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:
which of the following types of radiation can be blocked with only a sheet of paper?
beta decay, gamma decay, they are equally dangerous, alpha decay
Answer:
Alpha decay
Explanation:
Alpha decay can be blocked with only a sheet of paper.
Extra info : -
In general, alpha particles have a very limited ability to penetrate other materials. In other words, these particles of ionizing radiation can be blocked by a sheet of paper, skin, or even a few inches of air.
Hello there!
Alpha decay can be blocked with only a sheet of paper.Gamma rays can only be blocked with something thick and dense.Beta rays can be blocked with something less dense, but thicker than paper.Hope this helps. Let me know if you have any questions.
~GracefulGirlie :)
Good luck on your assignment.
what is mass of sodium hydroxide NaOH is present in 0.25 mole of sodium hydroxide
pls be quick
Finding molar mass of NaOH
We know that
Molar mass of Sodium (Na) = 23 g/mol
Molar mass of Oxygen (O) = 32 g/mol
Molar mass of Hydrogen (H) = 2 g/mol
So,
Mass of 1 mole of NaOH
=> 1 × 23 + 1 × 16 + 1 × 1
=> 23 + 16 + 1
=> 40 g/mol
Now,
Mass = 40 × 0.25
Mass = 10 g
How does thermal energy flow?
Answer:
Thermal energy typically flows from a warmer material to a cooler material.
Explanation:
carbon dioxide fire extinguishers are designed for which types of fuels
Answer:
Carbon Dioxide is a non-flammable gas that extinguishes fire by displacing oxygen
CO2s are designed for Class B and C (flammable liquid and electrical) fires only.
why is it impossible to have an undiscovered element that would fit between sodium and magnesuim
Answer:
Sodium has 11 protons and Magnesium has 12. The way that the periodic table is set up doesn't allow for any elements to be in between. The element would have to have 11.5 protons, which is impossible
Structure of periodic table is designed in a way that successive elements have difference of 1 electron and proton as sodium and magnesium have 11 and 12 protons respectively there is no space for any other element.
What is periodic table?Periodic table is a tabular arrangement of elements in the form of a table. In the periodic table, elements are arranged according to the modern periodic law which states that the properties of elements are a periodic function of their atomic numbers.
It is called as periodic because properties repeat after regular intervals of atomic numbers . It is a tabular arrangement consisting of seven horizontal rows called periods and eighteen vertical columns called groups.
Elements present in the same group have same number of valence electrons and hence have similar properties while elements present in the same period show gradual variation in properties due to addition of one electron for each successive element in a period.
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Imagine you have two beakers. Both beakers are filled with the same amount of water. The water in both beakers is the same temperature as well. You add 50 g of Substance A to the first beaker and 50 g of Substance B to the second beaker. After stirring both beakers, there is a small pile of Substance A at the bottom of the first beaker. None of Substance B is visible in the second beaker. Which of the following statements is true?
A. Substance B is not soluble in water
B. Substance A is more soluble in water than Substance B
C. Substance A is less soluble in water than Substance B
D. Substance A is not soluble in water
Substance A is less soluble in water than Substance B.
In this experiment, we can see that small amount of substance A is present at the bottom of the beaker which means that some amount of substance A does not dissolve in water.
While on the other hand, no substance B is present at the bottom of beaker which shows that all the substance B is dissolved in water so we can made a conclusion that Substance A is less soluble in water than Substance B.
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How many atoms le aluminum are in this compound
__H2 + __SO2 —> __H2S + __H2O identify the proper coefficients
What happens in cellular respiration?
The answer would be B.
When glucose reacts with oxygen, it forms an ATP that is used by the given cell. Co2 and h2O are the byproducts.
Why does atomic radii decrease as you move from the left to right across the period
Answer:
This is because, within a period or family of elements, all electrons are added to the same shell.
When we move from left to right across the periodic table, we can see that the atomic radii keeps decreasing. This is because, as you move from left to right, the nucleus gains protons. The atomic number increases and hence the valence electron will feel more attracted towards the nucleus & the atomic radii will decrease.
[tex]\mathbb{MIREU}[/tex]
What are some examples of a physical change? (list more than 2 examples)
Answer:
Examples of physical change include changes in the size or shape of matter. Changes of state, for example, from solid to liquid or from liquid to gas, are also physical changes. Some of the processes that cause physical changes include cutting, bending, dissolving, freezing, boiling, and melting.
Explanation:
I hope this helps
What are the compounds that you can find in mayonnaise
HEY!
Mayonnaise is an oil in water (O/W) emulsion; ingre- dients are primarily vegetable oil, egg yolk, sodium chloride, water and vinegar. Its relative stability towards microbial spoil- age has been attributed to the high salt content (in the water phase) and low pH, due to the vinegar.
thank me later
carryonlearing
which statement describes how the binary ionic compound cacl2 is named?
True or false? The empirical formula of a compound is the simplest formula that shows the numerical relationship of the elements in the compound.
Answer:
True
Explanation:
the empirical formula usually shows us the atoms' symbols and then how much of them are present in this certain compound. For example there is H2O
Look at the diagram of metallic bonding. The light blue area represents a sea of... what?
Answer:
try elcetrons
Explanation:
if not then i'm sorry
The light blue area represents electrons.
What is an electron?
An electron is a negatively charged subatomic particle. It can be either free (not attached to any atom) or bound to the nucleus of an atom. Electrons in atoms exist in spherical shells of various radii, representing energy levels. The larger the spherical shell, the higher the energy contained in the electron.
What is the role of electrons?
Electrons play an essential role in numerous physical phenomena, such as electricity, magnetism, chemistry and thermal conductivity, and they also participate in gravitational, electromagnetic and weak interactions.
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Estimate the pressure of 16.25 moles of methane on a 10l container at 300k. Round to the nearest atmosphere
Answer:
The pressure of 16.25 moles of methane = 40 atm
Explanation: there you go
what was johann dobereiner contribution to the periodic table
Answer:
he introduced triads of similar chemical properties in periodic table.
Explanation:
the process by which glucose is converted to starch is known as
Answer:
polymerization
Explanation:
Glucose is converted into starch by the process called polymerization. In polymerization, several simple and soluble molecules of glucose are put together to form a complex, insoluble molecule of starch.
Glucose is soluble , so it is converted to starch so that it can become insoluble and hence it cannot escape from cell , thus it can also be stored.
Here's the question ~
Heat treatment of muscular pain involves radiation of wavelength of about 900 nm (nm = 10-⁹ m). which spectral line of H - atom is suitable for this purpose ?
[ RH = 1 × 10⁵ cm-¹ ]
[ h = 6.6 × 10-³⁴ Js ]
[ c = 3 × 10⁸ m/s ]
Thanks for Answering !
Using the Rydberg formula, the spectral line of H - atom is suitable for this purpose is Paschen, ∞ → 3.
Using the Rydberg formula;1/λ = RH(1/nf^2 - 1/ni^2)
Given that;
λ = wavelength
RH = Rydberg constant
nf = final state
ni = initial state
When final state = 3 and initial state = ∞Then;
1/λ = 1 × 10^7 m-1 (1/3^2 - 1/ ∞^2)
1/λ = 1 × 10^7 m-1 (1/3^2 )
λ = 900 nm
Hence, the correct answer is Paschen, ∞ → 3
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what is actually chemistry
Answer:
Chemistry is the branch of science that deals with the properties, composition, and structure of elements and compounds, how they can change, and the energy that is released or absorbed when they change.
Answer:
Well my teacher said a more complex way he said chemistry is the science that deals with the properties, composition, and structure of substances.
Explanation:
Consider the reaction below. H2PO4â€"" H2O Right arrow. H3O HPO42â€"" Which of the following is a baseâ€""conjugate acid pair? H2O and H3O H2O and H2PO4â€"" H2PO4â€"" and HPO42â€"" H2PO4â€"" and H3O.
Taking into account the Brønsted-Lowry acid-base theory, a base/conjugate acid pair is H₂O/H₃O⁺.
The Brønsted-Lowry acid-base theory (or the Brønsted-Lowry theory) identifies acids and bases based on whether the species accepts or donates protons or H⁺.
According to this theory, acids are proton donors while bases are proton acceptors. That is, an acid is a species that donates an H⁺ proton while a base is a chemical species that accepts an H⁺ proton from the acid.
So, reactions between acids and bases are H⁺ proton transfer reactions, causing the acid to form its conjugate base and the base to form its conjugated acid by exchanging a proton.
In other words, a conjugate base is an ion or molecule resulting from the acid that loses the proton, while a conjugate acid is an ion or molecule resulting from the base that gains the proton:
acid + base ⇄ conjugate base + conjugate acid
In this case, you know:
H₂PO₄ + H₂O → H₃O⁺ + HPO₄⁻
H₂PO₄ behaves like acid because donates an H⁺ proton while H₂O behaves like base because accepts an H⁺ proton from the acid.
So, H₃O⁺ is the conjugate acid of the H₂O and HPO₄⁻ is conjugate base of H₂PO₄.
In summary, a base/conjugate acid pair is H₂O/H₃O⁺.
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The characteristics of two different types of reactions are shown below:
Reaction A: Electrons are gained by the atoms of an element.
Reaction B: Protons are lost by the atom of an element.
Which statement is true about the atoms of the elements that participate in the two reactions?
Their identity changes in both Reaction A and Reaction B.
Their identity changes in Reaction A but not in Reaction B.
Their identity changes in Reaction B but not in Reaction A.
Their identity remains the same in both Reaction A and Reaction B.
Answer:
D is correct
Explanation:
Answer:
A
Explanation:
Electrons are gained by the atoms. There is no change in the nucleus of the atom and the number of protons remains identical.
name any two chemical required for preparation of ammonia gas
Answer:
Ammonium chloride and slacked lime
Explanation:
We can generate ammonia gas in the research centre by slowly heating ammonium chloride (NH4Cl) and slaked lime [Ca(OH)2]. Ammonia gas is lighter than air, requiring its accumulation by the descending displacement of air.
people tint their car windows to stop what
Answer:
Reflection
Explanation:
Answer:
b
Explanation:
The intermolecular forces between polymer molecules are strong, so these substances are __________ at room temperature. What word completes the sentence?
Answer:
I want to say
Stronger
100 PIONTSSSS PLZ HELP
Draw the correct structural formula for the following molecules
Answer:
Explanation:
how do u draw on here
a 7.221 g sample of a compound contains 1.990 g carbon, 2.341 g hydrogen, and the rest is oxygen. Determine the
percent composition of the compound
Answer:
17.19%
Explanation:
mass of oxygen = 7.221 - (1.990 + 2.341)
= 2.890g
Empirical formula of the compound
For carbon,
1.990/12 = 0.1658
For hydrogen,
2.341/1 = 2.341
For oxygen,
2.890/16 = 0.1806
0.1658 ÷ 0.1658 = 1
2.341 ÷ 0.1658 = 14.11
0.1806 ÷ 0.1658 = 1.089
Empirical formula of the compound= CH14O
Molar mass= (1×12) + (14×1) + (1×16)
= 12+14+16
= 42g/mol
percentage composition= 7.221/42 × 100
= 17.19%
answer this bs for me pls
Answer:
B.chlorine ,Cl2 is the one
Like the success of animals, the success of plants is limited based on the resources available to each individual. In the tropical
rainforest, plants are especially limited by the spate they have available to grow and reproduce. Which of these statements
describes a way that limited space will impact
the success of a plant in the rainforest? (SC.7.L.17.3)
A plant without enough space will face increased predation from herbivores
a
O A plant without enough space will not have as many parasites and diseases.
3
A plant without enough space will be more likely to be impacted by air quality
A plant without enough space will not be able to capture enough light to grow.
A plant without enough space to grow may be impacted by inadequate air as well as light for proper growth.
The competition for space in the tropical rainforest has impacts on two processes:
Light for photosynthesisAir for growthLight is very important for photosynthesis and the overall well-being of plants. In a tight space, light and air become limited. This means that plants growing in such a space will not be able to photosynthesize optimally.
Plant roots need air to function properly and when becomes inadequate, the entire plant becomes negatively impacted.
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