Which of the following options correctly describe physical and chemical properties? A- A phase change always occurs when a physical property is measured B- When a chemical property is measured, the substance being observed is converted to a different substance or interacts with another substance. C- A chemical property of a substance can be observed without changing its composition or interacting with another substance. D- A physical property can be observed without a chemical reaction.

Answer:

B) The molecular orbital formed is lower in energy than a hydrogen 1s atomic orbital.

Explanation:

When two atoms of hydrogen come close to each other , there is formation of molecular orbital . Due to overlap of 1 s orbital of one and 1 s orbital of another atom , two molecular orbitals are formed . One of these molecular orbital has energy less than 1 s atomic orbital . It is called 1 s sigma bonding molecular orbital . The other molecular orbital has energy more than 1 s atomic orbital . It is called antibonding molecular orbital . Two electrons occupy bonding sigma molecular orbital .

So , the statement that "the molecular orbital formed is lower in energy than a hydrogen 1s atomic orbital " is wrong .

Answer:

A. The solution with a pH of 2 will turn the litmus paper red

B. The solution with a pH of 8 will turn the China rose indicator green

C. The solution with a Ph of 7 will not change the color of the blue litmus indicator or of the China rose indicator

Explanation:

Blue litmus paper will only change color if it is dipped into an acidic mixture which turns it red. It will not change color at all in a basic or neutral Ph solution.

China rose turns dark pink in an acidic solution and green in a basic solution. However it has no change in color with a neutral solution.

Answer:

the density increases

Explanation:

Coz high temperature makes water less dense. As water gets warmer, its molecules spread out, so it becomes less dense. As it gets colder, it becomes denser

Answer:

the rest mass of an electron is 9.1093837915

Answer:

Fundamental properties. The invariant mass of an electron is approximately 9.109×10−31 kilograms, or 5.489×10−4 atomic mass units. On the basis of Einstein's principle of mass–energy equivalence, this mass corresponds to a rest energy of 0.511

Answer:

See explanation

Explanation:

In this question, we have to remember that in all combustion reactions we will have Oxygen as reactive ([tex]O_2[/tex]) and the products are Carbon dioxide ([tex]CO_2[/tex]) and Water ([tex]H_2O[/tex]). Additionally, for the states, we will have (l) for the liquid state and (g) for the gas state. So, we can analyze each reaction:

Part A.

The formula for nonane is [tex]C_9H_2_0[/tex], with this in mind we can write the combustion reaction:

[tex]C_9H_2_0_(_I_)~ +~ O_2~->~CO_2_(_g_)~ +~H_2O_(_g_) [/tex]

When we balance the reaction we will obtain:

[tex]C_9H_2_0_(_I_)~ +~14 O_2_(_g_)~->~9CO_2_(_g_)~ +~10H_2O_(_g_) [/tex]

Part B.

The formula for 2-methylbutane is [tex]C_5H_1_2[/tex], with this in mind we can write the combustion reaction:

[tex]C5H12_(_I_)~ +~O_2_(_g_)~->~CO_2_(_g_)~ +~H2O_(_g_) [/tex]

When we balance the reaction we will obtain:

[tex]C5H12_(_I_)~ +~8O_2_(_g_)~->~5 CO_2_(_g_)~ +~6 H2O_(_g_) [/tex]

Part C.

The formula for 3-ethyltoluene is [tex]C_9H_1_2[/tex], with this in mind we can write the combustion reaction:

[tex]C_9H_1_2_(_I_)~+~O_2_(_g_)~->~CO_2_(_g_)~+~H2O_(_g_)[/tex]

When we balance the reaction we will obtain:

[tex]C9H12_(_I_)~ +~12O_2_(_g_)~->~9CO_2_(_g_)~ +~6H2O_(_g_)[/tex]

See figure 1 for further explanations.

I hope it helps!

Answer:

74ifhdyteuyteutyruf

Answer:

Presence of impurities in the product.

Explanation:

Laboratory experience has shown that the percent yield obtained from a reaction may be greater than 100% if the product obtained from the reaction contains impurities that causes its mass to be greater than it actually would be if the product was pure.

A typical impurity that may be present in a product is the solvent used. This can be removed by evaporation of the solvent or by washing the product thoroughly.

Reaction of solid products with gases may also increase the percentage yield above 100%.

Explanation:

Hey there!!

The answer is Electrons.

Electrons are the small part of an atom that revolves around the nucleus of an atom.

Hope it helps..

Answer:

4320 inches

Explanation:

math

A football field is supposed to be exactly 120yd long, including the end zones is 4320 inches.

Zones are defined as a space that is physically or artificially isolated from other spaces. There are numerous sorts and sizes of zones.

Zones are also defined as a region that is designated as having a specific average annual minimum temperature, which is important for many plants to survive.

There are four types of zones.

The Torrid Zone, Temperate Zone, and Frigid Zone are the three temperature-based regions of the Earth.

Planting zones are predetermined areas based on the types of plants that thrive there.

Thus, a football field is supposed to be exactly 120yd long, including the end zones is 4320 inches.

To learn more about zones, refer to the link below:

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#SPJ12

Answer:

1. d. Person A rounded their measurement

2) a. 105.

b. 76.4

c. 0.04

d. 1.988

Explanation:

1. Measuring an object is done with the least precise one. Person A recorded 1.5cm while Person B recorded 1.50cm of the same object. This measurement differs in the sense that Person A rounded up their measurement to 2 significant figures (1.5) while Person B recorded their answer as three significant figures (1.50).

2. During multiplication and division, the result is written as the measurement in the lowest significant figure.

a. 7.00 x 15.00 = 105. Calculator showed 105.00, which is 5 s.f (two zeros after decimal point are significant). The least significant figure is 3, hence 105.00 is rounded up to 105.

b. 40.2.1.901 = 76.4; The calculator answer of this operation is 76.420200 but since the lowest significant figure is 3. We round up our answer to 3 s.f i.e. 76.4

c. (0.003)(13.2) = 0.04. For this operation, calculator answer is 0.0396, however, the lowest significant figure in the question is 1 i.e. 0.003. Note that the two zeros before 3 are insignificant. Hence, our answer will be rounded up to 1 s.f i.e. 0.04

d. 1.590+ 0.3975 = 1.988. the calculator answer to this operation is 1.9875. However, the least significant figure in the question is 4 i.e. 1.590. hence, the answer will be rounded up to 4 s.f which is 1.988.

Answer:

Calculate the unknown variable in the equation for gravitational potential energy, where potential energy is equal to mass multiplied by gravity and height; PE = mgh. Calculate for different gravity of different enviornments - Earth, the Moon, Jupiter, or specify your own. Free online physics calculators, mechanics, energy, calculators.

Explanation:

Answer: 65%

Explanation:

When in probability and the outcome is mutually exclusive which means that either one or the other will happen then the probabilities of the events should be added up.

P(A or B) = P(A) + P(B)

P(Rain or Hail) = P(Rain) + P(Hail)

P(Rain or Hail) = 30% + 35%

P(Rain or Hail) = 65%

Answer:

ΔH = 87.8kJ

Explanation:

You can determine ΔH of a reaction from the sum of similar reactions (Hess's law). In the problem with the given ΔH:

1. C5H12(l)+8O2(g)→ 5CO2(g)+6H2O(g) ΔH= -3505.8 kJ

2. C(s)+O2(g)→CO2(g) ΔH= -393.5 kJ

3. 2H2(g)+O2(g)→ 2H2O(g) ΔH= -483.5 kJ

5 times 2. + 3 times 3:

5C(s) + 8O2(g) + 6H2(g) → 5CO2(g) + 6H2O(g)  

ΔH= 5*(-393.5 kJ) +  3*(-483.5 kJ) = -3418kJ

Now, this reaction - 1:

5C(s)+6H2(g) → C5H12(l) ΔH= -3418kJ - (-3505.8kJ)

Answer:

B. what happens when iron rusts in the presence of water

Explanation:

Answer:

28.705 cm

Explanation:

Hello,

In this case, for rounding the number to five significant figures we must "cut" it at 5 so we hide the 3, therefore it turns out:

28.705 cm.

Moreover, we must realize that since such 3 is less than five, we do not modify the previous five to six, case which would happen if that three has changed to five or more.

Regards.

Answer:

The  correct option is  D

Explanation:

From the question we are told that

 The pH of the aqueous solution is  [tex]pH  =  7[/tex]

 The  isoelectric point  is  [tex]pl =  9[/tex]

From the data given we see that the  

        [tex]pH[/tex] is  below  [tex]pl[/tex]

So the protein will have a net positive charge

A protein has an isoelectric point (pI) of 9, the statement which best describes the state of this protein is that the protein will have a net positive charge.

Isoelectric point of any susbatnce is the pH of the substance where net charge on that substance will be zero, i.e. no. of positive charged ions will equal to the number of negative charged ions.

In the question it is given that value of isoelectric point (pl) of protein is 9 and given value of pH is 7. It means that isoelectric point is higher that given pH so the protein molecule should bear a positive charge on it. If pH value is greater than pl value then molecule will bear a negative charge.

Hence option (D) is correct.

To know more about isoelectric point, visit the below link:
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A variable within a scientific experiment is something that is changed (i.e. it varies). There should be only one manipulated variable within a scientific experiment so that the experimenter can be certain it is this variable which causes a pattern in the resultant data, if any exists at all.

HOPE IT HELPS PLZ BRAINLIEST

Answer:

For 1 hour 75w light bulb requires 270 kj  for burning

for 3 hours 75 w light bulb requires 270*3 = 810kj for burning

Explanation:

Answer:

Protons: 26

Neutrons: 30

Explanation:

Answer:

Surface tension

Capillary action

Explanation:

Surface tension is the force acting along the surface of the liquid causing the liquid surface to behave like a stretched elastic skin. Surface tension causes the water drops that fall on a smooth surface to form rounded drops or beads.

If you touch a piece of paper to the drop, water appears to move up into the paper on its own due to capillarity. Capillarity is the tendency of a liquid to rise or fall in a narrow tube.

Answer:

Data obtained can't be accurate.

Explanation:

A beaker can't be used for measuring the volume of a liquid because they did not calculate volume of a liquid accurately and precisely. The marks present on the beaker are not accurate, it is just an estimate so by measuring the volume of any liquid using beaker give us a false data so that's why beaker are not used for the measurement of a volume.

Answer:

No no no and no no no no no no

Answer:

This is quite a controversial question ahaha. Personally, I think pineapple on pizza is good sometimes. depends on the day though.

Explanation:

To me it is a good combination of sweet and salty. The pineapple is also pretty refreshing.

Answer:

Explanation:

Homogeneous mixture is a mixture in which the components of the mixture are in the same proportion throughout any sample extracted from the mixture while an heterogeneous mixture is a mixture in which the components of the mixture differ in term of proportion when different samples of the mixture are extracted and compared.

For example, a sandy water will have some parts (usually the bottom) of the mixture with more sand than other parts of the mixture, hence, it (sandy water) is a heterogeneous mixture. While salty and ocean water has it's salt dissolved in the same proportion throughout the water in the mixture, hence salty and/or ocean water is a homogeneous mixture.

Sandy water can be separated by filtration (i.e using a filter paper to separate the sand from the water when the mixture is poured over a filter paper) while salty and ocean water can be separated by distillation (i.e boiling of the mixture so the water molecules can boil and move through a tube as gas or steam into another container where they are cooled and converted back to liquid or water while leaving the solid salt component of the mixture in the boiling tube).

Answer:

1. because what if you do a incorrect ion? it would be all wrong! 2. you dont get it quickly because! you might get the wrong equipment. 4. yep! no food or drinks!

Explanation:

hope this helps ☻︎

Answer: Sí

Explanation: ya que una mascota es inofensiva, pero para fotografiar a un animal salvaje, debes esperar pacientemente el momento perfecto

Answer:

The mass of  Mg  and the mass of  Cl  in the sample

Explanation:

We have that the sample's is purity is simply the mass of Mg and the mass of Cl in the sample

From the Question we are told that

Mass of MgCl2 =5g

Therefore

What we need to  determine that the sample's is purity is simply the mass of Mg and the mass of Cl in the sample because

the mass of MgCl should be equal to mass of Mg and mas of Cl

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