Answer:
C
Explanation:
The element gold has a consistent melting point and color regardless of the physical changes. This identifies gold as a pure substance. The correct option is C.
What are pure substances?Pure substances are those that are made up of only one type of atom, and nothing is mixed in these substances. They are only one type of particle. They have fixed mass and structure.
Gold is an element that has an atomic number of 79. It is a bright yellow colored and shiny metal. It is used to make an ornament, which is made by mixing other metal to it.
Elements and compounds are subclasses of pure substances. A material that solely contains one type or class of atom is said to be an element. Gold is a pure substance, it is made by one type of atom which is Aurum (Au).
Thus, the correct potion is C. A pure substance.
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A steel cylinder contains 5.00 mol of graphite (pure carbon) and 5.00 mol of O2. The mixture is ignited and all the graphite reacts. Combustion produced a mixture of CO gas and CO2 gas. After the cylinder has cooled to its original temperature, it is found that the pressure in the cylinder has increased by 16.4%. Calculate the mole fractions of CO, CO2, and O2 in the final
Answer:
O₂ = 0.141
CO = 0.282
CO₂ = 0.577
Explanation:
The reaction of graphite with Oxygen is:
C(s) + O₂(g) → CO₂(g) + CO
All 5 moles of C(s) reacts producing CO₂ and CO. You can write:
5 moles = CO₂ + CO (1)
And, as pressure increased by 16.4% and initial moles of oxygen are 5.00 moles. Final moles (Moles of three gases) are:
5.00moles + 5.00moles*16.4% =
5.82 moles = O₂ + CO₂ + CO (2)
Also, there are 10 moles of oxygen in the container, that is:
10 moles = O₂*2 + CO₂*2 + CO (3)
From (2) and (1), moles of O₂ are:
O₂ = 0.82 moles
Replacing in (3)
10 mol = 0.82*2 + CO₂/2 + CO
8.36 moles = CO₂*2 + CO
5 moles = CO₂ + CO
By the sum of these equations:
3.36 moles = CO₂
And
5.0 moles - 3.36 moles = CO
1.64 moles = CO
As total moles are 5.84 moles, mole fraction of the gases is:
O₂ = 0.82 moles / 5.82mol = 0.141CO = 1.64 moles / 5.82mol = 0.282CO₂ = 3.36 moles / 5.82mol = 0.577Q2. The table gives the composition of three particles.
number of
number
of
number of
electrons
particle
neutrons
protons
A
15
15
16
B
15
18
16
A
с
15
15
17
(a) What is the evidence in the table for each of the following?
Particle A is an atom.
[1]
R.A.
Answer:
The proton and electrons are equal,
15protons and 15electrons
Explanation:
An atom is the smallest electrical neutral particle of an element so it means that every atom have same number of protons and electrons.
Marcos and Helen study the electron configurations of neutral atoms. They draw the
atomic models shown. Due to their electron structure, what do the two atoms have in
common?
a. period
b. No answer text provided.
c. group
d. mass number
e. atomic number
To see the number of atoms of an element in a given molecule we need to multiply stoichiometry to the number that is written on the foot of the element that is stoichiometry. The correct option is option C.
What is atom?Atom is the smallest particle of any element, molecule or compound. Atom can not be further divided. Atoms contains nucleus in its center and electron that revolve around the atom in fixed orbit.
In the nucleus, proton and neutron are present. Electron has -1 charge while proton has +1 charge. Neutron is neutral that is it has no charge. So overall the charge of nucleus is due to only proton, not by neutron.
In the two figure the number of electrons in the outermost shell or valence shell is 2. The group of periodic table that has valency 2, is the alkaline earth metals. So, the group number, the two atoms have in common.
Therefore, the correct option is option C.
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If society took the threat of global warming seriously, what kinds of changes would you expect to see in how that society works?
Answer:
Global warming occurs a result of human activities which affects the environment negatively . It usually occurs over a long period of time. The global warming causes climate changes as a result of the ozone layer depletion.
If society took the threat of global warming seriously there will be changes in how humans handle the environment and the resources. Carbon emissions would be greatly reduced. Forest resources such as trees would also be treated specially and there would have been a reduction in mass deforestation as a result of urbanization
ITS TALKING ABOUT PHOTOSYNTHESIS
Xylem helps plants deliver water and nutrients to the
entire plant. What human body system is this like?
The the two important transport tissues in plants are xylem and phloem. The human body system which is like xylem is circulatory system.
What is xylem?An important transport tissue which is found in the vascular plants along with the phloem is defined as the xylem. The major role of xylem is to transport all the essential nutrients and water to leaves and stems from the roots.
There are mainly two types of xylem, they are primary and secondary. The xylem which is found during the primary growth of the plant is called the primary xylem and the secondary xylem is found in the plant's secondary growth.
The xylem transport the substances through passive transport which does not need any external energy. The vessel elements present in the xylem are found to be similar to the blood vessels in the human body.
The blood vessels of the circulatory system carries nutrients to all the organs and removes wastes from the organs. The arteries carry blood away from the heart and veins carry blood to the heart.
Thus the blood vessels in the circulatory system is analogous to the Xylem.
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Atom A has five protons, four neutrons, and five electrons. Atom
B has five protons, six neutrons, and five electrons.
Are atoms A and B isotopes of the same element? Explain how
you know.
SELECT AN ANSWER
They are of the same element because
they have a different number of neutrons.
They are of the same element because
they have the same number of protons and
electrons, but a different number of
neutrons.
They are of the same element because
they have the same number of protons and
neutrons, but a different number of
electrons.
They are of the same element because
they have the same number of protons.
SUBMIT
Answer:
they are the same element because they have the same number of protons and electrons,but a different number of neutrons
what is flowering plant
a plant that has flowers and fruits
What are the boiling points and freezing points (in oC) of a solution of 50.3 g of I2 in 350 g of chloroform? The kb = 3.63 oC/m, the kf = 4.70 oC/m for CHCl3, and the molar mass of I2 is 253.8 g/mol. The normal boiling point for CHCl3 is 61.2 oC, and the normal freezing point for CHCl3 is -63.5 oC.
Answer:
Boiling point: 63.3°C
Freezing point: -66.2°C.
Explanation:
The boiling point of a solution increases regard to boiling point of the pure solvent. In the same way, freezing point decreases regard to pure solvent. The equations are:
Boiling point increasing:
ΔT = kb*m*i
Freezing point depression:
ΔT = kf*m*i
ΔT are the °C that change boiling or freezing point.
m is molality of the solution (moles / kg)
And i is Van't Hoff factor (1 for I₂ in chloroform)
Molality of 50.3g of I₂ in 350g of chloroform is:
50.3g * (1mol / 253.8g) = 0.198 moles in 350g = 0.350kg:
0.198 moles / 0.350kg = 0.566m
Replacing:
Boiling point:
ΔT = kb*m*i
ΔT = 3.63°C/m*0.566m*1
ΔT = 2.1°C
As boiling point of pure substance is 61.2°C, boiling point of the solution is:
61.2°C + 2.1°C = 63.3°C
Freezing point:
ΔT = kf*m*i
ΔT = 4.70°C/m*0.566m*1
ΔT = 2.7°C
As freezing point is -63.5°C, the freezing point of the solution is:
-63.5°C - 2.7°C = -66.2°C
1. List the three measurements that are helpful when working with a gas.
Answer:
Three measurements that are helpful to know when working with a gas are volume, temperature, and pressure. container.
Hope this helps if its wrong correct me.
what is the scientific name for the chemical formula know as P2Os
Explanation:
I know only P2O5 = Phosphorus pentoxide
there is an ice cream shop 6 blocks north of your hotel. how many minutes will it take to walk there and back
Answer:
48 minutes i think
Explanation:
How many molecules are in 2g of O2?
Answer:
That means that the number of O2 molecules present in 2g of O2 is equal to 0.0625*NA. That's 3.76375*10^22. That is a lot of molecules. And we have not even reached the atomic level
What problem occurs if the firework mixture is not pure (i.e., they are dirty or contaminated)?
Answer:
Fireworks cause broad air contamination in a short measure of time
Explanation:
Fireworks cause broad air contamination in a short measure of time, leaving metal particles, hazardous poisons, destructive synthetic compounds and smoke noticeable all around for quite a long time. A portion of the poisons never completely decay or break down, but instead stick around in the earth, harming all they come into contact with
If the firework mixture is not pure, it is capable of causing risks to health conditions by creating hazardous explosives.
Fireworks originate from the Greek word ''pyrotechnics" which implies fire art. Fireworks is simply a missile that explodes with booms and bursts of vibrantly colorful light in a very controlled fashion.
The chemical components used in the preparation of fireworks are dependent upon the color they produce. These include:
Oxidizing agents such as; barium nitrate (green color), strontium nitrate (red color), etc.fuels such as metal powders, charcoal, etc.If these mixtures are impure, it is certain that these can pose a greater risk related to health conditions by exploding abruptly. These impure gases get mixed with the air and also result in environmental hazards by mixing with the water in lakes, rivers, and streams.
In conclusion, the impurity of firework mixture has a greater effect on human health conditions.
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When an organic molecule loses hydrogen atoms it is said to be:_______.
A) reduced
B) oxidized
C) both oxidized and reduced
D) neither oxidized nor reduced
When a saturated hydrocarbon loss a hydrogen involve an unsaturation it oxidises. Thus, when an organic molecule loses hydrogen atoms it is said to be oxidised.
What is oxidation?Oxidation is the process of loss of electron or loss of hydrogen to change into the higher oxidation state. It can also said that reaction with oxygen is oxidation.
The gain of one or more electrons or hydrogen atoms is called reduction . Reduction make a reactant species in lower oxidation state. The species which is reduced is called reductant and the species which is oxidised is called oxidant.
The group or atom which accepts a hydrogen or electrons from other species and oxidise them is called oxidising agents and the groups which give off their hydrogen or electron to other to reduce them is called reducing agents.
Hence, when an organic molecule loses hydrogen atoms it is said to be oxidised.
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If a metal has a density of 8.9 g/ml, and a volume of 200mls, what is the mass?
Answer:
The answer is 1780 gExplanation:
The mass of a substance when given the density and volume can be found by using the formula
mass = Density × volumeFrom the question
volume of metal = 200 mL
density = 8.9 g/mL
We have
mass = 8.9 × 200
We have the final answer as
1780 gHope this helps you
Express a length of 13.63 m in centimeters.
Answer in units of cm.
Answer:
1363cm
Explanation:
1m=100cm
13.63m= 13.63•100cm
13.63m=1363cm
Strontium consists of four isotopes with masses of 84 (abundance 0.50%), 86 (abundance of
9.9%), 87 (abundance of 7.0%), and 88 (abundance of 82.6%).
Calculate the atomic mass of
strontium.
Answer:
M = 87.71 amu
Explanation:
The masses of 4 isotopes of Strontium with abundance is as follows :
84 (abundance 0.50%), 86 (abundance of 9.9%), 87 (abundance of 7.0%), and 88 (abundance of 82.6%). Let M is the atomic mass of Strontium. So,
[tex]M=0.50\%\ \text{of}\ 84+9.9\%\ \text{of}\ 86+7\%\ \text{of}\ 87+82.6\%\ \text{of}\ 88\\\\M=\dfrac{0.5}{100}\times 84+\dfrac{9.9}{100}\times 86+\dfrac{7}{100}\times 87+\dfrac{82.6}{100}\times 88\\\\M=87.71\ \text{amu}[/tex]
So, the atomic mass of Strontium is 87.71 amu.
For the following electron-transfer reaction:
2Ag^+(aq) + Mn(s) rightarrow 2Ag(s) + Mn^2+(aq)
1. The oxidation half-reaction is:_______
2. The reduction half-reaction is:_______
Answer:
1. The oxidation half-reaction is: Mn(s) ⇄ Mn²⁺(aq) + 2e⁻
2. The reduction half-reaction is: Ag⁺(aq) + 1e⁻ ⇄ Ag(s)
Explanation:
Main reaction: 2Ag⁺(aq) + Mn(s) ⇄ 2Ag(s) + Mn²⁺(aq)
In the oxidation half reaction, the oxidation number increases:
Mn changes from 0, in the ground state to Mn²⁺.
The reduction half reaction occurs where the element decrease the oxidation number, because it is gaining electrons.
Silver changes from Ag⁺ to Ag.
1. The oxidation half-reaction is: Mn(s) ⇄ Mn²⁺(aq) + 2e⁻
2. The reduction half-reaction is: Ag⁺(aq) + 1e⁻ ⇄ Ag(s)
To balance the hole reaction, we need to multiply by 2, the second half reaction:
Mn(s) ⇄ Mn²⁺(aq) + 2e⁻
(Ag⁺(aq) + 1e⁻ ⇄ Ag(s)) . 2
2Ag⁺(aq) + 2e⁻ ⇄ 2Ag(s)
Now we sum, and we can cancel the electrons:
2Ag⁺(aq) + Mn(s) + 2e⁻ ⇄ 2Ag(s) + Mn²⁺(aq) + 2e⁻
What is the heaviest gas element
Answer:
Radon
Explanation:
n 1908 Ramsay and Gray, who named it niton, isolated the element and determined its density, finding it to be the heaviest known gas. It is essentially inert and occupies the last place in the zero group of gases in the Periodic Table. Since 1923, it has been called radon.
Part 1: Cats falling out of windows
Answer:
A cat that falls out of the window even if it seems to be doing well, must urgently go to a veterinary clinic in order to be placed under surveillance for at least 24 to 72 hours
Explanation:
Which of the following is a chemical property of paper? (4A)
Paper will float on water.
Paper absorbs pen ink.
Paper is white.
Paper will burn.
Answer:
D.) Paper will burn
Explanation:
The first three are physical properties of paper, but the last one is a chemical property of paper
How did the US government change its policy toward Native American land during the 1850s?
They began to designate all land on the Great Plains as reservation land
They created new treaties and reservations that defined specific boundaries for each tribe
They began to allow Native Americans to hunt on their traditional lands
The started forbidding settlers from claiming any land on the Great Plains
Reduced grazing lands
• Hunting for sport and
Answer:
The correct answer is B) They created new treaties and reservations that defined specific boundaries for each tribe
Explanation:
One of such acts which was used to reallocate the Native American Land was the General Allotment (Dawes) Act of 1887.
It gave permission to the Federal Government to modify the size and ownership structure of land belonging to the Native Americans. The end result was that the total amount of land originally belonging to the Native Americans reduced drastically over the next 500 years.
Cheers!
Hydrogen gas, H2, reacts explosively with gaseous chlorine, Cl2, to form hydrogen chloride, HCl(g). What is the enthalpy change for the reaction of 2 mole of H2(g) with 2 mole of Cl2(g) if both the reactants and products are at standard state conditions? The standard enthalpy of formation of HCl(g) is −92.3 kJ/mol. H2(g)+Cl2(g)→2HCl(g)
Answer:
-184.6 KJ/mole
Explanation:
H2(g) + Cl2(g) ------------> 2HCl(aq)
Δ H0 rxn = Δ H0f products - Δ H0f reactants
= 2×-92.3 - (0 + 0)
= -184.6KJ/mole
H2(g) + Cl2(g) ------------> 2HCl(aq) Δ H0rxn = -184.6KJ/mole
Given :
Hydrogen gas,[tex]H_2[/tex] , reacts explosively with gaseous chlorine, [tex]Cl_2[/tex], to form hydrogen chloride, HCl(g).
The standard enthalpy of formation of HCl(g) is −92.3 kJ/mol.
[tex]H_2(g)+Cl_2(g) - >2HCl(g)[/tex]
To Find :
The enthalpy change for the reaction of 2 mole of [tex]H_2(g)[/tex] with 2 mole of [tex]Cl_2(g)[/tex] if both the reactants and products are at standard state conditions .
Solution :
We know ,
[tex]\Delta H^o_{rxn}=\Delta H^{o}f_{products}-\Delta H^of_{reactants}\\\\\Delta H^o_{rxn}=2\times (-92.3)-(0+0)\\\\\Delta H^o_{rxn}=-184.6\ kJ/mol[/tex]
( Since , [tex]H_2[/tex] and [tex]Cl_2[/tex] are their most elementary form . So their enthalpy of formation is 0 kJ )
Therefore , the enthalpy change for the reaction of 2 mole of [tex]H_2(g)[/tex] with 2 mole of [tex]Cl_2(g)[/tex] if both the reactants and products are at standard state conditions is -184.6 kJ/mol .
Hence , this is the required solution .
Sort the examples based on whether they describe a physical change or a chemical reaction. growth of a seed into a seedling tarnishing of silver wax melting from applied heat making caramel by burning sugar grinding wheat to make flour adding copper with gold to make jewelry
Answer: I did the research myself since I couldn’t find the answers.
Physical change:
Wax melting from applied heat
Grinding wheat to make flour
Adding copper with gold to make jewelry
Chemical Reaction:
Growth of a seed into a seedling
Making caramel by burning sugar
Tarnishing of silver
Explanation:
Thanks google
Answer:
Physical change:
Wax melting from applied heat
Grinding wheat to make flour
Adding copper with gold to make jewelry
Chemical Reaction:
Growth of a seed into a seedling
Making caramel by burning sugar
Tarnishing of silver
Explanation: I had to take a test.
The table shows the students data from an investigation about a plant growth and five plants of the same type what is the best way to display this data for analyst
Answer:
This question is incomplete
Explanation:
The question is incomplete because of the absence of the table but since the question says there are data from an investigation about a plant growth and five other plants (making six) of the same type, the best way to display this type of data for analyst is to use the grouped bar chart. The grouped bar chart will display the data obtained (from an investigation on plant growth) from different students on each of the six plants (of the the same type).
Colours are usually used to identify the bars (of a group) or could be used to separate the group from other groups but in this case, colours are better used to identify the bars of a group.
carboxylamine reaction
Answer:
Explanation:
The direct reaction of a carboxylic acid with an amine would be expected to be difficult because the basic amine would deprotonate the carboxylic acid to form a highly unreactive carboxylate.
How does the number of valence electrons in atoms of metalloids explain why metalloids are semiconductors?
A.They have one or two valence electrons, so they cannot lose electrons easily.
B.They have one or two valence electrons, so they can lose or gain electrons.
C.They have three to six valence electrons, so they cannot lose electrons easily.
D.They have three to six valence electrons, so they can lose or gain electrons.
sorry its supposed to say physics not chemistry at the top -_-
Answer:
They have three to six valence electrons, so they can lose or gain electrons.
Explanation:
just took the quiz
Metalloids are metal like elements showing intermediate properties of gases and metals. They have three to six valence electrons, so they can lose or gain electrons. That's why they are conducting.
What are metalloids?Metalloids are elements showing properties intermediate to that of metals and non-metals. They are located in the periodic table in between metals and nonmetals.
Metalloids appear as metals. They are shiny and conducting. However, their conductivity is low compared to metals and they are classified as semiconductors and they are all brittle in nature.
Boron, silicon, germanium, arsenic etc. examples of metalloids. They contains three to six valence electrons which can be delocalized or lost from the atoms.
These elements can lose electrons as well they can gain more electrons as per the bonding type. The delocalized valence electrons make them conducting. Hence option D is correct.
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Draw a structural formula for 4,4-dichlorocyclohexanecarboxylic acid.
Answer:
See attached picture.
Explanation:
Hello,
In this case, for the required carboxylic acid, we should consider a central cyclohexane that at the first carbon has a carboxyl group COOH and at the fourth carbon has two chlorine radicals as shown on the attached picture. This type of compounds need to have the carboxyl group outside the ring in order to be considered as acids, otherwise the octet rule may not be respected for a cyclic carbon.
Regards.
How many millimeters of 5 M NaCl are required to prepare 1500 mL of 0.002 M NaCl?
Answer:
The correct answer is 0.6 mL.
Explanation:
We use the mathematical expression:
Ci x Vi = Cf x Vf
Where Ci is the initial concentration (5 M); Cf and Vf refers to final concentration (0.002 M) and final volume (1500 mL). With the given data, we calculate the initial volume (Vi):
Vi = (Cf x Vf)/Ci = (0.002 M x 1500 mL)/(5 M) = 0.6 mL
Therefore, we need 0.6 mL of 5 M NaCl to prepare the solution with the requested dilution.
What does it mean to be "moderated by water"?
water is watching over you
Answer:
it means the higher the water content in the air, the more moderate (less extreme) the climate is.
