The half-life of the Uranium-235, given that 25% of it is remaining in the rock is 713 million years
How do i determine the half-life?We know that half life is the time taken for half of a substance to decay.
Thus, to obtain the half life of the Uranium-235, we shall calculate the number of half lives that has elapsed while in the rock. This can be obtained as follow:
Original amount of Uranium-235 (N₀) = 100%Amount remaining of Uranium-235 (N) = 25%Number of half-lives (n) =?2ⁿ = N₀ / N
2ⁿ = 100 / 25
2ⁿ = 4
2ⁿ = 2²
n = 2
Knowing that 2 half lives has already elapsed, we shall determine the half-life of the Uranium-235. This can be obtained as follow:
Number of half-lives (n) = 2 Age of rock (t) = 1.426 billion years Half-life (t½) = ?t = n × t½
Divide both sides by n
t½ = t / n
t½ = 1.426 / 2
t½ = 713 million years
Therefore, we can conclude that the half-life is 713 million years
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Describe these three experiments which have been used to support the atomic theory: Cathode Ray Tube, Gold Foil Experiment, and Atomic Emission Spectra.
The atomic theory developed along the experiments of the Cathode Ray Tube, Gold Foil and Atomic Emission Spectra.
What is the atomic theory?The term atomic theory has to do with the arrangement of the particles that compose the atom. Let us look at the development of the atomic theory chronologically.
Cathode Ray Tube - In the cathode ray tube, J.J Thompson was able to pass an electric discharge through the tube and a color was observed that corresponds to the gas in the tube.
Gold foil experiment - Here, thin gold foils were bombarded with alpha particles and the movement of the alpha particles were tracked.
Atomic emission spectra - Here, electrons were excited to different wavelengths and the corresponding spectra was observed.
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When sodium hydroxide reacts with sulfuric acid a solution of sodium sulfate is produced.
a.) Describe how crystals of sodium sulfate can be obtained from a solution of sodium sulfate.
When an acid and a base react, the base balances the acid, creating salt and water as a result..
2NaoH+ H2SO4----> Na2SO4 + H2O
Both sulfuric acid H2SO4 and sodium hydroxide NaOH are powerful acids and bases, respectively.
This reaction is exothermic in nature and is referred to as the neutralizing reaction (since heat is released during the reaction as there is formation of new bonds).
a). If you left your aqueous sodium sulfite solution open on the side, air oxygen would catalyze the chemical shift, the water would hydrate the new compound, and the slow evaporation of water would give you wonderful huge crystals of Na2SO4 without you having to do anything.
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Which of the following samples can be considered as a concentrated
solution of Povidone Iodine, an antiseptic for minor wounds ?
A. 3 drops of Povidone Iodine dissolved in 100 ml of water.
B. 5 drops of Povidone Iodine dissolved in 100 ml of water.
C. 10 drops of Povidone Iodine dissolved in 100 ml of water.
D. 50 drops of Povidone Iodine dissolved in 100 ml of water.
The sample that should be considered concentrated solution of Povidone Iodine is 50 drops of Povidone Iodine dissolved in 100 ml of water. That is option D
What is a concentrated solution?A concentrated solution is defined as the type of solution that contains more dissolved solute with less solvent when compared with other solutions.
A solute is defined as the part of a solution that dissolves in a solvent while the solvent is part of the solution that is the dissolving medium.
From the options listed, the most concentrated solution is the solution that contains more of the povidone iodine which is 50 drops of Povidone Iodine dissolved in 100 ml of water.
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(3) What is the chemical formula of this molecule? Η Η | | H—C-C-0-HHHWhat is the name of this molecule? Build it in the playground.
Answer:
[tex]C_{2}[/tex][tex]H_{6}[/tex]O This can be one of two componds: ethanol or dimethyl ether.
Explanation:
I'm having trouble interpreting:
Η Η | | H—C-C-0-HHH
The manner in which a chemical structure is written plays a large roll in how to interpret what compund it is. In this case we can count 2 carbons, 1 oxygen, and 6 hydrogens.
From this, we are tempted to quickly conclude and write:
[tex]C_{2}[/tex][tex]H_{6}[/tex]O
and state that this is clearly ethanol. Why would it be anything else?
Although this is a correct possible interpretation of the information, but [tex]C_{2}[/tex][tex]H_{6}[/tex]O it has at least two different structures: ethanol and dimethyl ether. See the attached diagram.
Most combination of elements can have more than 1 structure, and are therefore different compounds. Because if this, the manner in which the structure is drawn is essential to how it is interpreted. Even the formula notation has certain rules designed to help identify the compound. The attached diagram illustrates the two ways ethanol and dimethyl ether can be lav=belled: C2H5OH, which highligts the -OH group and identifies it as an alcohol. Dimethyl ether has the O atom at the end, without the H atom stuck behind it. This signals that it is incorporated somewhere else in the molecule.
What is galaxy? Do you think another galaxy contains a planet similar to Earth
Answer:
A galaxy is huge group of solar systems, planets and star's e.t.c. There is a possibility of a similar planet to Earth since the universe is massive and we haven't discovered all of it yet.
How does using the ocean as an energy resource interact in both positive and negative ways within each of Earth's spheres?
The ocean using as an energy resource interact in both positive and negative ways within each of Earth's crust as the ocean produces two types of energy, these are thermal energy from the heat of sun, and mechanical energy from the tides and waves.
For example, when ships transport oil, the waste water is occasionally dumped. It means that ships may release some amount of pollution into the ocean and air. Some of the heat which is stored in the ocean could power the entire planet.
These ocean energy sources, both thermal energy and mechanical energy are non-polluting, dependable, and highly predictable. Oceans covers more than 70% of the surface of Earth. It makes them the greatest solar collectors on the planet.
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2. Explain the significance of the discovery of gallium (mass number 68) to Mendeleev periodic table
The significance of gallium is explained below
Describe gallium.The atomic number and symbol for the chemical element gallium are 31. The discovery was discovered in 1875 by French chemist Ga. Paul-Émile Lecoq de Boisbaudran. Gallium is a similar metal to the other elements in Group 13 of the Periodic Table (aluminium, indium, and thallium).
Under normal pressure and temperature, gallium is a soft and silvery element. When it's liquid, it takes on an icy white hue. Using too much force could cause gallium to shatter conchoidally. Since its discovery in 1875, gallium has been frequently used to produce alloys with low melting points. It is also used in semiconductors as a dopant on semiconductor substrates.
In 1875, a French chemist by the name of Paul Emile Francois Lecoq de Boisbaudran made a spectroscopic discovery of a new element while studying zinc blende. The properties of this freshly discovered element matched those of the eka-aluminum, which has an atomic weight of 69, as predicted by Mendeleev. The specific gravity of the element was later determined to be 5.9, as predicted by Mendeleev. The substance was then given the name gallium by Lepoq, who so elevated Mendeleev's periodic table and supported Mendeleev's theories.
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a hydrogen atom emits a photon. you are given the wavelength of the photon. what sign will the energy of the photon be calculated as?
The energy of the photon to will be calculated by using E=hv.
Photons are fundamental subatomic particles that carry electromagnetic force — or, to put it another way, they are light particles. The energy of a photon is calculated by determining the wavelength of the photon. To do this, we need to know the frequency of the light and its speed in a vacuum.
A hydrogen atom emits a photon with a frequency of about 6.6x1014 Hz and a speed in a vacuum of 3.0x108 m/s.
The value for E = hν is:
E = hν
= Planck's Constant × Frequency × Wavelength
= hc/(2π×frequency × wavelength)
The unit of energy is given by Joules(J).
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Copper(II) oxide can be reduced by hydrogen:
CuO(s) + H2(g) → Cu(s) +H2O(g)
What mass of copper can be obtained from 15.9 g of copper(II) oxide?
Answer:
do that in calc
Explanation:
mass of cu = 63.55 ÷ 79.55 × 15.9
Help, how to solve? - The question underneath, why is it Option C (4.8*10^23 ions) and not option B (1.2*10^23 ions). How do we solve and approach the question?
Option C (4.8 × 10²³ ions) is correct not option B (1.2 × 10²³ ions) as one molecule of (NH₄)₃PO₄ contains four ions, three NH₄⁺, and one PO₄⁻³.
To calculate ions, first, we have to calculate number of molecules of (NH₄)₃PO₄ in 0.20 moles.
To calculate number of molecules, the number is moles is multiplied by Avogadro number (6 × 10²³).
So, the number of molecules of (NH₄)₃PO₄ in 0.20 moles is,
Number of molecules = 0.20 × 6 ×10²³ = 1.2 × 10²³
One molecule of (NH₄)₃PO₄ contains three ions of NH₄⁺, and one ion of PO₄⁻³. So, number of ions in 0.20 moles of (NH₄)₃PO₄ are
Number of ions = 4 × 1.2 × 10²³ =4.8 × 10²³
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Look at the two waves shown. What is the speed of each wave?
The speed of all electromagnetic waves is equal to the speed of light that is 3 × 10⁸ m/s.
What is an electromagnetic wave?An electromagnetic wave is a wave of certain wavelength of an electromagnetic radiation of the electromagnetic spectrum. There are different types of waves in the spectrum like IR, radio waves etc.
The speed of c of the wave is the product of its frequency and wavelength. The speed of all electromagnetic waves are equal to the speed of visible light.
Hence, the speed of both waves is 3 × 10⁸ m/s.
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If [H+] = 1.0 x 10-11 M, what is the pH of the solution?
Answer:
use the pH equation :
pH: -log [H+]
pH: -log 1×10^-11
pH: 11.00
the pH of the solution is 11.00 and the solution is basic.
and make sure to remember :pH does not have a value .
a solution merely has pH(11.00)
Which expression is equivalent to −3(4x + 3y)?
3y(4x − 3)
4x(−3 + 3y)
−12x + 3y
−12x − 9y
The expression equivalent to -3(4x + 3y) is -12x - 9y
The expression we have is = -3(4x+3y)
We will apply the distributive property to find the correct expression,
The distributive property-
It states that when the sum of two or more variable are multiplied by a number gives the exact similar result as when each variable is multiplied separately by the number, and the products of both are added together.
The distributive property of the addition is given as -
A(B + C) = AB + AC
The distributive property of the subtraction is given as -
A(B - C) = AB - AC
We know the expression is -3(4x + 3y)
We will apply the distributive property in the given expression
-3(4x + 3y) = -12x - 9y
Hence, the expression equivalent to -3(4x+3y) is -12x-9y
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What is the speed of a car that travels 45 miles in 45 minutes? Answer in miles per hour.
Answer:60 miles in one hour
Explanation:
Here is my question on Electron Configurations. There are 5 parts: a to e.
Answer:
too lendi to answer the question
suppose you have 350.0 ml of a 0.650 m sodium hydroxide solution. how many moles of sodium hydroxide are in the solution? type answer:
The moles of sodium hydroxide when you have 350.0 ml of a 0.650 m sodium hydroxide solution is 0.2275 moles.
According to the definition of molarity, we can draw the definition of 1M as
If 1 Mol of solute is present in 1000 mL of solution, then the solution will be called one molar ( or 1M)
Thus in the given problem 0.650 M of NaOH means,
1000 mL of solution contains 0.650 M NaOH
So, 350 mL 0.650 M NaOH solution will contain
0.650 × 350/1000 moles of NaOH.
That is equal to 0.2275 moles of NaOH.
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a certain inorganic acid has a pka of 5.2. what is its ka? enter your answer in scientific notation. be sure to round your answer to the correct number of significant figures.
The acid ionization constant of a solution is represented as Ka. The Pka is the negative logarithm of Ka value. The ka value of the acid with pka of 5.2 is 6.3 × 10⁻⁶ .
What is acid ionization constant?Acid ionization constant is the ratio of product of concentration of the ions in the acid to the molar concentration of the acid.
If and cid HA ionizes into H+ and A- then ionization constant Ka is written as follows:
Ka = [A-] [H+] / [HA]
Mathematically pka is the negative logarithm of ka value. The pka value is given 5.2 thus ka value is calculated as follows:
pka = -log (Ka)
- 5.2 = log (Ka)
Ka = antilog (5.2)
= 6.3 × 10⁻⁶.
Therefore, ka value of the acid with pka of 5.2 is 6.3 × 10⁻⁶ .
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the irreversible elementary reaction a → b takes place in the gas phase of an isothermal, isobaric pfr. reactant a and a diluent c are fed in equimolar ratio. if the molar feed rate of c is doubled and the conversion is kept constant, by how much does the reactor size change?
The change in the reactor size of the Plug flow reactor for gas phase reactions is by a factor of 1.5 in the volume.
Chemical engineers typically utilize a model known as the plug flow reactor model (PFR, also known as continuous tubular reactor, CTR) to explain chemical reactions in continuous, flowing systems with cylindrical shape. Since it has no moving components, the tubular reactor (also known as the plug flow reactor [PFR]) is one of the flow reactors that typically achieves the maximum conversion per reactor capacity.
The single-step chemical reactions that take place in the gas phase are the easiest to understand. Both intramolecular and intermolecular reactions occur in the gas phase.
The performance equation of Plug flow reactor (PFR):
[tex]\frac{V_P}{F_A_0} = \int\limits^{X_A}_0 \frac{dX_A}{(-r_A)}[/tex]
where,
[tex]V_P[/tex] – reactor volume in [tex]m^3[/tex]
[tex]F_{A0}[/tex] – molar feed rate (C + A in feed)
Let [tex]F_{A0}[/tex] = 100 mol/s
i.e.,
[tex](F_{A0})_A[/tex] = 50 mol/s
[tex](F_{A0})_C[/tex] = 50 mol/s
So,
[tex]{V_P} = 100 \int\limits^{X_A}_0 \frac{dX_A}{(-r_A)}[/tex]
When [tex]F_{C0}^'[/tex] = 2[tex]F_{C0}[/tex] (doubled) with same conversion [tex]X_A[/tex]
Then,
[tex]{V_P^'} = 50 + 100 \int\limits^{X_A}_0 \frac{dX_A}{(-r_A)}[/tex]
Therefore,
Volume, [tex]V_P^'[/tex] = 150 / 100 = 1.5
Result:
The volume of the plug flow reactor changes by a factor of 1.5
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In a parallel circuit with identical light bulbs, which of these is true?
A
A battery is not the source of voltage.
B
There is only one resistor, such as a light bulb.
C
The circuit is left open so that current cannot flow.
D
Adding more identical light bulbs will not change their brightness.
In a parallel circuit with identical light bulbs, the true statement is option D Adding more identical light bulbs will not change their brightness.
Two bulbs in a simple parallel circuit every experience the overall voltage of the battery. that is why the bulbs in the parallel circuit might be brighter than the ones within the series circuit. some other gain to the parallel circuit is that if one loop is disconnected, then the other stays powered.
While batteries are connected in parallel, the voltage remains the same, but the contemporary which could float in the circuit will increase. when bulbs have equal power, then their resistance is likewise the same. while the 2d bulb connected in parallel to the first bulb is switched on, the effective resistance of the circuit turns into half of, and the present-day circuit becomes double. due to it, this double modern-day divides itself equally into bulbs.
The voltage across every resistor inside a parallel aggregate is precisely equal however the currents flowing through them are not the same as that is determined by their resistance fee and Ohms regulation.
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What scientific principle do bulletproof vests worn by law enforcement officers best illustrate when they protect personnel from impact injury in the line of duty?
Answer:
Ballistic vests use layers of very strong fibers to "catch" and deform a bullet, mushrooming it into a dish shape, and spreading its force over a larger portion of the vest fiber. The vest absorbs the energy from the deforming bullet, bringing it to a stop before it can completely penetrate the textile matrix.
In your own words, describe the relationship between temperature and how molecules move.
This long unit of measurement can be used to measure great distances. It *
is equal to 1000 meters.
Omillimeter
O centimeter
O meter
O kilometer
Odecimeter
A river flows at a rate of 57.3m/sec, what is the rate when it is converted to km/day? Please answer fast!!!
What is the volume of 2.00 moles of an unknown gas at STP?
O2.00 L
0 11.2L
0 44.8L
O 22.4L
What is the lithosphere? ) (25 pts)
Why are race cars and bicycles made of lightweight materials?
"The planets revolve around the sun in an elliptical pattern because of the respective gravitational forces that
interact between the sun and the other planets." This statement is an example of a:
O
fact.
O
law.
O
theory.
O
hypothesis.
The statement planets revolve around the sun in an elliptical pattern because of the respective gravitational forces that interact between the sun and the other planets is an example of a theory (Option 3).
What is a scientific theory?A scientific theory is a statement well-sustained by scientific evidence, which is empirical because it is testable, i.e. we can confirm or reject it by experimentation, and predictable
Therefore, with this information, we can conclude that a scientific theory is based on empirical evidence that we can test and confirm by experimental or observational procedures.
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What mass of HCI is needed to
generate 45.2 g of AICI3?
2AI + 6HCI → 2AlCl3 + 3H₂
AICI3: 133.33 g/mol
HCI: 36.46 g/mol
Answer:
37.1g of HCl
Explanation:
rate as brainliest
Write the electron configuration (1s², 2s²,...) for the following:
Hydrogen
2
Fluorine
Boron - 1s²2s²2p¹
3 Aluminum
Draw the electron configuration with the correct atomic orbitals for the following:
4 Sodium
6
5 Sulfur
Boron-
Argon
15². 25
2p
that is for hydrogen, fluorine and aluminium
If a substance conducts electricity when dissolved in water, turns litmus from blue to red, and tastes sour, would you expect it to be acidic, basic, or neutral? Justify your answer.
Answer:
The substance is acidic.
Explanation:
When a substance is able to dissolve in water, it means that it is ionic. This just means that the polarity of the water and the polarity of the substance will attract each other to their positive and negative ends respectively. (Positive attracts negative and negative attracts positive).
Litmus paper that is blue and then turns red when introduced to a substance, is known to be acidic.
The opposite can be said when red litmus paper turns blue when introduced to a substance; this means the substance is basic.
Also, if it is sour, then that means it is acidic! Some examples of sour things that are acidic are soft drinks, apples and lemons/limes.