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.

Answers

Answer 1

Answer:

the answer is D.ice melting into water


Related Questions

15 Ethanoic acid reacts slowly with calcium carbonate.
Which statements explain why an increase in temperature increases the rate oft
1
The activation energy of the reaction is decreased.
2
There is an increase in collision rate.
3
The particles have more energy.
4
There will be fewer successful collisions.
А
1 and 2
B
1 and 3
с
2 and 3
D
2 and 4

Answers

Answer:

C

2and3

Explanation:

increase in temperature causes the particles to gain more energy

The answer is C. 2 and 3

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

Answers

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

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

Answers

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.

To learn more about Phloem cells, refer to the link:

https://brainly.com/question/3138900

#SPJ2

Your question seems incomplete. The most probable complete question is as follows:

Can openerWater balloonDrinking StrawKitchen strainer

At what angle(s) should investigators photograph a tool mark? A. parallel B. perpendicular C. 45 degrees D. varying

Answers

The answer is b. perpendicular

Answer:

B

Explanation:

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.

Answers

Answer:

B.

Explanation:

A weak bond forms from a smaller change in energy compared to a strong bond.

what is meant by amoeba and what is the name of its parts​

Answers

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

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:

Answers

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

Learn more: https://brainly.com/question/165414



Next, break down the equation shown into the skeletal half-reactions for oxidation and reduction. Which of
these pairs shows the two skeletal half-reactions with their correct assignments?
reduction half reaction: HNO, NO
oxidation half reaction SH,SO,
oxidation half reaction: HNO3 -> NO
reduction half reaction: SH2SO,
reduction half reaction: HNO3 -H,SO,
oxidation half reaction S -> H2SO4

Answers

Answer:

Its answer A

Explanation:

I just took the test

Answer:

A:

reduction half reaction: HNO3-> NO

oxidation half reaction S->H2SO4

Explanation:

What biological sample do home pregnancy tests use to detect pregnancy?

Answers

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 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.

Answers

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]

Primary succession is most likely caused by?

Answers

Answer:

volcanic eruption.

mark my answer as brainlest......

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
<​

Answers

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.

Learn more about atom,here:

https://brainly.com/question/13654549

#SPJ2

name the bleaching agent for cloth​

Answers

Hydrogen peroxide is one of the most common bleaching agents. It is the primary bleaching agent in the textile industry, and is also used in pulp, paper, and home laundry applications.

bleaching agent is a material that lightens or whitens a substrate through chemical reaction. The bleaching reactions usually involve oxidative or reductive processes that degrade color systems. These processes may involve the destruction or modification of chromophoric groups in the substrate as well as the degradation of color bodies into smaller, more soluble units that are more easily removed in the bleaching process. The most common bleaching agents generally fall into two categories: chlorine and its related compounds (such as sodium hypochlorite) and the peroxygen bleaching agents, such as hydrogen peroxide and sodium perborate. Reducing bleaches represent another category. Enzymes are a new category of bleaching agents. They are used for textile, paper, and pulp bleaching as well as for home laundering. Chlorine‐containing bleaching agents are the most cost‐effective bleaching agents known. They are also effective disinfectants, and water disinfection is often the largest use of many chlorine‐containing bleaching agents. They may be divided into four classes: chlorine, hypochlorites, N‐chloro compounds, and chlorine dioxide. Except to bleach wood pulp and flour, chlorine itself is rarely used as a bleaching agent. The principal form of hypochlorite produced is sodium hypochlorite. Other hypochlorites include calcium hypochlorite and bleach liquor, bleaching powder and tropical bleach. The principal solid chlorine bleaching agents are the chlorinated isocyanurates, eg, sodium dichloroisocyanurate dihydrate. Other N‐chloro compounds include halogenated hydantoins, and sodium N‐chlorobenzenesulfonamide (chloramine B). Chlorine dioxide is a gas that is more hazardous than chlorine. Large amounts for pulp bleaching are made by several processes in which sodium chlorate is reduced with chloride, methanol, or sulfur dioxide in highly acidic solutions by complex reactions. Hydrogen peroxide is one of the most common bleaching agents. It is the primary bleaching agent in the textile industry, and is also used in pulp, paper, and home laundry applications. Hydrogen peroxide reacts with many compounds, such as borates, carbonates, pyrophosphates, sulfates, etc, to give peroxy compounds or peroxyhydrates. Peracids have superior cold water bleaching capability versus hydrogen peroxide because of the greater electrophilicity of the peracid peroxygen moiety. Lower wash temperatures and phosphate reductions or bans in detergent systems account for the recent utilization and vast literature of peracids in textile bleaching. The reducing agents generally used in bleaching include sulfur dioxide, sulfurous acid, bisulfites, sulfites, hydrosulfite (dithionites), sodium sulfoxylate formaldehyde, and sodium borohydride. These materials are used mainly in pulp and textile bleaching.

ANSWER:
Hydrogen peroxide is one of the bleaching agents that is most commonly used worldwide.
HOPE IT HELPS!!!

How does the government control scientific research

Answers

Answer:

The government allocates a budget for research every year. The spending of that money is determined by government priorities. Some of the money is spent directly, in government-funded research centers.

Other money is distributed to other research institutions.

Money spent by other institutions for research has no government oversight.

Explanation:

You arrive at a crime scene and are told the body of the victim is in the 10 m deep pool. You walk over to what you are told is a 12 m in diameter, cylindrical pool. From the outside of the pool, you can see that the body looks badly burnt. Your partner says, “It looks like our victim had been burned alive and tried to put out the fire by jumping in the pool. The victim likely drowned to death.”

Something does not sit right with you though. If there was a fire, where did it start? There are no signs of combustion anywhere. You aren’t so sure and ask the crime scene investigator to run a sample of the pool water before letting anybody try to pull the body out.

The CSI comes back to you and tells you that normal pool water pH is roughly around 7.2, but the pool pH is actually highly basic at a level of 13 with a concentration of hydroxide ions at 1.0 x 10-1 mol/L. It becomes obvious to you that the body wasn’t burned before going in to the pool , but AFTER and there was no fire needed!

You order the body to be removed from the pool, but the CSI interjects, “It would be too dangerous with a pH that high. I suggest you get some vinegar from the store and pour it in to the pool before hand to drop the pH to 7. Draining the pool would take far too long and we need to examine the body as soon as possible.” She asks one of your constables to go to the store to purchase 5 – 4L jugs of vinegar (pH = 2) to pour in the pool, as she states it is enough to bring the pH to a safe level of 7.

It sounds like it could be enough vinegar based on your knowledge of acids and bases, but you want to double-check her estimate before sending your constable to the store. Verify whether or not she is correct using calculations. A diagram may help you with your calculations.

Hint 1: 1m3 = 1000L

Hint 2: Vcylinder = πr2h

Answers

Answer:

The vinegar is not enough to neutralize the pool.

Explanation:

The [OH⁻] in the pool is 1.0x10⁻¹mol / L. To know how many moles of OH⁻ are in the solution, you must calculate volume of the pool thus:

V(pool) = πr²h

Where r, radius is d/2 = 12m/2 = 6m  and h is deep of the pool = 10m

V(pool) = π(6m)²*10

V(pool) = 1131m³

As 1m³ = 1000L:

1131m³  × (1000L / 1m³) = 1131000L in the pool.

And moles of OH⁻ are:

1.0x10⁻¹mol / L ₓ 1131000L = 131100 moles of OH⁻ are in the pool

The neutralization of OH⁻ with H⁺ is:

OH⁻ + H⁺ → H₂O

That means to neutralize the pool you must add 131100 moles of H⁺.

The H⁺ concentration in a vinegar pH = 2 is:

pH = -log [H⁺]

2 = -log [H⁺]

1x10⁻²M = [H⁺]

4L are just 4x10⁻² moles of [H⁺]. As you need 131100 moles of H⁺:

The vinegar is not enough to neutralize the pool.

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

Answers

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.

what is the mass of 1.5 mol of aluminum?

Answers

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.

how many atoms are contained in 2.70g of aluminum provided that 32g of sulphur equals 6.02 × 10^(23)atoms​

Answers

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

.

which of the following us not a property of salt in the ionic and covalent properties lab

Answers

Explanation:

I think Low melting point

because NaCl (salt has mp 801 degC)

Water has mp 0 degC

Which consists of only one type of atom?

Answers

Answer:

A chemical element

Explanation:

A chemical element consists of only one type of atom.

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?

Answers

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%

Which part of the electromagnetic spectrum is nearest to X-rays? microwaves infrared light gamma rays radio waves

Answers

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:

what is Lfusion in the equation Q=mLfusion

Answers

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.

what is the molar mass of magnesium tartrate

Answers

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

Set 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

Answers

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

Which sequence represents the relationship between pressure and volume of an ideal gas as explained by the kinetic-molecular theory? more gas particles Right arrow. More collisions Right arrow. Higher pressure smaller volume Right arrow. Crowded particles Right arrow. Less collisions Right arrow. Lower pressure smaller volume Right arrow. Crowded particles Right arrow. More collisions Right arrow. Higher pressure more gas particles Right arrow. More kinetic energy Right arrow. More volume Right arrow. Higher pressure

Answers

Answer:

smaller volume ⇒ Crowded particles ⇒ More collisions  ⇒ Higher pressure

Explanation:

Smaller the volume , more crowed the particles . Then the particles will have rapid collisions so the free mean path is decreased , hence the pressure will be increased as follows

[tex]P=\frac{K_bT}{\sqrt{2}\pi d^2\lambda }[/tex]

where λ is mean free path , P is pressure .

The sequence the represent the relationship between pressure and volume of an ideal gas is: smaller volume right arrow Crowded particles right arrow More collisions right arrow Higher pressure

The kinetic molecular theory made five postulates which are used to explain the behaviour of gases.

From the postulates, he uses the kinetic molecular theory to explain Boyle's Law because the majority of a gas's volume in space is usually empty and may be compressed.

So, when a gas is compressed without affecting its temperature, the average kinetic energy of the gas particles remains constant. The particles continue to flow at the same rate, but the container has reduced.

As a result, the particles go from one end of the container to another in less time. This suggests they're hitting the barriers (collision) more frequently. Each and every increase in the frequency of collisions with the walls, thus, results in an increase in the gas's pressure.

Hence, as the volume of a gas decreases, the pressure of the gas increases.

Learn more about the Kinetic molecular theory here:

https://brainly.com/question/2901837

5.What is the chemibal formula for lead (II) iodide

Answers

Answer: The chemical formula for lead (II) iodide is [tex]PbI_2[/tex]

Explanation:

Lead (II) iodide is a ionic compound because it are formed by transference of electrons between metals and non metals.The bond formed between a metal and a non-metal is always ionic in nature.

For formation of a neutral ionic compound, the charges on cation and anion must be balanced. The cation is formed by loss of electrons by metals and anions are formed by gain of electrons by non metals.

The nomenclature of ionic compounds is given by:

1. Positive is written first followed by the oxidation state of metal in roman numerals in square brackets.

2. The negative ion is written next and a suffix is added at the end of the negative ion. The suffix written is '-ide'.

The chemical formula for lead (II) iodide is [tex]PbI_2[/tex]

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

Answers

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

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

Answers

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]

c. Write a complete ionic equation for the reaction and identify the spectator ions.

Answers

Answer is 6 Na + (aq) +3 CA swaured + 6 CI- (aq)

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.

Learn more about spectator ions ,here:

https://brainly.com/question/22277121

#SPJ2  

Other Questions
Determine the absolute maximum and minimum of f(x)= 2 cosx+ sin 2x The population of a town is 9,000, and it grows at a rate of 7% per year. What will the population be in 6 years? factor y=2x^2+10x+12 Which of the following describes the function of carbohydrates? A. Carbohydrates store hereditary information. B. Carbohydrates help leaves absorb the sun's energy. C. Carbohydrates surround and protect internal organs. D. Carbohydrates store energy in their bonds. It is 45C at sea level. What will the temperature be at 5500 meters? Use the normal lapse rate. Which equations represent a line that passes through the points given in the table? Check all that apply. y 2 = 6(x + 10) y 2 = (x + 10) y 1 = (x + 4) y = 6x 58 y = x + y = x + 5 3 x : 10 = 5 : 2 Calculate the value of x find the area of the figure below. round your answer to the nearest tenth 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 Cainas Cookies purchased a commercial oven on 1/1/14 for a total cost of 35,000. Estimated useful life is 6 years, with a salvage value of 5,000 at the end of that time. Cainas estimates that the equipment will be used for 12,000 baking hours. For the first year of operations, Cainas had 2,500 backing hours. For the second year Cainas had 1,700 hours. Compute the depreciation for YEAR 2. Group of answer choices Air flows along a horizontal, curved streamline with a 20 foot radius with a speed of 100 ft/s. Determine the pressure gradient normal to the streamline. Given the following selected information on McMillen's Chocolate, Inc., calculate Cash Flow from Operating Activities for 2012. Show your work.2011 2012EAT $ 600,000 800,000Depreciation Exp. 100,000 120,000Dividends 400,000 550,000Accounts Receivable 1,500,000 1,000,000Inventory 3,500,000 4,100,000Accts. Payable 350,000 350,000Accruals 250,000 200,000Long-Term Debt 2,300,000 2,000,000Common Stock 2,200,000 3,000,000Interest expenses 50,000 60,000Retained Earnings 6,150,000 6,400,000 Circle F is congruent to circle J, and EFD GJH. Circles F and J are congruent. Line segments F E and F D are radii. A line connects points E and D to form a triangle. Line segments J H and J G are radii. A line connects points H and G to form a triangle. Angles D F E and G J H are congruent. mDFE = 80. What is the measure of arc Arc G H? 1 2.1.5 Quiz: Specialized Cells and TissuesQuestion 5 of 52 PointsWhich statement best explains how the needs of a unicellular organism aremet?A. Only its specialized cells work together.B. All of its cells must work together.C. Most of its tissues work together.D. Its cell parts must do everything.SUBMIT Modifiable strength improvement factors include all of the following except...?? There are 4562 boys in a school. The number of girls is 689 less than the number ofboys. Find the total strength of the school. Pls answer fast A cowboy fires a silver bullet with a muzzle speed of 200 m/s into the pine wall of a saloon. Assume all the internal energy generated by the impact remains with the bullet. What is the temperature change of the bullet? A nurse is reinforcing teaching with a group of healthy older adult clients aboutexpected age-related changes and sexual responses. Which of the following changesshould the nurse include as an age-related change? 5x+2y=57 what is x and y equal to? The question is in the image below.