Answer:
it's a chemical Element
Explanation:
symbol He
atomic number 2.
Given the wavelength of the corresponding emission line, calculate the equivalent radiated energy from n = 4 to n = 2 in both joules and electron volts. Also, calculate the frequency of the wave. λ (Á) = 4861, ƒ(Hz), E(J), E(eV)
Explanation:
It is given that,
Initial orbit of electrons, [tex]n_i=4[/tex]
Final orbit of electrons, [tex]n_f=2[/tex]
We need to find energy, wavelength and frequency of the wave.
When atom make transition from one orbit to another, the energy of wave is given by :
[tex]E=-13.6(\dfrac{1}{n_f^2}-\dfrac{1}{n_i^2})[/tex]
Putting all the values we get :
[tex]E=-13.6(\dfrac{1}{(4)^2}-\dfrac{1}{(2)^2})\\\\E=2.55\ eV[/tex]
We know that : [tex]1\ eV=1.6\times 10^{-19}\ J[/tex]
So,
[tex]E=2.55\times 1.6\times 10^{-19}\\\\E=4.08\times 10^{-19}\ J[/tex]
Energy of wave in terms of frequency is given by :
[tex]E=hf[/tex]
[tex]f=\dfrac{E}{h}\\\\f=\dfrac{4.08\times 10^{-19}}{6.63\times 10^{-34}}\\\\f=6.14\times 10^{14}\ Hz[/tex]
Also, [tex]c=f\lambda[/tex]
[tex]\lambda[/tex] is wavelength
So,
[tex]\lambda=\dfrac{c}{f}\\\\\lambda=\dfrac{3\times 10^8}{6.14\times 10^{14}}\\\\\lambda=4.88\times 10^{-7}\ m\\\\\lambda=488\ nm[/tex]
Hence, this is the required solution.
f(Hz) = 6.17 × 10¹⁴
E(J) = 4.09 × 10⁻¹⁹
E(ev) = 2.56
A scuba diver’s air tank contains oxygen, helium, and nitrogen at a total pressure of 205 atmospheres. The partial pressure of nitrogen is 143 atmospheres, and the partial pressure of helium is 41 atmospheres. What is the partial pressure of oxygen in the tank?
answer is 20
explanation: total Pressure = 205
partial pressure of N = 143
partial pressure of He = 41
total pressure = partial pressure of N + partial pressure of O + partial pressure of He
partial pressure of O = 205 - 185 = 20
Answer:
20
Explanation:
what’s the reaction type of aqueous magnesium sulfate + aqueous sodium carbonate?
Answer: Double displacement reaction
Explanation:
Double displacement reaction is defined as the reaction where exchange of ions takes place.
The salts which are soluble in water are designated by symbol (aq) and those which are insoluble in water and remain in solid form are represented by (s) after their chemical formulas.
The chemical reaction between aqueous magnesium sulfate and aqueous sodium carbonate is represented as:
[tex]MgSO_4(aq)+Na_2CO_3(aq)\rightarrow Na_2SO_4(aq)+MgCO_3(s)[/tex]
A sample of O2 gas is collected over water at 25oC at a barometric pressure of 751 torr. The vapor pressure of water at 25oC is 23.8 torr. What is the partial pressure of the O2 gas in the sample
Answer:
727.7 torr
Explanation:
Since the gas was collected over water, it is likely to be saturated with water vapour and the total pressure is given as;
Ptotal = Pgas + Pwater
From the question;
Ptotal = 751 torr
Pgas = ?
Pwater = 23.8 torr
Making Pgas subject of equation, we have;
Pgas = Ptotal - Pwater
Pgas = 751 torr - 23.8 torr
Pgas = 727.7 torr
Select the correct answer.
What is the reason for heat transfer from one substance to another
Answer:
Difference in temperature.
Explanation:
Conduction is the movement of heat energy through a substance or from one substance to another by direct contact of atoms and molecules. Heat moves directly from one molecule to another. The heat energy speeds up the movement of the atoms and they collide with other molecules setting them into faster motion.
What substance does a neutral substance release?
Answer:
Neutral substance is a substance that show no acid or base properties.
Explanation:
Neutral substance is a substances that show no acid or base properties, has an equal number of hydrogen and hydroxyl ions and does not change the color of litmus paper.
Answer:
They release no substance
Explanation:
Since the substance is neutral, nothing will be released from it.
How much heat is needed to raise the temperature of water with mass of 27.0 g at 20.0°C to 45.0°C?
Answer:
2835 J
Explanation:
Take the specific heat capacity of water as 4.2 J/ g°C.
Energy (heat) = mass x specific heat capacity x change in temperature
(E= mcΔT)
E = 27 x 4.2 x (45-20)
E = 2835 J
What's the valency of sulphur for Na2SO3
Explanation:
What are the two oxidation states of sulphur in sodium thiosulphate ? In thiosulphate, two sulphurs have oxidation state of -2 and +6. (as per suggestions). Sulphur bonded to three oxygen is considered to have +6 (Sulphur A) and other sulphur has -2 (Sulphur B).
The freezing point of pure chloroform is -63.5°C, and its freezing point depression constant is 4.07°C•kg/mol. If the freezing point of a solution of benzoic acid in chloroform is -70.55°C, what is the molality of this solution? 0.58 m 1.7 m 16 m 17 m
Answer: The molality of this solution is 1.7 m
Explanation:
Depression in freezing point:
[tex]T_f^0-T^f=i\times k_f\times m[/tex]
where,
[tex]T_f[/tex] = freezing point of solution = [tex]-70.55^0C[/tex]
[tex]T_f^0[/tex] = freezing point of pure chloroform = [tex]-63.5^0C[/tex]
[tex]k_f[/tex] = freezing point constant of benzene = [tex]4.07^0Ckg/mol[/tex]
m = molality
i = Van't Hoff factor = 1 (for non-electrolyte)
[tex]-63.5-(-70.55)^0C=1\times 4.07^0Ckg/mol\times m[/tex]
[tex]7.05=1\times 4.07^0Ckg/mol\times m[/tex]
[tex]m=1.7[/tex]
Thus the molality of this solution is 1.7 m
If the compound beryllium chloride (BeCly) has no lone pairs, it would take which shape?
A. Trigonal blpyramid
B. Octahedral
OC. Trigonal planar compound
D. Linear compound
Answer:
Liner shape
Explanation:
Because BeCl2 has 2 bond pair and no lone pair it means it will have liner shape and 180 degree angle.
Answer:
liner compound
Explanation:
Calculate the pOH and pH of a solution which contains 0.001 M NaOH. Assume 100% ionization. (Need an in-depth explanation with formulas please)
Answer:
pH: 11
pOH: 3
Explanation:
NaOH is a strong base which means that it dissociates completely in water. It will break apart into Na⁺ and OH⁻ ions.
NaOH ⇒ Na⁺ + OH⁻
Because NaOH dissociates completely into its respective ions in water, the moles of NaOH is equal to the moles of hydroxide ions. So, [OH⁻] = 0.001 M.
Now to find the pOH, use the formula pOH = -log[OH⁻].
pOH = -log[OH⁻]
= -log(0.001)
= 3
The pOH of the solution is 3.
To find the pH, subtract the pOH from 14 since pH + pOH = 14.
14 - 3 = 11
The pH of the solution is 11.
Hope that helps.
Briefly explain how magnetic behavior is related to the arrangement of valence electrons in the outer orbitals
Answer:
Elements with unpaired valence electrons in the outer orbital are paramagnetic. Elements that are predicted to exhibit paramagnetic behavior may exhibit ferromagnetic behavior. Elements that contain only paired valence electrons are diamagnetic.
An ionic bond is the attraction between _____.
Answer:
oppositely charged ions in a chemical compound
Explanation:
Answer:
Between ions
Explanation:
A substance contains 23.0 g sodium, 27.0 g aluminum, and 114 g fluorine. How many grams of sodium are there in a 102-g sample of the substance? Select one: a. 4.43 g b. 23.0 g c. 14.3 g d. 102 g e. None of these
Answer:
E. None of the above
Explanation:
Landfills are one source of CO2. As garbage decomposes, it releases CO2 into the air. Can you think of at least
one way that humans can reduce the amount of trash they dump in landfills?
Answer:
Recycling and reuse of materials
Explanation:
One of the greatest problems facing the human population is the problem of solid waste disposal. The menace of solid waste disposal has led to the idea of landfills. Land fills are depressions on the earth surface prepared for the purpose of solid waste disposal.
The most important approach towards solid waste disposal is the idea of recycling of materials. A material can be collected after use and processed into the same material or serve as a precursor in another manufacturing process. This means that no waste is generated as the materials which are supposed to be disposed of as solid waste are processed into other useful materials. This will reduce the volume of solid wastes generated that may need to be disposed in a landfill.
Answer:
There are many ways to reduce the amount of trash sent to landfills: Recycle as much as possible. Limit disposable products, and use reusable ones whenever possible. Reuse, sell, or pass along old items instead of throwing them away.
Explanation: PLATO
Answer the following questions:
1. Define a compound. State three points of evidence to show that sodium chloride is a compound.
2. When Iron powder and Sulphur powder were mixed together and heated strongly, a substance A was formed. When did. Hydrochloric acid was added to substance A, the gas B was evolved.
a) What is A and what type of substance is it?
b) Name the gas B. State one characteristic property of gas B.
c)Is the reaction of Iron and Sulphur powder a chemical change or a physical change.
Answer the question according to the class 9th student.
Answer:
1. A compound is a group of elements that cannot be separated by physical methods.
NaCl is a compound becuse it cannot be separated by physical methods.
It consists of postive and negative ions.
It can be separated only by chemical reactions.
2. (a) A is a mixture of iron and sulphur and it is in liq form.
(b) Gas B is hydrogen gas and it has sharp pungent irritating smell.
(c) It is a physical change.
Explanation:
Marking BRAINLIEST!! - Chlorine reacts with methane to form gaseous hydrogen chloride and chloromethane according to the following equation: Cl2 (g) + CH4 (g) → HCl (g) + CH3Cl (g) If 100 mL of chlorine reacted with excess methane at constant pressure and temperature, what volume of chloromethane would be formed?
Answer:
the answer for the question is 40 mL
What are indicators? How methyl orange and phenolphthalein changes their colour in acidic and basic solutions? How litmus paper changes its colour in different solutions?
Answer:
See the answer below
Explanation:
In chemistry, indicators are substances that are capable of changing colors with respect to the pH. Each indicator has its characteristic color in acidic pH and another characteristic color in alkaline pH.
Methyl orange indicator appears red in acidic solution and yellow in basic solutions. Phenolphthalein is usually colorless in acidic solutions and appears pink in basic solutions. A red litmus paper will turn blue in alkaline solutions while a blue litmus paper will turn red in acidic solutions.
A 36.0−g sample of an unknown metal at 99°C was placed in a constant-pressure calorimeter containing 70.0 g of water at 24.0°C. The final temperature of the system was found to be 28.4°C. Calculate the specific heat of the metal. (The heat capacity of the calorimeter is 12.4 J/°C.)
Answer: 0.52849 j /g °C
Explanation:
Given the following :
Mass of metal = 36g
Δ Temperature of metal = (28.4 - 99)°C = - 70.6°C
Mass of water = 70g
Δ in temperature of water = (28.4 - 24.0) = 4.4°C
Heat lost by metal = (heat gained by water + heat gained by calorimeter)
Quantity of heat(q) = mcΔT
Where; m = mass of object ; c = specific heat capacity of object
Heat lost by metal:
- (36 × c × - 70.6) = 2541.6c - - - - (1)
Heta gained by water and calorimeter :
(70 × 4.184 × 4.4) + (12.4 × 4.4) = 1288.672 + 54.56 = 1343.232 - - - - (2)
Equating (1) and (2)
2541.6c = 1343.232
c = 1343.232 / 2541.6
c = 0.52849 j /g °C
Balancing Chemical Reactions Worksheet A glow stick is a popular toy and safety device. To use a glow stick, you bend a small flexible plastic tube to break a small glass capsule inside, at which point the stick begins to glow. How do you think this works
Answer:
Concept of chemi-fluorescence
Explanation:
A glow stick usually consists of two chemicals in a larger plastic tube: , a base catalyst (mostly sodium salicylate), and a suitable dye (sensitizer, or fluorophor). This creates an exergonic reaction when mixed together.
When a glow stick is bent, the flurophor which is a chemical that easily re-emits light upon excitation in smaller capsules is released into the other substance, there by causing it to emit radiation/light in the uv-visible region. The brightness and longevity of the glow stick is determined by varying the concentration of these chemicals.
I hope this explanation clarifies things.
4. How much force, in g cm / s2 , is exerted by a golf ball described in problem 2 striking a tree while accelerating at 20 cm / s2 ? Show how you can solve this problem without knowing that F = m a. Explain your solution.
Answer:
Explanation:ifk
What is the [tex]K_{c}[/tex] Expression for the following reaction [tex]C_{6}H_{12}O_{6} + O_{2} \ \ - \ \ \textgreater \ 6H_{2}O+6CO_{2}[/tex] NO ABSURD ANSWERS!
Answer:
[tex]\boxed{\mathrm{view \: explanation}}[/tex]
Explanation:
This is an irreversible reaction, we cannot derive any [tex]\mathrm{K_c}[/tex] expression for it. The [tex]\mathrm{K_c}[/tex] expression can only be derived for reversible reactions and not irreversible reactions. We cannot derive the [tex]\mathrm{K_c}[/tex] expression for this reaction.
How does increasing temperature increase the number of reactions
Answer:
A
Explanation:
the increase in the temperature let's the particles to collide more so it increases the rate of reaction.
Answer:
I think the answer is option A.
Explanation:
Because when the temperature increases, the kinetic enegry increases which creates the effective collisions which lets the chemical to react.
Hope it helps..
25g ice crystals are taken in a beaker and inserted a thermo meter into it and slowly heated. Answer the following questions based on the above experiment.
a) At what temperature ice starts melting?
b) At 50 0 C is reached, what is the physical state of ice?
c) At 100 0 C is reached the boiling point of substance is not rising for some time. What is the reason for it?
d) What is the boiling point of the substance?
e) What is physical state of the substance above 100 degree C?
Answer:
a) 0°C
b) liquid
c) The energy supplied at 100°C is utilized in breaking the intermolecular forces in the liquid.
d) 100°C
e) gas
Explanation:
There are three States of matter; solid, liquid and gas. If we start heating 25g of ice in a beaker with a thermometer inserted into it, the ice will change from solid to liquid and finally to gas as the temperature increases.
At 0°C, the solid ice begins to melt and remains liquid between 0°C-100°C. This is called the liquid range of water. At 100°C, the heat supplied does not lead to further rise in temperature. The energy supplied is rather utilized in breaking the intermolecular forces in the liquid. This is known as the latent heat of vaporization. Above 100°C, the liquid is changed to vapour. Water vapour is commonly called steam.
Indicators change color when an acid and a base are mixed together. The change in color most likely indicates that a chemical change has occured. a physical change has occured. a new acid has been produced. a new base has been produced.
Answer:
a chemical change
Explanation:
a physical change is mostly identified even without indicators i.e candle wax about forming a new acid or base I guess we have to include a ph scale to ascertain since the salt can be acidic but not necessarily an acid
Answer: The answer is A, a chemical change has occurred
Explanation:
I’m just a jenious
How science classified?
any additional answer please thanks
Answer:
Scientific Classification. Classification, or taxonomy, is a system of categorizing living things. There are seven divisions in the system: (1) Kingdom; (2) Phylum or Division; (3) Class; (4) Order; (5) Family; (6) Genus; (7) Species. ... Species are identified by two names (binomial nomenclature)
Explanation:
Which of the following phrases describes valence electrons?
O A. Electrons that are part of the core of the atom
O B. Electrons that are closest to the nucleus
O C. Electrons that are farthest from the nucleus
D. Electrons identified by the period number of the element
Answer:
C
Explanation:
because valence electrons are located at the last energy level
Element Grouping Quick Check:
1. Which element has two valence electrons?
D. calcium
2.Based on its position in the periodic table, which element would have seven valence electrons?
A. Chlorine
3. Which phrase describes a valence electron?
C. An electron in the outer energy level of an atom
4. Which phrase best describes a period on the periodic table?
A. A row of elements
5. Which two elements have the same number of energy levels with electrons in them?
A. Boron and Oxygen
Hope this helps!
A climber is attached to a vertical rope that has a tension of 785 N. If the
climber has a mass of 85 kg, what is the net force on the climber?
O A. 48 N up
OB. 542 N up
O C. 700 N down
O D. 48 N down
SUBMIT
Answer:
D. 48 N down
Explanation:
Given that:
Mass of climber = 85 kg, Tension on rope = 785 N, acceleration due to gravity = 9.8 m/s²
To calculate the net force on the climber, we need to first calculate the weight of the climber. Since the climber is affected by the earth gravity, the weight of the climber is the product of his mass and the acceleration due to gravity, therefore:
Weight = mass × acceleration due to gravity = 85 kg × 9.8 m/s² = 833 N
The weight of the climber is acting downwards while tension on the rope is acting upwards, therefore:
Net force on the climber = 785 N - 833 N = - 48 N
This means that the net force on the climber is 48 N downwards
Answer:
48 N down
Explanation:
Ayepecks
Un compuesto ZO2 tiene masa molar igual a 64. La masa atómica de Z debe ser: A . 6. C. 12. E. 32. B. 10. D. 24.
Answer:
32. Opcion E
Explanation:
ZO₂ podemos entenderlo como dióxido de Z
1 mol de ZO₂ contiene 1 mol de Z y 2 moles de O₂ por lo que si la masa molar es de 64 g/mol, podemos plantear lo siguiente
Masa de Z + 2 masa de O = 64 g/mol
Sabemos que la masa del oxígeno es 16 g/mol
x + 2. 16 g/mol = 64 g/mol
x = 64 - 32 → 32 g/mol
La masa atómica coincide con la masa molar, por lo tanto la masa atomica de Z es 32.
Considerando la definición de masa molar, la respuesta correcta es la opción E: La masa atómica de Z debe ser 32.
La masa molar es la masa de un mol de una sustancia, la cual puede ser un elemento o un compuesto, esto es, es la relación entre la cantidad de sustancia y su masa.
En otras palabras, la masa molar es la cantidad de masa que una sustancia contiene en un mol.
En la tabla periódica, se puede encontrar la masa molar de los elementos, también llamada masa atómica o peso atómico.
Para calcular la masa molar de un compuesto, también llamado masa o peso molecular, se debe sumar la masa molar de los elementos del compuesto multiplicado por su cantidad en el compuesto.
Entonces, en este caso, siendo la masa molar del oxígeno (O) 16, y la masa molar del compuesto ZO₂ 64, y denominando x a la masa molar de Z, entonces la masa molar del compuesto puede expresarse como:
x + 2×16= 64
Resolviendo:
x + 32= 64
x=64 -32
x=32
Finalmente, la respuesta correcta es la opción E: La masa atómica de Z debe ser 32.
Aprenda más:
https://brainly.com/question/23183573?referrer=searchResultsTwo oxides of lead were separately reduced to metallic lead by heating in a current of
i) Mass of yellow oxide taken=3.45g
ii) Mass of brown oxide taken=1.227g
Loss in mass during reduction=16g
Show that the above data illustrate the law of multiple proportions.
Answer:
HeyA ❤
Let us consider the mass of oxygen as 1 g.
Mass of lead obtained from yellow oxide = 3.45 g – 0.24 g = 3.21 g
Mass of oxygen = 0.24 g
The mass of lead that combines with 0.24 g of oxygen = 3.21 g
Therefore, mass of lead that combines with 1 g of oxygen = 3.21/ 0.24 = 13.4 g
Mass of lead obtained from brown oxide = 1.227 g – 0.16 g = 1.067
Mass of oxygen = 0.16g
The mass of lead that combines with 0.16 g of oxygen = 1.067 g
Therefore, mass of lead that combines with 1 g of oxygen = 1.067/ 0.16 = 6.66 g
Now, ratio of masses of lead which combines with a fixed mass of oxygen = 13.4 : 6.66
= 2 :1
Thus, masses of lead which combine with the fixed mass of oxygen are in the ratio of (2:1) i.e. small whole numbers.
Hence, the law of multiple proportions is illustrated.
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