Answer:
Postulates of Dalton's Atomic Theory:
1) Atoms can neither be created nor destroyed.
2) During chemical reaction, atoms combine or separate or re-arrange. They combine in simple ratios.
3) All elements are composed of the indivisible particles called atoms.
4) Atoms of a particular element are identical. They have the same mass and volume.
Postulates of modern atomic theory:
1) All matter is composed of atoms.
2) Atoms consist of protons, electrons and neutrons.
3) Atoms of an element may differ in masses. (as in isotopes)
4) The ratio in which elements combine may not be simple.
Similarities:
1) All elements/matter are/is composed of atoms.
2) Atoms can neither be created nor destroyed.
3) During chemical reactions, atom combine or separate or rearrange.
Differences:
1) Dalton's theory said that atoms are indivisible particles but modern theory denies it and calls atom a divisible particle consisting of sub-atomic particles, protons, electrons and neutrons.
2) Dalton's theory said that atoms of the same element have same mass and volume but according to modern theory, it is said that atoms of the same element can differ in mass (as in isotopes).
3) Dalton said that atoms combine in simple ratio but modern theory denies it.
[tex]\rule[225]{225}{2}[/tex]
Hope this helped!
~AH1807Which have different numbers of electrons?
different ions of an element
different isotopes of an element
the nucleus of an element
each of the atoms of an element
Answer: different ions of an element, the answer is A
Explanation: Took the quiz
Answer:
different ions of an element, the answer is A
Explanation:
edge 2022
Please help with chemistry!
Answer:
name is Ian symbol is spices mass number is 100
Explanation:
#
Based on Periodic Law, how is the Periodic Table arranged?
Answer:
Elements of the periodic table are arranged in order of increasing atomic number. the periodic law states "when elements are arranged in increasing atomic number, there is a periodic repetition of their chemical and physical properties."
Explanation:
2. In which sentence is the term heat used correctly?
A. Heat moves from a cold cup to warm tea.
B. A thermometer measures the heat in an object.
C. The heat from the hot cup warms my hands.
D. Warm soup contains more heat than cold soup does.
Answer:
c. The heat from the hot cup warms my hands
Studying the brightness of a star can help scientist determine what part of the life-cycle a star is in. Is this true or false
Answer:
what do you mean?
Explanation:
Studying the brightness of a star can indeed help scientists determine what part of the life-cycle a star is in. The brightness of a star is directly related to its stage in the life cycle.The statement is true.
During the early stages of a star's life, it is formed from a cloud of gas and dust. As the star contracts under its own gravity, it starts to heat up and emits light. This is known as the protostar stage.
As the star continues to contract, it reaches a point where the core temperature becomes hot enough for nuclear fusion to occur. At this stage, the star enters the main sequence phase, where it will spend the majority of its life. The brightness of the star in this phase is determined by its mass. More massive stars are brighter than less massive ones.
As the star ages, it exhausts its hydrogen fuel in the core and begins to evolve. Depending on its mass, a star can become a red giant, a white dwarf, a neutron star, or even a black hole. Each of these stages has a different brightness profile.
By observing the brightness of a star over time, scientists can gather information about its age, mass, and evolutionary stage. This can provide insights into the star's life cycle and help in understanding the processes occurring within it.
Thus, studying the brightness of a star is an important tool for scientists to determine what part of the life cycle a star is in. By analyzing its brightness profile, scientists can gain valuable information about the star's age, mass, and evolutionary stage.The statement is true.
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When the temperature of the air in a hot air ballon increases, what happens to the volume of the gas?
Answer:
As the temperature increases, the gas particles absorb more heat energy. They speed up and move farther away from one another. So the increase in temperature causes an increase in volume. (Boyles Law)
Part E
In which state of matter are the particles the most spread out?
Gas has the most spread out particles.
Is fresh squeezed lemonade a homogeneous or heterogeneous mixture
Answer: This makes the lemonade a homogenous mixture
Explanation:
If the freshly squeezed lemonade is made by squeezing lemons to extract the sour juice and mixing this with water and sugar all the substances in the mixture finally created are in the same phase.
What is the correct name for Fe203?
A Iron(V) oxide
B Iron(III) oxide
C Iron(I) oxide
D Iron(II) oxide
Answer:
The answer would be B.
Explanation:
what are the intervals on the fahrenheit scale called
Fahrenheit temperature scale fâr´ənhīt˝ [key], temperature scale in which the temperature difference between two reference temperatures, the melting and boiling points of water, is divided into 180 equal intervals called degrees.
I will brainless who can answer this all pleaseeeeej
Answer:
1. FALSE
2. TRUE
3. TRUE
4. FALSE
5. FALSE
6. TRUE
7. TRUE
8. TRUE
9. TRUE
10. TRUE
Explanation:
1. Conduction occurs more readily in solids and liquids
2. Gold is used as a contact metal in the electronics industry as it is a good conductor of both electricity and heat.
3. None
4. Radiation is the fastest mode of heat transfer while conduction is the slowest mode of heat transfer
5. Heat from Sun reaches us by the process of radiation
6. None
7. It is the motion of particles that creates a form of energy called heat (or thermal) energy that is present in all matter
8. At a temperature of 0o C, the thermal energy within a given system is also zero
9. None
10. None
PLEASE MARK BRAINLIEST, THANKS <3
identify the number of bonding pairs and lone pairs of electrons in water.
Answer:
2 bonding pairs and 2 lone pairs
if one mole of na3po4·3h2o is heated extensively, how many moles of water are released?
When one mole of Na3PO4.3H2O is heated extensively, three moles of water are released.
The water molecules in Na3PO4.3H2O are called molecules of water of crystallization. These molecules are not covalently bonded to the Na3PO4 molecule. They are only loosely attached to the substance.
Strong heating will drive away these molecules of water of crystallization to give three moles of water in the product.
Hence, when one mole of Na3PO4.3H2O is heated extensively, three moles of water are released.
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what is the acceleration due to gravity of the moon
Can someone help me with this
Answer: It would be malleable, solids, luster, conductors, reactive
Explanation:
Convert 3,124,991 centimeters (cm) to miles (mi) rounding to 4 sig figs
Answer:
19.417794 mi
Explanation:
Answer:
19.41
Explanation:
how many oxygens are used per glucose molecule in glycolysis?
Answer:
0
Explanation:
How many cm of a solution of 0.100 mol dm NaOH are required to completely -3 neutralize 25.0 cm of 0.250 mol dm H3PO4?. a) Write a balanced equation for the reaction (4 marks) b) How many moles of H3PO4 need to be neutralized? (1 marks) c) How many moles of NaOH are needed to neutralize the H3PO4? (1 marks) d) How many cm of 0.100 mol dm NaOH contain the moles in question 5(©) above? (1 marks)
Answer:
Explanation:
How many cm of a solution of 0.100 mol dm NaOH are required to completely neutralize 25.0 cm of 0.250 mol dm H3PO4?.
a) Write a balanced equation for the reaction NaOH to neutralize (4 marks
?. ) 25.0 cm of 0.250 mol dm H3PO4
H3PO4 + 3NaOH----------> Na3PO4 +3 H2O
b) How many moles of H3PO4 need to be neutralized? (1 marks)
25.0 cm3 of 0.250 mol dm3 H3PO4: 1 liter has 0.25 moles. 100 ml has 0.025 moles 25 ml has o.025/4 molea or 0.00625 moles)
c How many moles of NaOH are needed to neutralize the H3PO4? (1 marks)
for every moles of H3PO4, WE NEED 3 MOLES OF NaOH. FOR 0.00625 MOLES WE NEED 3X 0.00625 =0.01875 MOLES OF NaOH
d) How many cm3 of 0.100 mol /l NaOH contain the moles in question 5(©) above? (1 marks)
1 L CONTAINS 0.100 Moles
100 ml contains 0.010Moles
we need 187.5 ml since (187.5 X 0.100)/1000=0.01875
Anyone help me answer this please anyone
Answer:
[tex]\huge\boxed{\sf Q = 5880\ Joules}[/tex]
Explanation:
Given:
m = mass = 40 g = 0.04 kg
c = specific heat constant of water = 4200 J/Kg°C
ΔT = change in temperature = T2-T1 = 60 °C - 25 °C = 35°C
Required:
Q = change in heat energy = ?
Formula:
Q = mcΔT
Solution:
Q = (0.04)(4200)(35)
Q = 5880 Joules
[tex]\rule[225]{225}{2}[/tex]
at a fixed temperature and pressure, a cylinder contains equal volumes of o2 and an unknown gas, weighing 20.0 g and 17.5 g respectively. what is the identity of the unknown gas?
At a fixed temperature and pressure, a cylinder contains equal volumes of O2 and an unknown gas. The identity of the unknown gas CO.
The number of moles of a given substance is calculated by dividing the mass by the molar mass.
The number of moles of O₂ = [tex]\mathbf{=\dfrac{20.0 \ g}{32 \ g/mol}}[/tex]
= 0.625 moles.
Based on the given assumption, at fixed temperature and pressure;
Let assume that the number of moles of the unknown gas is = 0.625 molesThe molar mass of the unknown gas can be estimated as:
[tex]\mathbf{= \dfrac{mass}{number \ of \ moles}}[/tex]
[tex]\mathbf{= \dfrac{17.5 \ g}{0.625 \ moles}}[/tex]
= 28 g/mol
Therefore, we can conclude that the unknown gas is CO.
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Can someone help me to write the ionic equation :((
Answer:
Here use this to help you
Explanation:
PLEASE HELPP!
True or False: Hydrogen is an alkali metal.
Answer: falso
Explanation:
how many protons does boron-11 atom have
Answer:
5
Explanation:
is this statement true or false? the chinese knew how to produce silk by about 2700 b.c.
Answer:
its true
Explanation:
I took the test
raw or undercooked shellfish may be contaminated with what type(s) of bacteria
vibrio vulnificus
salmonella
vibrio vulnificus and vibrio parahaemolyticus
Answer:
vibrio vulnificus and vibrio
Explanation:
Answer:
vibrio vulnificus and vibrio parahaemolyticus
plsss help I really need it:(((
Answer:
12. A
13. A
14. D
15. B
Explanation:
12. The 3rd law of motion is the force of our object being equal and opposite the other. If the Buller goes forward with force, the the gun recoils backwards with the same force.
13. There's nothing else described in the problem besides him getting kicked in the face
14. If you mive the oars forwards then the boat itself moves backwards
15. The gas helps push the rocket upwards since it goes downwards.
Why is boiling water considered a physical change
why do you think that sodium chloride has to be heated to 800c before melting, but candle wax will start to melt at 50c?
Answer:
Sodium chloride is an ionic compound which makes it stronger and have a higher melting and boiling point. Candle wax is a covalent compound so it has a low melting point.
Explanation:
PLEASE MARK AS BRAINLIEST!!!!!what is physical change
Answer:
changes that dont result in the formation of new substance with new properties.
the mixing of which pair of reactants will result in a precipitation reaction?
Answer:
NH4Br and NH4I are both soluble in water, and they don't react with each other. So this pair will not form precipitation.
NaClO4 and (NH4)2S are both soluble in water. While in water, they dissociate into Na+, ClO4-, NH4+ and S2- ions, which don't react with each other. So this pair will not form precipitation.
Ni(NO3)2 and Na2CO3 are both soluble in water. When the 2 solutions combine, NiCO3 forms. NiCO3 is not soluble in water, so it will precipitate out from the solution. This pair will result in precipitation.
K2SO4 and Cu(NO3)2 are both soluble in water. While in water, they dissociate into K+, SO42-, Cu2+ and NO3- ions, which don't react with each other. So this pair will not form precipitation.
Explanation:
Hope this helps...
