Answer:
option A is the most supported hypothesis by astronomers
How many atoms of lead are present in 78.40 grams of lead?
mole = 78.40/207.2
= 0.379 mol
1 mol = 6.02 × 10^23 atoms
0.379 mol = X
X = 0.379/1 × 6.02 × 10^23
= 6.296 × 10^-25 atoms
What is the empirical formula for a compound that is comprised of 54.0% sodium, 8.50% boron, and 37.5% oxygen by mass
Answer:
Sodium metaborate: sodium+boron+oxygen= NaBO 2.
The formula can be written also as Na 2O·B
Explanation:
Which transition could represent an atom that emits a photon with 10.2 eVeV of energy?
Solve for x if 1/2x-3 + 5x/2x+6 =2
Answer:
by which method do you need
Given:
[tex]\to \frac{1}{2x-3} + \frac{5x}{2x+6} =2[/tex]
To find:
x=?
Solution:
[tex]\to \frac{1}{2x-3} + \frac{5x}{2x+6} =2 \\\\[/tex]
Taking lcm:
[tex]\to \frac{2x+6 +5x(2x-3)}{(2x-3)(2x+6)} =2\\\\\to \frac{2x+6 +10x^2- 15x}{(4x^2+ 12x-6x-18)} =2\\\\\to \frac{10x^2- 13x+6}{4x^2+ 6x-18} =2\\\\[/tex]
[tex]\to 10x^2- 13x+6 = 2(4x^2+ 6x-18)\\\\\to 10x^2- 13x+6 = 8x^2+ 12x-36\\\\\to 10x^2- 13x+6 - 8x^2- 12x +36=0\\\\\to 2x^2-25x+42=0\\\\[/tex]
compare the value with the [tex]ax^2+bx+c=0[/tex]:
[tex]\to a=2\\\\\to b= -25\\\\\to c=42\\\\[/tex]
Using formula:
[tex]\to \bold{x=\frac{-b \pm \sqrt{b^2-4ac}}{2a}}[/tex]
[tex]\bold{=\frac{- (-25) \pm \sqrt{(-25)^2-4\times 2 \times 42}}{2 \times 2}}\\\\ \bold{=\frac{25 \pm \sqrt{ 625 - 336}}{4}}\\\\ \bold{=\frac{25 \pm \sqrt{289}}{4}}\\\\ \bold{=\frac{25 \pm 17 }{4}}\\\\ \bold{=(\frac{8}{4} , \frac{42}{4})}\\\\ \bold{=( 2 , \frac{21}{2})}\\\\[/tex]
Therefore, the final answer is "[tex]\bold{(2, \frac{21}{2})}[/tex]".
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Which functional group is within the compound shown below?
The model below shows the equation that represents how hydrogen and oxygen combine to form water. In this chemical reaction, the reactants
are hydrogen gas and oxygen gas.
2H2 + O2 + 2H2O
True
False
Answer:
true
Explanation:
because they are balance
a fisherman in a boat is drinking a of hot coffee. the large lake below his boat is full of cold water. which statement is an accurate comparison of the lake water and the coffee?
Answer:
see below
Explanation:
The lake will have more total thermal energy but the particles in the coffee will be moving faster.
A comparison of hot coffee and cold lake is, the heat from the coffee will be absorbed by the cold lake through convection method of heat transfer.
Conservation of energy
The principle of conservation of energy states that the total energy of an isolated system is always conserved.
Heat lost by the hot coffee = Heat absorbed by the cold lake
Heat transfer processHeat from the coffee will be absorbed by the cold lake through convection method of heat transfer.
Thus, a comparison of hot coffee and cold lake is, the heat from the coffee will be absorbed by the cold lake through convection method of heat transfer.
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flowering plants are called
flowering plants are called?
Answer:-Angiosperms
Explanation:-Angiosperms are plants that bloom and bear fruit. The word angiosperm is derived from two Greek words, Angeion and Sperma . Angeion means "vessel" and sperma means "seed".
What is the stock name for chromic ion
Answer:
Chromium(III)
PubChem CID 27668
Structure Find Similar Structures
Chemical Safety Laboratory Chemical Safety Summary (LCSS) Datasheet
Molecular Formula Cr+3
Synonyms Chromium(III) Chromic ion chromium(3+) CHROMIUM (III) Chromic cation More
What is the wavelength, in nanometers, of light with a frequency of 1.97x10^15 Hz?
a) 1.52 nm
b) 1.52x10^-7 nm
c) 152 nm
d) 15.2 nm
If the vapor pressure of water at 20.0 o C is 17.535 torr, and the atmospheric pressure measured by a barometer was 757.3 torr, what is the partial pressure of H2 in the gas mixture in a buret
Answer:
f the vapor pressure of water at 20.0 o C is 17.535 torr, and the atmospheric pressure measured by a barometer was 757.3 torr, what is the partial pressure of H2 in the gas mixture
Partial pressure of H2 in gas mixture is :
739.765 torr .
Explain total pressure?The overall pressure ptot is the total of all pressures in a reference system. This pressure, according to Bernoulli (see Fluid mechanics), consists of the static pressure p, the dynamic pressure pdyn, and the geodetic component ( g z) that exists in a fluid along a stream line in a frictionless flow.The total pressure of a gas mixture is the sum of its component gases' partial pressures: Ptot = ∑Pi = P1 + P2 + P3... ntot = total number of moles in the gas mixture (the sum of all ni).Total pressure of mixture =
Partial of hydrogen + Partial pressure of oxygen
Partial of Hydrogen = Total pressure - partial pressure of oxygen
Here total pressure = 757.3 torr
Partial pressure of oxygen = 17 . 535 torr
Total pressure = 757 . 3 - 17 . 533
= 739.765 torr.
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need answer asap ..
-20 points! asap please ..
Answer:
[tex][tex]\purple{\rule{45pt}{7pt}}\purple{\rule{45pt}{999999pt}}[tex][/tex]
Explanation:
[tex][tex]\purple{\rule{45pt}{7pt}}\purple{\rule{45pt}{999999pt}}[tex][/tex]
A substance has a molar heat of combustion of -810.4 kj/mol. when 0.285 mol of the substance is burned in a calorimeter containing 8.60 kg of water, the increase in water temperature is:
Answer:
6.42 °C
Explanation:
Q = mcΔT
Q = energy gain/release (J)
m = mass (kg)
c = specific heat capacity (J/°C/kg)
ΔT = change in temperature (°C)
Qs = n(ΔH°c)
Qs = energy gained/released from substance (kJ)
n = moles (mol)
ΔH°c = molar heat of combustion (kJ/mol)
m = 8.60
n = 0.285
ΔH°c = -810.4
c (of water) = 4184
Qs = 0.285(-810.4)
Qs = -230.964 (or -230964 J)
Q = 230964
230964 = (8.60)(4184)ΔT
230964 = 35982.4(ΔT)
ΔT = 6.4188... °C → 6.42 °C
For an imaginary closed economy, T = $5,000; S = $11,000; C = $48,000; and the government is running a budget surplus of $1,000. Then
Based on the information given, the private savings will be $10000 and the gross domestic product is $63000.
From the information given, he following can be gotten:
T = $5,000S = $11,000C = $48,000Budget surplus = $1000Since, S = Y - C - G
11000 = Y - 48000 - G
Y - G = 48000 + 11000
Y - G = 59000
Budget surplus = T - G = 1000
5000 - G = 1000
G = 5000 - 1000 = 4000
The GDP will be:
Y - G = 59000
Y - 4000 = 59000
Y = 59000 + 4000 = 63000
Private savings = Y - T - C
Private savings = 63000 - 5000 - 48000
Private savings = 10000
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Giúp mình 2 câu này với ạ
1, Pha 500ml dung dịch HCl 10% (w/v) từ dung dịch 37% (w/w) d=1.19 g/ml
2, Cách pha như thế nào để nhận được 200g dung dịch HCl 25% (w/w) từ dung dịch HCL 37% (d=1.19 g/ml)
Answer:it is wrong answer
Explanation:estro man
Industrial chemists have to understand the chemistry of oxides.
For example, silicon dioxide is used in glass making and carbon monoxide is used in the
extraction of iron from iron ore.
(i) Explain how burning carbon in air can lead to the formation of carbon monoxide.
(2)
(ii) Write the balanced equation for the reaction between silicon and oxygen.
(2)
Answer:
carbon monoxide can be formed due to incomplete combustion of carbon due to insufficient oxygen supply
2C+O2___2CO
Si+O2____SiO2
Which type of energy uses the photoelectric effect?
Biomass
Solar
Geothermal
Wind
Answer:
My lovely people the answer is SOLAR
Explanation:
i just know
The type of energy that uses the photoelectric effect is solar energy. Therefore, the correct option is option B.
When light strikes a material surface, the photoelectric effect takes place, which results in the emission of electrons. Albert Einstein made this intriguing discovery in 1905, and it was essential in the development of quantum physics and our comprehension of the nature of light. The fundamental principle underlying the photoelectric effect is that light is made up of small energy packets known as photons. A photon's energy can be transferred to an electron in a solid or atom when it interacts with those structures. The type of energy that uses the photoelectric effect is solar energy.
Therefore, the correct option is option B.
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An hibernating bear accumulates 25 kg of a triglyceride (846 g/mol) comprising the following fatty acids: C16, C17 and C18∆9. How many grams of β-hydroxybutyrate (104 g/mol) can the bear produce from this triglyceride during its hibernation?
The quantity of β-hydroxybutyrate the bear can produce
during hibernation is 3,073.30grams.
Hibernation is defined as the period of less activity by animals to conserve energy to survive coarse weather conditions.
A typical example of an animal that hibernates is the bear.
From the question, a bear is able to accumulate 25kg (25000grams) of triglyceride.
To calculate quantity of β-hydroxybutyrate that would be produced from 25kg triglyceride;
846g of triglyceride = 104grams of β-hydroxybutyrate
25000g of triglyceride = x grams
(Cross multiple to solve for x grams)
X = 104 × 25000/846
[tex]x = \frac{104 \times 25000}{846} [/tex]
[tex]x = \frac{2600000}{846} [/tex]
[tex]x = 3073.30grams[/tex]
Therefore, the quantity of β-hydroxybutyrate the bear can produce during hibernation is 3,073.30grams.
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2CH3CHO+O2=> 2CH3COOH
Answer:
2CH3CHO + O2 → 2CH3COOH
Is it correct ?!???!);$);
Answer:
None of the above
Explanation:
process of elimination i guess, also delta E measures the amount of change in visual perception of two colors, so it probably wont mean w (work).
then again i may be wrong-
Would you expect a Boron (B) atom with atomic mass = 9.999 to be stable?
The balance of forces allows to find the result for the question if the isotope of boron 9.99 una is stable:
The boron isotope of mass 9.99 uma is unstable because the repulsive force increases.The stability of atomic nuclei depends on the balance the force is electrostatic repulsion between the protons and the strong interaction of attraction.
One way to achieve this balance is to increase the separation of the protons with uncharged particles between them, the neutral ones, the strong interaction is of the same magnitude for protons and neutrons, therefore the repulsion is decreased and the strong attraction interaction is maintained. .
In the case of Boron, which has 5 protons, the stable structures have more atomistic 10 and 11 una, which is why it has 5 and 6 neutrons each. Therefore each proton has a neutrons next to it and in the other case a proton at the end has two neutrons, this causes the distance between the protons to increase, decreasing the electrostatic repulsion.
It indicates that we have a Boron nucleus of mass 9.999. The number of protons must remain fixed, therefore there are only 4 neutrons.
Consequently, some of the protons does not have a neutron next to it and can approach the other proton, therefore the electrostatic repulsion increases and the stability of the atom decreases.
In conclusion, using the balance of Forces we can find the result for the question if the isotope of boron 9.99 una is stable:
The boron isotope of mass 9.99 amu is unstable because the repulsive force increases.Learn more about nuclear stability here: https://brainly.com/question/897383
periodicity in chemical properties is based on atomic structure." explain.
Answer:
Periodicity is caused by regular and predictable variations in element atomic structure. ... The rows in the periodic table (the periods) reflect the filling of electrons shells around the nucleus, so when a new row begins, the elements stack on top of each other with similar please help me rank up
Periodicity means the repeating trends in properties of elements in a regular interval. Precocity in chemical properties depends on the atomic structure because, the size, number of electrons, etc affects their reactivity.
What is periodicity?Periodicity is the repetition in in trends in properties after a regular interval. In periodic table, all the elements are classified into different groups and periods.
Groups are vertical columns containing elements of same number of valence electrons and similar chemical and physical properties. Periods are horizontal rows where elements are arranges in the increasing order of atomic number.
Along a period the atomic size decreases, ionization energy and electronegativity increases. But down a group just the reverse for this happens.
In a chemical reaction only valence electrons are participating and the size and number of valence electrons etc affects the chemical reactivity of elements. That's why it is said like periodicity in chemical properties is based on the atomic structure.
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What physical property does salt have when it is dissolved in water?
And
What type of mixture is salt water?
Which of the following expresses the value 300,000,000 in correct scientific notation?
Group of answer choices
3 x 108
0.3 x 10-9
3 x 10-8
0.3 x 109
Answer:
3 x 10^8
Explanation:
If 16800 J of energy are added to 4200g of water, what will the change in temperature (delta T) of the water be? Specific heat of water is 4.184 J/gºC *
Answer:
okkkkkkkkkkkkkkkkkkkkkkkkkkk
I want a pharmacist technician to help me with a question please
Consider a 0.241 M aqueous solution of sodium hydroxide, NaOH.
A. How many grams of NaOH are dissolved in 24.43 mL?
B. How many individual hydroxide ions (OH-) are found in 24.43 mL?
C. How many moles of sulfuric acid, H2SO4, are neutralized by 24.43 mL of 0.241 M NaOH(aq)?
Answer:
a. 0.2355052g
Explanation:
a)
1000ml of NaOH contain 0.241moles
24.43ml of NaOH contain (24.43*0.241)/1000 moles
= 0.00588763moles
Relative Molecular Mass of NaOH
= 1*23 + 1*16 + 1*1
= 40
1mole of NaOH weighs 40g
0.00588763moles weigh (0.00588763*40) g
= 0.2355052g
B)
NaOH -> Na+ + -OH
1 mole of NaOH dissociates to form 1 mole of -OH ions
1 mole of a substance contains 6.02*10^23 particles(atoms)
= 0.00588763 * 6.02 *10^23
= ______ions
What is important about the properties of a substance that has undergone a chemical
change?
The substances created during chemical reactions, on the other hand, do not simply revert to their initial state. The most essential thing to remember is that the makeup of a material does not change when it undergoes a physical change, but it does change when it undergoes a chemical change.
Answer:
the most important thing for you to remember is that in a physical change composition of a substance does not change and in a chemical change the composition of a substance does change
How do ionic and molecular compounds behave in water?
Answer:
When ionic compounds dissolve in water they go through a process called dissociation, splitting into the ions that make them up. However, when you place covalent compounds in water, they typically do not dissolve but form a layer on top of the water.
When thinking about genetic engineering in agriculture, which type of issue has the most direct consequences? economical issues political issues social issues environmental issues
Explanation:
It is claimed that the increases in crop productivity brought about by genetic engineering can help relieve problems faced by farmers by decreasing the losses caused by pests, disease, weeds, and other stressors (Guerinot 2000).