 1 Kg of solvent
Density of solution = 1.20 g/mL
The volume occupied by 1 Kg or 1000 g solution = mass/density
Volume of 1000 g solution = 1000 g/1.20 g/ml = 833.3 mL
Number of moles of glucose present in the solution = 2.27 moles
Molarity = number of moles / volume(L)
volume of solution in litres = 883.3/1000 = 0.8333 L
Molarity = 2.27 moles /0.8333 l = 2.72 mol/L
Therefore, molarity of the glucose solution = 2.72 mol/L
The molarity of the glucose in the solution has been 2.72 mol/L.
Molality can be defined as the moles of the solute per kg of solvent.
The molality of glucose solution = 2.27 m
2.27 moles of glucose in 1000 grams of water.
Density has been the mass per unit volume. The density can be expressed as:
Density = [tex]\rm \dfrac{Mass}{Volume}[/tex]
The density of the given glucose solution = 1.20 g/ml
The volume of 1000 grams of water has been:
Volume = [tex]\rm \dfrac{Mass}{Density}[/tex]
Volume of 1000 grams water = [tex]\rm \dfrac{1000\;g}{1.20\;g/ml}[/tex]
Volume of 1000 g water = 833.3 ml
The molarity can be defined as the mass of solute per liter of the solution.
Molarity = [tex]\rm moles\;\times\;\dfrac{1000}{Volume\;(ml)}[/tex] ......(i)
The moles of glucose in the 833.3 ml solution have been 2.27 mol.
Substituting the values in equation (i):
Molarity = 2.27 mol [tex]\rm \times\;\dfrac{1000}{833.3\;ml}[/tex]
Molarity = 2.72 mol/L.
The molarity of the glucose in the solution has been 2.72 mol/L.
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what is Lfusion in the equation Q=mLfusion
Answer:
[tex]L_{\text{fusion}[/tex] is latent heat of fusion.
Explanation:
Latent heat is basically termed as hidden heat. It is defined as the amount of heat required to change 1 g of a substance at the temperature of its melting point from the solid to the liquid state at constant temperature.The formula that relates heat and latent heat of fusion is given by :[tex]Q=mL_{\text{fusion}}[/tex]
Here,
m is mass of substance
[tex]L_{\text{fusion}[/tex] is latent heat of fusion.
Consider an electrochemical cell based on the spontaneous reaction 2AgCl(s) + Zn(s) → 2Ag(s) + 2Cl– + Zn2+. If the zinc ion concentration is kept constant at 1 M, and the chlorine ion concentration is decreased from 1 M to 0.001 M, the cell voltage should:
Answer:
there is an increase by 0.18 V in the cell voltage.
Explanation:
The given equation of the reaction can be well written as
[tex]2AgCl_{(s)} + Zn _{(s)} \to 2Ag_{(s)} + 2 Cl^- _{(aq)}+ Zn^{2+}_{(aq)}[/tex]
By application of Nernst Equation ; we have the expression
[tex]E_{cell} = E^0- \dfrac{0,059}{n}log (\dfrac{[product]}{[reactant]})[/tex]
here in the above equation;
n = number of electrons transferred in the equation of the reaction
n = 2
Also;
[tex]E^0 = E_{cathode} - E_{anode}[/tex]
[tex]E^0 = E_{Ag^+/Ag} - E_{Zn^+/Zn}[/tex]
[tex]E^0 = +(0.80 \ V) - (-0..76 \ V)[/tex]
[tex]E^0 = (0.80 \ V +0..76 \ V)[/tex]
[tex]E^0 = 1.56 \ V[/tex]
If the zinc ion concentration is kept constant at 1 M; we have:
[tex]E_{cell} = E^0- \dfrac{0.059}{n}log (\dfrac{[product]}{[reactant]})[/tex]
[tex]E_{cell} = 1.56 - \dfrac{0.059}{2}log ({[Zn^{2+} ]}{[Cl^{2-}]})[/tex]
[tex]E_{cell} = 1.56 - \dfrac{0.059}{2}log (1)[/tex]
Since log(1) = 0
Therefore;
[tex]E_{cell} = 1.56\ V[/tex]
When the chlorine ion concentration is decreased from 1 M to 0.001 M; we have;
[tex]E_{cell} = E^0- \dfrac{0.059}{n}log (\dfrac{[product]}{[reactant]})[/tex]
[tex]E_{cell} = 1.56 - \dfrac{0.059}{2}log ({[Zn^{2+} ]}{[Cl^{2-}]})[/tex]
[tex]E_{cell} = 1.56 - \dfrac{0.059}{2}log ({[1*0.001^2}]})[/tex]
[tex]E_{cell} = 1.56 - 0.0295 \ * \ log ({[1*10^{-6}}]})[/tex]
[tex]E_{cell} = + 1.737 \ V[/tex]
The change in voltage = [tex]E_{cell} - E^0[/tex]
=( 1.737 - 1.56 )V
= 0.177 V
≅ 0.18 V
Thus; from the following observation; there is an increase by 0.18 V in the cell voltage.
The voltage of the cell increased by 0.18 V.
The equation of the reaction is; 2AgCl(s) + Zn(s) → 2Ag(s) + 2Cl– + Zn2+
We know that;
E°cell = 1.36 - (-0.76) = 2.12 V
If the cells are both at 1M concentration the Ecell = E°cell = 2.12 V
When the concentration of Cl- decreased from 1 M to 0.001 M
Ecell = E°cell - 0.0592/n log Q
Substituting values;
Ecell = 2.12 V - 0.0592/2 log (1 × (0.001)^2)
Ecell = 2.298 V
Increase in voltage = 2.298 V - 2.12 V = 0.18 V
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Identify the correct statement regarding the strength of chemical bonds.
Weak bonds require more surface area to form than strong bonds.
A weak bond forms from a smaller change in energy compared to a strong bond.
Strong bonds occur with high temperature and weak bonds with low temperature.
Weak bonds require more heat to form than strong bonds.
Answer:
B.
Explanation:
A weak bond forms from a smaller change in energy compared to a strong bond.
Which is a negative effect of deforestation on the environment? habitat restoration, desertification, soil production, or urbanization
Answer:
The correct option is desertification
Explanation:
Deforestation is the deliberate act of pulling down trees to provide a clear land for space or to make use of the trees for other purposes such as grazing, farming, timber fire wood, building and constructions, urban utilization, access roads, expansion, development of infrastructures, grazing of cattle and mining
The effects of deforestation includes climate change, flooding, increase in the proportion of green house gases in the atmosphere, soil erosion and desertification.
A negative effect of deforestation is desertification.
Deforestation refers to the cutting down of trees. There are many reasons why people may cut down trees. One of the popular reasons why people cut down trees is to obtain timber which is used for construction and as fuel.
An important consequence of the felling of trees also called deforestation is that a once fertile land may gradually be turned into a desert area. This is known as desertification.
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Phloem contains specialized cells that move sugars and other nutrients both
up and down in plants. Which object is the best model of one of these cells?
A. Water balloon
Answer:Drinking straw
Explanation: my quiz said so
The object that represents the best model of one of the phloem cells is the drinking straw.
What is Phloem?Phloem may be defined as a type of vascular tissue in plants that significantly conducts the passage of sugars and other metabolic products from the leaves to the roots. This mediates the migration of sugar which is synthesized in the leaves during photosynthesis.
Apart from this, the phloem also regulates the movement of nutrients from the roots to the upper part of the body. This function of phloem cells shares homology with the object known as a drinking straw that mediates the transport of any fluid in both directions.
Therefore, a drinking straw is an object that represents the best model of one of the phloem cells.
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Your question seems incomplete. The most probable complete question is as follows:
Can openerWater balloonDrinking StrawKitchen strainerSet up the ion formation equations, with ionization energy values for each electron in the valence layer, of the atoms of the chemical elements below: a) Na z=11 b) Ca z= 20 c) Sr z 38 d) Li z= 3 e) Cs z= 55 f) Be z= 43
Answer:
according to quantum physics newtons 3rd law is in the state of nuclear power things so the answer is c
Explanation:
according to quantum physics newtons 3rd law is in the state of nuclear power things so the answer is c
what is meant by amoeba and what is the name of its parts
Answer:
amoeba is the unicellular organism which can be seen by only microscope but not with our nacked eyes
Answer:
An amoeba often called an amoeboid, is a type of cell or unicellular organism which has the ability to alter its shape, primarily by extending and retracting pseudopods Amoebae do not form a single taxonomic group; instead, they are found in every major lineage of eukaryotic organisms. Amoeboid cells occur not only among the protozoa, but also in fungi, algae, and animals.
name of parts of ameoba
3 parts – the cytoplasm, plasma membrane and the nucleus. The cytoplasm can be differentiated into 2 layers – the outer ectoplasm and the inner endoplasm. The plasma membrane is a very thin, double-layered membrane composed of protein and lipid molecule
i hope this will help you
Calculate the payback time if she insulates the loft with 300 mm insulation when: area of loft space = 100m^2 cost of roll of 100 mm thick loft insulation that covers 8.3m^2 = £20 cost of putting the insulation into the loft = £120 savings per year = £80 per 100 mm Payback Time = installation cost divided by annual savings
Answer: Payback time = 0.0075
Explanation: Since payback time is calculated as:
payback time = [tex]\frac{installation cost}{annual savings}[/tex]
First determine the installation cost:
100 mm thick insulation covers 8.3 m². Then 300 mm covers 24.9 m².
To cover 8.3m² costs £20. Then, the cost to cover 24.9 m² is:
cost = [tex]\frac{20*24.9}{8.3}[/tex]
cost = £60
The cost of putting the insulation is £120, so the total cost is:
total cost = £60 + £120
total cost = £180
Savings per year per 100 mm thick is £80. For 300 mm, the value of annual savings is:
savings = [tex]\frac{300*80}{100}[/tex]
savings = 240
payback time = [tex]\frac{installation cost}{annual savings}[/tex]
payback time = [tex]\frac{180}{240}[/tex]
payback time = 0.75