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
Learn more about the Rydberg formula; https://brainly.com/question/17753747
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:
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.
Learn more about dissolving here: https://brainly.com/question/17030000
Learn more: https://brainly.com/question/25937667
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.
Learn more about periodic table,here:
https://brainly.com/question/11155928
#SPJ2
So if you take an egg and cook it, is it still a baby chicken?
When the egg first forms it's only one cell, and is fertilized as it moves down the oviduct to be laid
__________________________________________________________
this point it's technically an embryo : though it doesn't look like a baby chick
___________________________________________________________
o0o0o0o0o0o0o0o0o0o0o0o0o0o0o0o0o0o0o0o0o0o0o0o0o0o0o0o0
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]
4. If 100.0 g of water is cooled from 25.3°C to 16.9°C, what quantity of
energy has been transferred from the water?
Answer:
Dived the numbers by each other
Explanation:
25.3/19.9
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.
What is the enthalpy of reaction for the decomposition of calcium carbonate? CaCO3(s) Right arrow. CaO(s) CO2(g) kJ.
The enthalpy of reaction for the decomposition of calcium carbonate is 177.4 KJ/mole .
We know that the enthalpy of reaction can be obtained from the enthalpy of formation of the reactants and that of the products using the formula;
ΔHrxn = ΔHf (products) - ΔHf (reactants)
The heat of formation of the species are as follows;
ΔHf (CaCO3(s)) = −1206.9 KJ/mol
ΔHf (CaO(s)) = - 636 KJ/mole
ΔHf (CO2(g)) = -393.5 KJ/mole
ΔHrxn = [( -393.5 KJ/mole ) + ( - 636 KJ/mole)] - [ −1206.9 KJ/mol]
ΔHrxn = 177.4 KJ/mole
Learn more: https://brainly.com/question/13164491
Answer:
First one is 656.3 and second is endothermic.
Explanation:
Edge Thermochemical Equations assignment
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%
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.
How does thermal energy flow?
Answer:
Thermal energy typically flows from a warmer material to a cooler material.
Explanation:
HELP ME PLEASE HURRY
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.
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
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 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:
Which shows the weight of an atom?
atomic mass
atomic number
chemical symbol
none of the above
Answer:
The atomic mass
Explanation:
Answer: atomic mass
what was johann dobereiner contribution to the periodic table
Answer:
he introduced triads of similar chemical properties in periodic table.
Explanation:
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
answer this bs for me pls
Answer:
B.chlorine ,Cl2 is the one
pls help :)))))))pop
Answer:
c-a-b
Explanation:
what is the mass of 3.0 x x times 10^23 atoms of neon?
Answer:
10.09 grams
Explanation:
First you need to know the number of moles you are dealing with.
If you know that each mole has 6.022x10²³ of something (in this case of atoms), you can divide 3x10²³ atoms of neons by 6.022x10²³ to obtain the number of moles.
You have 0.5 moles of Neon, so then by the periodic table, you see that the molar mass of neon is 20.18g/mol, so by each mole you have 20.18 grams of neon. Multiply 20.18 grams by 0.5 moles and you got 10.09 grams of Neon
which statement describes how the binary ionic compound cacl2 is named?
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.
100 PIONTSSSS PLZ HELP
Draw the correct structural formula for the following molecules
Answer:
Explanation:
how do u draw on here
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.
Learn more about electrons here: brainly.com/question/25674345
#SPJ2
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
I need help ASAP my final 20 points!!!
Please helppp asapppp due soon ignore the answers i put in their wrong
__H2 + __SO2 —> __H2S + __H2O identify the proper coefficients