Who thought fire was one of four elements?
O A. Aristotle
O B. Marie Curie
O C. John Dalton
O D. Robert Boyle
Answer:
D Robert Boyle
Explanation:
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Answer:
Section a:
1. stratosphere
2. radio waves
3. nitrogen, oxygen
4. humidity
5. smoke, fog
Section b:
1. ozone layer
2. stratosphere
3. carbon dioxide (CO2)
4. smoke
5. tropical areas
Section c:
1. false, it is clear
Hope those help and are all correct
What has more particles: a mole of hydrogen or a mole of uranium?
Answer
hydrogen
Explanation:
Formulate a hypothesis based on something recently observed.
And How could this hypothesis be tested?
Answer:
If garlic repels fleas, then a dog that is given garlic every day will not get fleas. Bacterial growth may be affected by moisture levels in the air. If sugar causes cavities, then people who eat a lot of candy may be more prone to cavities.
Explanation:
how many structures are possible for a square planar molecule with a formula of ax3y?
Answer:
Explanation:
Depending upon the relative arrangements of XandY X a n d Y , the square planar molecule AX3Y A X 3 Y shows only the following structure: Hence, only one structure is possible for a square planar molecule with a formula of AX3Y A X 3 Y .
Do cells have atoms?
Answer:
Ye? everything is made up of atoms so sure
why is it hotter in the summer and colder in the winter?
Answer: During the summer, the sun's rays hit the Earth at a steep angle. ... Also, the long daylight hours allow the Earth plenty of time to reach warm temperatures. During the winter, the sun's rays hit the Earth at a shallow angle. These rays are more spread out, which minimizes the amount of energy that hits any given spot.
Please help me, trying to get all my hw done
Answer:
C. size and shape
Explanation:
Physical properties such as size, shape, color, density, magnetism or the
ability to sink or float can be used to separate the substances in a mixture..
Filtration is when matter is passed through a filter and the larger particles
are separated out. Magnets can be used to separate magnetic matter from
non-magnetic matter in a mixture. Objects that float when placed in water
can be separated from those that don’t by placing the mixture in water.
Write the complete electron configuration using the diagonal rule for strontium.
which describes an attribute of nonrenewable resources
Answer:
atributes of nonrenewable recources are things you cant re use after 1 use like gas
Explanation:
Answer: the answer is b. Are unlimited
Explanation:
what is the nature of the p-o bond in phosphorus pentoxide (p2o5)?
Answer:
the nature of the bond is covalent.
covalent bonds are bonds between 2 NON-METAL elements. since phosphorus and oxygen are both non-metals, the bond formed between them is covalent.
hope this answers your question!
Boron and antimony are good elements to use as
Answer: Semiconductors
Explanation:
Which choice describes an organism found in the under story of a rain forest?
thick, woody vines
bacteria
very tall trees
palms and other small trees
Answer:
Palms and other small trees
The choices which describes an organism found in the under story of a rain forest are bacteria, thick and woody vines.
What is under story of a rain forest?The understory is a layer of young trees, short species of trees, shrubs, and soft-stemmed plants that lies several meters beneath the canopy's bottom. The understory differs greatly from one rainforest to the next.
The organism that is found in the under story of a rain forest is bacteria and very small plants, thick and woody vines.
Hence organism that is present in the understory are bacteria, thick and woody vines.
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How do chemists predict the shapes of molecules?
Due to the repulsion between electrons, valence electrons will be arranged as close to each other as possible.
Due to the attraction between electrons, valence electrons will be arranged as close to each other as possible.
Due to the repulsion between electrons, valence electrons will be arranged as far apart from each other as possible.
Chemists can't predict the shape of molecules, because the attractive forces between valence electrons are unpredictable.
A. Due to the repulsion between electrons, valence electrons will be arranged as close to each other as possible.
The approximate shape of a molecule can often be predicted by using what is called the valence-shell electron-pair repulsion (VSEPR) model.Electrons in bonds and in lone pairs can be thought of as a charge cloud that repels one another and stay as far apart possible, thus causing molecules to assume specific shapes.The shape of a molecule is determined by the location of the nuclei and its electrons.Therefore, the correct option is A.
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BRAINLIEST TO FIRST RIGHT ANSWER
Use the key above to interpret the following incomplete chemical reaction.
Select the statements at apply in order to complete the model. (Choose 3)
A) The number of atoms in the products must be equal to the reactants.
B) One diatomic oxygen should be removed from the reactant side.
C) One unbonded carbon atom should be added to the product side of the equation
D) One carbon atom and two oxygen atoms are needed to balance the equation.
E) One carbon dioxide molecule should be added to the product side of the equation.
Answer:
Carbon dioxide molecule
Answer:a , d ,e
Explanation:
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Is a change in color when combining two substances normally a sign of a chemical change or a physical change?
Answer:
Change in colour is a chemical change.
Explanation:
Because when two substances combine chemically, they create (a) new substance(s) that have/has different molecular structures from the parent substances, thus mostly likely absorb and reflect light in different ways.
"uses for simple machines" whats a piano that needs to be moved up to a third floor apartment
Answer:
Pulley
Explanation:
You can't the piano up the stairs, you need to something to bring it up
5. Scientists always develop a plan when they try to learn something about our natural world. Which
sequence correctly shows the steps scientists follow in their plan?
A. make observations, develop an idea, obtain evidence, suggest an explanation
B. obtain evidence, suggest an explanation, develop an idea, make observations
C. suggest an explanation, obtain evidence, make observations, develop an idea
D. develop an idea, suggest an explanation, obtain evidence, make observations
Why weren’t scientists initially concerned that the ocean absorbs excess carbon dioxide?
Why scientists weren’t initially concerned that the ocean absorbs excess carbon dioxide was because they saw carbon dioxide as a pollutant
What is a pollutant?Generally, A pollutant is a material found in amounts that are harmful to organisms or exceed an environmental quality standard.
In conclusion, scientists saw carbon dioxide as a major air pollutant, and the water was helping by absorbing it.
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Find the percent composition of OXYGEN in Manganese (III) nitrate, Mn(NO3)3.
Answer:
59.8%
Explanation:
First find the Mr of manganese (III) nitrate.
Mr of Mn(NO₃)₃ = 54.9 + (14 × 3) + (16 × 3 × 3) = 240.9
Since we have to find the percentage composition of oxygen, we need to find the Mr of oxygen in the compound, which is:
Mr of (O₃)₃ = (16 × 3) × 3 = 144
Now we can find percentage composition / percentage by mass of oxygen.
% composition = [tex]\frac{Mr\ of\ oxygen\ in\ compound}{Mr\ of\ compound}[/tex] × 100
% composition = [tex]\frac{144}{240.9}[/tex] × 100 = 59.776%
∴ % compostion of oxygen in maganese(III)nitrate is 59.8% (to 3 significant figures).
Hurry. NO Spam! Write the neutralization reaction that occurs between HF and LiOH.
Answer:
HF + LiOH = LiF + H2O.
Explanation:
Hydofluoric acid is a weak acid the solution would be slightly basic due to the following equilibrium (condition in the course of a reversible chemical reaction in which no net change in the amounts of reactants and products occurs.)
Hope that helps. x
Find the molar mass of iron (III) nitrate, Fe(NO3)3
Answer:
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As atoms get smaller,valance electrons are getting closer or farther away from the nucleous.The force of attraction is stronger o weaker so it takes more or lesss energy to remove electrons?
Explanation:
Electrons are closer to the nucleus are in filled orbitals and are called core electrons. More energy which in nucleus called nuclear strOng energy to remove electron thars why its also a way harder too..
How much heat is required to warm 50.0 g of ice from -10.0oC to 0.00oC, melt the ice, warm the water from 0.00oC to 100.0oC, boil the water, and heat the steam to
120.0oC ?
a 209,000 J
b 199,000 J
c 1.67 x 106 J
d 152,000 J
The total heat required to convert the ice to steam is 155,000 J.
The given parameters:
Mass of the ice, m = 50 gInitial temperature of the ice, t = -10 ⁰CFinal temperature of the ice, T = 0⁰C, 100⁰C and 120⁰CSpecific heat capacity of water = 4.184 J/g⁰CHeat of fusion of ice, = 333.55 J/gHeat of vaporization, = 2,230 J/gThe heat required to raise the temperature to 0⁰C is calculated as;
[tex]Q = mc\Delta t\\\\Q_1 = 50 \times 4.184 \times (0 - (-10))\\\\Q_1 = 2092 \ J[/tex]
The heat required to melt the ice is calculated as follows;
[tex]Q_2 = mL_f\\\\Q_2 = 50 \times 333.55 \\\\Q_2 = 16,677.5 \ J[/tex]
The heat raise the temperature to 100⁰C is calculated as;
[tex]Q_3 = 50 \times 4.184 \times (100 - 0)\\\\Q_3 = 20,920 \ J[/tex]
The heat required to boil the water is calculated as follows;
[tex]Q_4 = mL_v\\\\Q_4 = 50 \times 2230\\\\4_4 = 111,500 \ J[/tex]
The heat raise the temperature to 120⁰C is calculated as;
[tex]Q_5 = 50 \times 4.184 \times (120 - 100)\\\\Q_5 = 4,184 \ J[/tex]
The total heat required is calculated as follows;
[tex]Q_t = Q_1 + Q_2 + Q_3 + Q_4 + Q _5 \\\\Q_t = 2092 + 16,677.5 + 20,920 + 111,500 + 4,184\\\\Q_t = 155,373.5 \ J\\\\Q_t \approx 155,000 \ J[/tex]
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A student is trying to classify an unidentified, solid gray material as a metal or a nonmetal. Which question will best help the student classify the material?.
The question that will best help the student to classify the material is; "is the material malleable or ductile?"
Generally, materials can be classified as metals or non metals. There are properties that are particular to metals and there are properties that are particular to nonmetals and these properties can be used to identify each one of the materials.
The question that will best help the student to classify the material is; "is the material malleable or ductile?" These metallic properties.
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Missing parts;
A student is trying to classify an unidentified, solid gray material as a metal or a nonmetal. Which question will best help the student classify the material? A. Is the material malleable or ductile? B. Does the material feel hard to the touch? C. Will the material float in water? D. Does the material feel rough or smooth?
Which statement describes how a substance melts?(1 point) Molecules in the substance gain kinetic energy and then become less tightly bound to each other. Molecules in the substance gain kinetic energy and then become less tightly bound to each other. Molecules in the substance lose kinetic energy and then become more tightly bound to each other. Molecules in the substance lose kinetic energy and then become more tightly bound to each other. Molecules in the substance lose kinetic energy and then become less tightly bound to each other. Molecules in the substance lose kinetic energy and then become less tightly bound to each other. Molecules in the substance gain kinetic energy and then become more tightly bound to each other. Molecules in the substance gain kinetic energy and then become more tightly bound to each other.
Answer:
Molecules in the substance gain kinetic energy and then become less tightly bound to each other.
Explanation:
According to the forces of attraction , for a substance to melt molecules in the substance gain kinetic energy and then become less tightly bound to each other.
What are forces of attraction?Forces of attraction is a force by which atoms in a molecule combine. it is basically an attractive force in nature. It can act between an ion and an atom as well.It varies for different states of matter that is solids, liquids and gases.
The forces of attraction are maximum in solids as the molecules present in solid are tightly held while it is minimum in gases as the molecules are far apart . The forces of attraction in liquids is intermediate of solids and gases.
The physical properties such as melting point, boiling point, density are all dependent on forces of attraction which exists in the substances.
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Which of the following is true of grinding during
digestion?
A. The process of grinding is a physical change
that takes place in the mouth during digestion.
B. The process of grinding is a chemical change
that takes place in the mouth during digestion.
C. The process of grinding is a physical change
that takes place in the small intestine during
digestion
D. The process of grinding is a chemical change
that takes place in the small intestine during
digestion
The process of grinding is a physical change that takes place in the mouth during digestion.
GRINDING:Grinding is one of the processes that occur during the digestion of food molecules into simpler substances.
Grinding of food molecules occurs in the mouth with the aid of the teeth, which is used to chew.
However, the process of grinding is a physical change because it does not result into the formation of new substances or change the chemical constituents of the food.
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What is the source of energy in nuclear weapons?
O A. Combustion
O B. Fusion
O C. Gravity
O D. Fission
Answer:
D. Fission
Explanation:
Induced fission is used to generate nuclear power and for weapons. The products formed during fission gain kinetic energy. It is this energy that is harnessed in nuclear power stations.
Is bleach liquid starch?
Yes or No
Answer:
O it's not
Explanation:
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How many molecules of NO2 are in 0.36 moles?
Answer:
1 mol contains 6.022*10^23 molecules 0.36 moles contain 0.36 * 6.022*10^23 = 2.2 *10^23 molecules
Explanation: