Answer: The United States
The United States is the only country to have successfully conducted crewed missions to the Moon, with the last departing the lunar surface in December 1972.
Explanation:
Answer
Only the United States has successfully landed men on the moon.
Explanation:
The United States is the only country to have successfully conducted crewed missions to the Moon, with the last departing the lunar surface in December 1972.
Balance the Chemical Equation
Pb(OH)2 + HCl ---> H2O + PbCl2
Please help
Answer:
Pb(OH)2 + 2 HCl ---> 2H2o + PbCl2
Explanation:
2. How many atoms are in 5.6 moles of Na? Answer:___3.2 E 24 atoms of Na
Answer:
5.6[tex]\frac{6.02*10^{23} }{1}[/tex] = 3.4 X [tex]10^{24}[/tex]
Explanation:
the correct answer to it is 3.4 instead of 3.2. I got 3.4 from rounding it from 3.37.
The number of atoms in 5.6 moles of Na have been [tex]\rm \bold{3.37\;\times\;10^2^4}[/tex] atoms.
Atoms have been defined as the smallest unit of matter. The number of atoms in a mole of compound has been given by Avogadro law.
According to the Avogadro law, the number of atoms in mole of sample has been equal to the Avogadro number. The values of Avogadro number has been [tex]6.023\;\times\;10^2^3[/tex].
Computation for the atoms in NaThe available moles of Na have been 5.6 moles.
The number of atoms has been given by:
[tex]\rm 1\;mol=6.023\;\times\;10^2^3\;atoms\\ 5.6\;mol=5.6\;\times\;6.023\;\times\;10^2^3\;atoms\\ 5.6\;mol=3.37\;\times\;10^2^4\;atoms[/tex]
The number of atoms in 5.6 moles of Na have been [tex]\rm \bold{3.37\;\times\;10^2^4}[/tex] atoms.
Learn more about number of atoms, here:
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when an electron gets closer to the nucleus does the attraction or repulsion grow weaker or stronger?
Answer:
Weaker
Explanation:
Since the charges on nucleus and electron are opposite in nature, an attractive force exists between them. It is true in generally, that when objects are made to move closer together in the direction of an attractive force, potential energy decreases (and increases whenever attracting objects are force to move apart).
Here, we are required to determine if the attraction or repulsion grow weaker or stronger.
When electrons get closer to the nucleus, the attraction grows stronger.First, we must establish scenarios when there can be attraction and ones where there can be repulsion.
By the law guiding electric charges; In electrical interactions:
Like poles repel while Unlike poles attract.
Also, in the atomic model; the nucleus is positively charged as it contains protons (+vely charged) and neutrons which are uncharged particles.Since the nucleus is positively charged and the electrons revolve round their orbit. Therefore, the force is an attraction force.As we all know that the force of attraction or of repulsion as the case may be is inversely proportional to the distance between the charged particles (the electrons and the nucleus in this case)When an electron gets closer to the nucleus, the distance between the electron and the nucleus reduces; and the force of attraction between the electron and the nucleus increases.Ultimately, when an electron gets closer to the nucleus, the attraction force will grow stronger due to the reduced distance between the electron and the nucleus.
Read more:
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why water is not used as a thermometric substance
Answer:
Water can be used as the thermometric liquid. It expands and contracts with temperature so it can be used. It's just not a very good choice because: It's thermal expansion is not very large compared to other liquids like mercury.
Explanation:
Hope this help
How do you draw a lewis structure?
Answer:
How to Draw a Lewis Structure.
Step 1: Find the Total Number of Valence Electrons.
Step 2: Find the Number of Electrons Needed to Make the Atoms "Happy".
Step 3: Determine the Number of Bonds in the Molecule.
Step 4: Choose a Central Atom.
Step 5: Draw a Skeletal Structure.
Step 6: Place Electrons Around Outside Atoms.
Explanation:
Hope this helped! :)
Star A and star B are the same distance away from earth. From earth, star A seems brighter than star B. Which star has the highest absolute brightness?
Answer:
Star B
Explanation:
Star B, this is because, usually in the discussions about stars, the more luminous star or say, the brighter star usually is the one that possesses the smaller absolute brightness.
That being said, succinctly put, if we have two stars A and star B, if star A is brighter than star B, then star A has a lower absolute brightness. Also, if star B is less brighter than star A, then it has the higher absolute brightness.
Answer:
STAR B
Explanation:
Which section of the ocean floor is near the coastline of all continents
Give 3 examples of conduction, radiation, and convection.
Answer:Conduction: Touching a stove and being burned. Ice cooling down your hand
Convection: Hot air rising, cooling, and falling (convection currents)
Radiation: Heat from the sun warming your face
Explanation:
Answer:
Radiation: Radio Waves, Conduction: An ice cube on a warm hand, Convection: A radiator
Someone please tell me what the epithelial tissue does. This question gives you 20 points btw if you answer
Answer:
They form the covering of all body surfaces, line body cavities and hollow organs, and are the major tissue in glands. They perform a variety of functions that include protection, secretion, absorption, excretion, filtration, diffusion, and sensory reception
Explanation:
They form the covering of all body surfaces, line body cavities and hollow organs, and are the major tissue in glands. They perform a variety of functions that include protection, secretion, absorption, excretion, filtration, diffusion, and sensory reception
label each as a physical or chemical change & explain your reasoning.
Answer:
1st chemical equation → Chemical change
2nd chemical equation → Physical change
3rd chemical equation → Physical change
4th chemical equation → Chemical change
Explanation:
Chemical change has to the do with the creation of an entirely new product or substance. When two reactants react and form entirely new product(s), we say that a chemical change has occurred.
While a physical change does not create an entirely new substance or product; it can only change to a new form or state.
From the given equations, we discover that in the first equation, propane reacted with oxygen to give carbon (II) oxide and water (entirely new products) while in the second chemical equation, ethanol is a liquid (at room temperature) but later changes its state to gas (physical change).
The above answer is correct.
Determine the empirical formula for a compound with 68.4% Cr and 31.6% O. Show your work in the space below.
Answer:
Cr2O3
Explanation:
To find the empirical formula, which is the smallest whole number ratio of a compound, the following is done:
68.4% Cr = 68.4g of Chromium
31.6% O = 31.6g of Oxygen
Since, Cr = 52, O = 16, divide each mass by their respective atomic mass to convert to moles.
Cr = 68.4/52 = 1.315 mol
O = 31.6/16 = 1.975 mol
- Next, we divide each mole value by the smallest value (1.315mol)
Cr = 1.315/1.315 = 1
O = 1.975/1.315 = 1.50
The ratio or Cr to O is 1:1.5
We multiply this ratio by 2 to get the whole number ratio as follows:
2 × 1: 2 × 1.5
2:3
Hence, the empirical formula of Cr and oxygen is Cr2O3.
- How many grams are in 4.6 x 1016 molecules of phosphorus trichloride (PCI)?
Answer:
0.0000101 grams.
Explanation:
First of all, use Avogadro's number to convert from molecules to moles.
Avogadro's number is 6.02 x 10^23.
Second of all, to convert from moles to grams, find the substance formula of phosphorus trichloride. After finding the substance formula, then find the molar mass of phosphorus trichloride.
Phosphorus trichloride is PCl3
Now find the molar mass of PCl3
P = 31.0 amu
Cl = 35.5 amu
They are three chlorine atoms and one phosphorus atom. So you do this.
31.0(1) + 35.5(3) = 137.5 g/mol
Now use dimensional analysis to show your work
4.6 x 10^16 grams of PCl3 * 1 mol/ 6.02 x 10^23 * 137.5 g/mol / 1 mol
The grams and the moles cancel out.
So now do [(4.6 x 10^16) / (6.02 x 10^23)] x 137.5
and you will get 0.000010507
4.6 has the fewest digits which is 2.
So use sig figs and the answer rounds to the nearest millionths.
0.000010507 rounds to 0.0000101
So the final answer is 0.0000101 grams(don't forget the units)
Hope it helped!
Is Ni(NO3)3 ionic or covalent and why
The Ni ( NO₃ )₃ is an anhydrous covalent compound. Ni ( NO₃ )₃ is prepared by the reaction of red fuming nitric acid and nickel nitrate hemihydrate.
What is covalent compound ?An electron exchange that results in the formation of electron pairs between atoms is known as a covalent bond. Bonding pairs or sharing pairs are the names given to these electron pairs. Covalent bonding is the stable equilibrium of the attractive and repulsive forces between atoms when they share electrons.
At room temperature, covalent compounds can be found in all three of their physical states and often have low boiling and melting temperatures. Because covalent compounds lack charged particles with the ability to carry electrons, they do not conduct electricity.
Two atoms sharing a pair of electrons make a covalent connection. Because the electron pair is drawn to both nuclei, the atoms are kept together.
Thus, The Ni ( NO₃ )₃ is an anhydrous covalent compound.
To learn more about covalent compound, follow the link;
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A sample of He has volume of 4.40 L at 555 torr and 33.0 C. Find the new pressure if the volume decreases to 3.50 L and the temperature increases to 44.0 C.
723 torr
504 torr
800. torr
612 torr
Answer:
723 torr
Explanation:
Using the formula;
P1V1/T1 = P2V2/T2
Where;
P1 = initial pressure (torr)
V1 = initial volume (Litres)
T1 = initial temperature (°C)
P2 = final pressure (torr)
V2 = final volume (L)
T2 = final temperature (°C)
Based on the information provided in this question, V1 = 4.40L, P1 = 555 torr, T1 = 33.0 °C + 273 = 306K, V2 = 3.50 L, P2 = ?, T2 = 44.0 °C + 273 = 317K.
Using the formula above:
555 × 4.4/306 = P2 × 3.5/317
2442/306 = 3.5P2/317
Cross multiply;
2442 × 317 = 306 × 3.5P2
774114 = 1071 P2
P2 = 774114 ÷ 1071
P2 = 722.79
P2 = 723 Torr
What is the number of protons for 2^1H?
A solution is oversaturated,Which could be done to decrease the oversaturation?
dilute the solution
add more solute
cool the solution
add a different solute
A solution is oversaturated,Which could be done to decrease the oversaturation?
dilute the solution
add more solute
cool the solution
add a different solute
Answer:
AAAAAAAAAAAAA i just finished the exam
Explanation:
The reactants of two reactions are shown,
Reaction 1: C and O2
Reaction 2: K2SO4, and CaCl,
Which reaction is likely to be a redox reaction? (1 point)
Only Reaction 2, because potassium and calcium ions will interchange their positions
Both, because the electrostatic charge on cations will change during each reaction
Both, because the electrostatic charge on anions will change during each reaction
Only Reaction 1, because the charge of carbon changes during the reaction
Answer:
Only reaction 1
Explanation:
C + O2 → CO
the charge of C in CO is +2 (oxidation)
from 0 to +2
the charge of O in CO is -2 (reduction)
from 0 fo -2
Hence it is a redox (reduction-oxidation) reaction
This is also valid for,
C + O2 → CO2
the charge of C in CO2 is +4 (oxidation)
charge increases from 0 to +4
the charge of O in CO2 is -2 (reduction)
charge decreases from 0 to -2
hence, it is a redox reaction
K2SO4 + CaCl → KCl + CaSO4
none of the charges changes in this reaction
please recheck, for this may not be the correct answer
. The kidneys are _______________ to the liver.
a. Dorsal
b. Ventral
c. Medial
d. Superior
2. Convert 5.3 x 1025 molecules of CO2 to moles.
ANSWER:
moles CO2 = 88 mol
EXPLAIN:
In order to go from molecules of CO2 to moles of CO2, we have to use the following relationship:
I usually set up dimensional analysis questions like this:
Quantity sought = Quantity given x conversion factor
Quantity sought → mol CO2Quantity given → 5.3×1025 moleculesConversion factor → 1mol/6.02×10∧23Now we just plug the values into the format I have above (make sure your units cancel out as you are going through this process, that's how you know if you are doing the calculations correctly or not):
moles CO2 = 5.3×10∧25 molecules×1mol/6.02×10∧23 molecules
moles CO2 = 88 mol
Which elements are found only along a zigzag line that divides columns 13 through 18 on the periodic table?
A. Metalloids
B. Metals
C. Nonmetals
D. Representative metals
Answer:
A. Metalloids.
Explanation:
Metalloids. Metalloids, also called semiconductors, are the elements that border the zigzag line on the periodic table.
A sample of carbon dioxide gas at a pressure of 891 mm Hg and a temperature of 84 C occupies a volume of 5.61 L. If the gas is cooled at constant pressure to a temperature of 40 C, the volume of the gas will be __ L.
Answer:
4.92L
Explanation:
Given parameters:
Initial pressure = 891mmHg
Initial temperature = 84°C = 84 + 273 = 357k
Initial volume = 5.61L
New temperature = 40°C = 273 + 40 = 313k
Unknown:
New volume = ?
Solution:
Since we are dealing with constant pressure condition, we apply charles's law.
It states that the volume of a fixed mass of gas varies directly as its absolute temperature if the pressure is constant.
Mathematically ;
[tex]\frac{V1}{T1}[/tex] = [tex]\frac{V2}{T2}[/tex]
V1 is the initial volume V2 is the new volume
T1 is the initial temperature T2 is the new temperature
[tex]\frac{5.61}{357}[/tex] = [tex]\frac{V2}{313}[/tex]
V2 = 4.92L
If we react 5.4g of sodium chloride with an unknown amount of fluorine gas, we produce 4.9g of sodium fluoride and 3.7g chlorine gas. How much fluorine was consumed in the reaction?
Answer:
1.9g of F₂ were consumed in the reaction
Explanation:
Based on the chemical reaction:
2NaCl + F₂ → 2 NaF + Cl₂
Where 2 moles of NaCl react per mole of F₂ to produce 2 moles of NaF and 1 mole of Cl₂
To understand in a better way how the reaction occurs we need to convert each mass of compound to moles:
Moles of NaCl -Molar mass: 58.44g/mol-:
5.4g * (1mol / 58.44g) = 0.092 moles NaCl
Moles of NaF -Molar mass: 41.988g/mol-:
4.9g * (1mol / 41.998g) = 0.12 moles NaF
Moles of Cl₂ -Molar mass: 70.90g/mol-:
3.7g * (1mol / 70.90g) = 0.052 moles Cl₂
That means approximately 0.1 moles of NaCl react with 0.05 moles of F₂ to produce 0.1moles of NaF and 0.05 moles of Cl₂.
0.05 moles of F₂ are:
0.05 moles * (38g/mol) =
1.9g of F₂ were consumed in the reactionYou have a particle of length 68 nm. What is this in meters? ( need help asap)
Answer:
B
Explanation:
In some areas of Texas, rainfall quickly soaks through layers of porous rock and is stored naturally underground. The water is then pumped into homes for people to use. What would have the greatest impact on the amount of water available for people in this area?
Explanation:
The amount of rainfall would have the greatest impact on the amount of water available for people in this area. The more the rainfall the more water soaks through layers of porous rocks.Hence, level of water table will remain sufficient for easy pumping of water to the homes.Texas receives plenty of rainfall in a year.In a single year the region can receive up to 48 inches (1,200 mm) of precipitation, and flooding is common near rivers and in low-lying areas. Therefore water table remains intact throughout the year.
Bohr's model of the atom attempts to explain the idea that
the atom is mostly empty space
O all atoms of one type of element are identical
O energy is quantized
O protons and neutrons are found in the nucleus
Answer:
O energy is quantized
Explanation:
Bohr's model of that atom attempts to explain the idea that energy is quantized within an atomic space.
In 1913 Neils Bohr put forward his own model of the atom based on the quantum mechanics developed by Planck. He suggested that the extranuclear part consists of electrons in specific spherical orbits around the nucleus. As one moves outwards from the nucleus the energy level increases.Give the name of one of the 3 common acids used in chemistry
Answer:
Common strong acids include hydrochloric acid, sulfuric acid, phosphoric acid, and nitric acid. Common weak acids include acetic acid, boric acid, hydrofluoric acid, oxalic acid, citric acid, and carbonic acid.
Observe the image of sodium. List the properties you see.
Answer:
It is soft and white. It has a low melting and boiling point, a good conductor electricity, and reacts with water. Furthermore, it is also highly reactive, malleable, and ductile.
Explanation:
Hope I helped!
Answer:
silvery-white and waxy
Explanation:
Properties means the observations you can make just by looking at it or the qualities that the object has.
So when I looked at the sodium I saw a silvery-white metal (sodium is a metal), that has this waxy appearance to it.
Use the following equation to answer question 1-4. Make sure you balance first.
6HCI + Fe2O3 --> 2FeCl3 +3H2O
1. How many moles of water are produced from 10.4 moles of hydrochloric acid?
5.2 mol H₂O
General Formulas and Concepts:Math
Pre-Algebra
Order of Operations: BPEMDAS
Brackets Parenthesis Exponents Multiplication Division Addition Subtraction Left to RightChemistry
Stoichiometry
Using Dimensional AnalysisExplanation:Step 1: Define
[RxN - Balanced] 6HCl + Fe₂O₃ → 2FeCl₃ + 3H₂O
[Given] 10.4 mol HCl
Step 2: Identify Conversions
[RxN] 6 mol HCl = 3 mol H₂O
Step 3: Stoichiometry
Set up: [tex]\displaystyle 10.4 \ mol \ HCl(\frac{3 \ mol \ H_2O}{6 \ mol \ HCl})[/tex]Multiply/Divide: [tex]\displaystyle 5.2 \ mol \ H_2O[/tex]HEEEEELP PLZ
Which conclusion is most logical, based on the data?
Answer:
its the last one
Answer:
D
Explanation:
A 1.00 L flask is filled with 1.20 g of argon at 25 ∘C. A sample of ethane vapor is added to the same flask until the total pressure is 1.300 atm .
What is the partial pressure of argon, PAr, in the flask?
Answer:
Partial pressure of Ar = 0.73 atm
Explanation:
Given data:
Volume of flask = 1.00 L
Mass of Ar = 1.20 g
Temperature = 25 °C (25+273.15 K= 298.15 k)
Total pressure = 1.300 atm
Partial pressure of Ar = ?
Solution:
First of all we will calculate the number of moles of Ar:
Number of moles = mass/ molar mass
Number of moles = 1.20 g/ 39.95 g/mol
Number of moles = 0.03 mol
Pressure of Ar:
PV = nRT
R = general gas constant = 0.0821 atm.L /mol.K
P×1.00 L = 0.03 mol × 0.0821 atm.L /mol.K× 298.15 k
P = 0.73 atm.L /1.00 L
P = 0.73 atm
Total pressure = Partial Pressure of Ar + Partial pressure of ethane
1.300 atm = 0.73 atm + P(ethane)
P(ethane) = 1.300 atm - 0.73 atm
P(ethane) = 0.57 atm