Answer:
D. One or two letters are used to represent the name of each element.
Explanation:
The name of each element in the periodic table is symbolized by one or two letters.
There different ways of achieving this. Sometimes;
the first letter of the name of the element is used to represent it for example, hydrogen = H the first two letters are sometimes used, for example Calcium Cathe Latin name is also used for example Gold is Aurum and is represented as Au.These are some of the ways of symbolizing the name of each element
write five characteristics of good government?
Explanation:
giving equal opportunity,making good governance, maintaining peace and harmony among people, other try to write by your self
Need help now
Approximate half-life
Radon-222 = 4 days
A sample contains 18mg of radon-222. You estimate that this is 0.01% of the original isotope. How many half-lives have passed?
13 half-lives have passed
Further explanationGeneral formulas used in decay:
[tex]\large{\boxed{\bold{N_t=N_0(\dfrac{1}{2})^{t/t\frac{1}{2} }}}[/tex]
T = duration of decay
t 1/2 = half-life
N₀ = the number of initial radioactive atoms
Nt = the number of radioactive atoms left after decaying during T time
t1/2 = 4 days
Nt=18 mg (0.01% of the original isotope)
18 mg (Nt) = 0.01% No
No = the original isotope :
[tex]\tt No=\dfrac{100}{0.01}\times 18~mg=180,000[/tex]
The duration of decay (T) :
[tex]\tt \dfrac{Nt}{No}=\dfrac{1}{2}^{T/4}\rightarrow Nt=0.01\%No[/tex]
[tex]\tt 0.01\%=\dfrac{1}{2}^{T/4}\\\\10^{-4}=\dfrac{1}{2}^{T/4}\\\\(\dfrac{1}{2})^{13}=\dfrac{1}{2}^{T/4}\\\\13=T/4\rightarrow T=52~days[/tex]
Half-lives passed :
[tex]\tt \dfrac{52}{4}=13~half-lives[/tex]
Explore: Find an example of each of the following in the Gizmo:
A.
An example of no chemical reaction occurring:
B.
A reaction that produces an acid:
C.
A reaction that produces a base:
D.
A reaction that uses a catalyst:
Answer:
B
Explanation:
Which of these correctly describes the energy that makes the carousel turn
Answer:
F
Explanation:
A carousel can be made to rotate using different sources of energy. One may decide to use electric energy, manual effort, water energy or heat energy as in a candle carousel.
When the candle is lit, heat energy is supplied and warm air rises heating up the air near the carousel eventually causing it to start rotating.
Hence heat from the candle leads to a current of warm air that rises up, causing the carousel to start rotating.
Which of the following provides evidence for past tectonic plate motions?
A. Matching rock type and rock formations can show the way the continents were once attached.
B.Glacial evidence has been found in areas where glaciers could not exist if the continents were in their current location.
C.Ancient life forms preserved as fossils can tell us what organisms existed and where they were. Matching the fossils can show that land masses were once connected.
D. All of the above.
Answer:
D
Explanation:
If there are 2 of the same rocks on two continents, that shows that they were once merged. If there is glacial existence in places where glaciers would’ve melted (Like Africa has glacial existence from Antarctica ) this shows that continents were once merged. If life forms preserved as fossils were matched on 2 different continents this shows that all the continents were once merged.
Answer:
so i am doing this and i need help what did u get for number 1
Explanation:
its the first question
Can someone please help me with my science research I kind of need help in a few things that I listed, I’m currently working on this element which is called Curium if anyone can help me out please do, thanks. Anyway here’s the questions:
Where can it be found?
What is its importance? What are its uses?
Answer:
For your first question, Curium does not occur naturally on Earth, meaning that it is not produced naturally on Earth. However, it can be formed in nuclear reactors.
For your second question, Curium has been used to provide power to electrical equipment used on space missions, but doesn't seem to be that important overall.
Explanation:
Hope this helped!
How many ions are in
1.50 grams of Na+
Answer:Multiple the moles of Na2 SO4 that you found just
Explanation:
Ions are formed by gaining and donating the valence electrons from the outer shells. Sodium has an extra electron and forms cations. In 1.5 grams of Na⁺, there are 0.0652 moles ions.
What are cations?Cations are said to be the ions that are formed by donating electrons from their valence shell. They tend to donate their electrons to form ionic bonds with another atom that accepts the electrons.
The mass and the molar mass of the cation can be used to calculate the number of moles contained in the atom or the ion.
Given,
Mass of sodium ions = 1.50 grams
The molar mass of sodium ions = 22.98 amu
The number of moles of sodium cation is calculated as:
Moles (n) = mass ÷ molar mass
n = 1.50 ÷ 22.98
= 0.0652 moles
Therefore, 0.0652 moles are present in 1.50 grams of sodium ions.
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Calculate the pH for each H+ concentration.
[H+] = 1 x 10-8 M
pH =
---
[H+] = 0.001 M
pH
[H+] = 1 x 10-12 M
pH =
Answer:
The answer of 1×10 -8 is 2
(3.5x10^5)x(4x10^-3)=exponent form
Answer:
1.4 x 10³
Explanation:
Given:
(3.5 x 10⁵)x(4 x 10⁻³)
Find:
Exponent form
Computation:
⇒ (3.5 x 10⁵)x(4 x 10⁻³)
⇒ 3.5 x 4 x 10²
⇒ 14 x 10²
1.4 x 10³
A sample of nitrogen gas is in a 65.0-L automobile air bag and has a pressure of 745 mm Hg. What is the pressure of this sample of gas at the same temperature if it is placed into a 25.0-L bag
Answer:
the pressure = 1937mmhg using standered unit of volume
Please please please please please help I need to get this done please
Answer:
atoms
Explanation:
atoms combines to form compound
lewis structure for hypochlorus acid
AP Chemistry
25.5 g of methane burns in the combustion reaction below. How much water is produced in this reaction? CH4 + 202 -- CO2 + 2H20
A. 22.69
B. 57.39
C. 510g
D. 3.18 9
Answer:
B
Explanation:
CH4 + 2 O2 → CO2 + 2 H20
12 + I X 4 → → 2 ( I X2 + 16 )
16 → → 36
25, 5 → → ?
amount of H2O = 36 X 25,5 / 16 = 57. 39
One mole or 16 g of methane gas reacts with excess oxygen to give 2 moles or 36 g of water. Then, the mass of water produced from 25.5 g of methane is 57.3 g.
What is combustion?Combustion is the reaction of a gas with the atmospheric oxygen producing water and carbon dioxide. The hydrocarbon gases such as methane, ethane etc easily undergo combustion reaction.
As per the given balanced reaction, one mole of methane gas CH4 produces two moles of water.
molar mass of methane = 16 g/mol
molar mass of water = 18 g/mol
mass of 2 moles of water = 36 g.
Hence, 16 g methane gas produce 36 g of water.
The mass of water produced from 25.5 grams of methane gas is then calculated as follows:
mass of water = 25.5 × 36 / 16 = 57.3 g.
Therefore, 57.3 g of water is produced in this reaction from 25.5 g of methane.
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neon, a monatomic gas, that starts out at conditions of standard temperature and pressure (273.15 K, 105 Pa). Alice heats the gas at constant volume until its pressure is doubled, then Bob further heats the gas at constant pressure until its volume is doubled. If Alice and Bob assume that neon behaves as an ideal gas, then how much heat have they added to the gas for the entire process.
Answer:
819.45 K
Explanation:
Use the Ideal Gas Law to make sense of this problem, PV = nRT. From this equation, we know that pressure is directly proportional to temperature and that volume is also directly proportional to temperature. Therefore, doubling the temperature would double the pressure, and doubling the temperature would also double the volume. In the described scenario, the temperature is doubled twice, so the temperature is quadrupled (i.e. three times its original amount has been added).
The initial temperature was 273.15 K. Multiply this by 3 to get your answer of 819.45 K.
even about the food chain is correct?
Answer:
its C, because the cocunut tree gets energy from the sun and makes it into cocunut that is true
Explanation:
its C, because the cocunut tree gets energy from the sun and makes it into cocunut that is true
The largest Alkali metal is ?
Answer:
cesium is the largest alkali metal.
Explanation:
Answer:
Cesium
Explanation:
Cesium is the largest atom among alkali metal.
I need help who actually helps will get brailiest
Answer:
1. Pollution caused the bark to become darker.
2. The light-colored peppered moth had a higher chance of survival
3. The dark-colored peppered moth had a higher chance of survival
4. During the Industrial Revolution, the barks of trees got darks, causing the moths to be seen easily on a dark background. Now predators were more likely to eat the lighter cloured moths as they were easier to find. Since fewer light-colored moths were surviving, there was a smaller likelihood of light moths surviving long enough to reproduce. Since there were fewer light-colored moths, the dark-colored moths had less competition and were able to reproduce quickly.
5. Sunny, warm place: I live in a place with lots of light and sunshine, so it would be easier for light moths to blend in with their environment long enough to reproduce and thrive.
Dark, rainy Place: I live in a place with little light and sunshine, so it would be easier for dark moths to blend in with their environment long enough to reproduce and thrive.
Explanation:
2.55 gram of an alloy of silver and zinc on treatment with excess dilute hydrochloric acid gave 170 CC Of
hydrogen gas of STD. If silver remained unsolved calculate the percentage Composition of the alloy .
( Alamic masses of Zn: 65, H:1)
The percentage composition of the alloy : 19.35% Zn, 80.65%Ag
Further explanationGiven
2.55 gram of an alloy
170 cc (170 ml=0.17 L) of Hydrogen gas(H₂)
Ar Zn = 65. H=1
Required
The percentage composition
Solution
Silver remained unsolved⇒no reaction
Hydrogen gas from reaction of Zn
Zn+2HCl⇒ZnCl₂ + H₂
mol H₂ at STP (STP⇒1 mol = 22.4 L) :
[tex]\tt \dfrac{0.17}{22.4}=0.00759~moles[/tex]
From equation, mol ratio Zn : H₂ = 1 : 1, so mol H₂ = 0.00759
Mass Zn :
[tex]\tt mass=mol\times Ar\\\\mass=0.00759\times 65\\\\mass=0.49335~g[/tex]
Mass Silver :
[tex]\tt 2.55-0.49335=2.05665~g[/tex]
Percent composition :
Zn[tex]\tt \dfrac{0.49335}{2.55}\times 100\%=19.35\%[/tex]
Ag[tex]\tt \dfrac{2.05665}{2.55}\times 100\%=80.65\%[/tex]
Salt is poured from a container at 10 cm³ s-¹ and it formed a conical pile whose height at any time is 1/5 the radius of the above. At what rate is the height of the cone increasing when the height is 2 cm form the base of the cone?
Answer:
[tex]\displaystyle \frac{dh}{dt} = \frac{1}{10 \pi}[/tex]
Explanation:
Volume of a cone:
[tex]\displaystyle V=\frac{1}{3} \pi r^2 h[/tex]We have [tex]\displaystyle \frac{dV}{dt} = \frac{10 \ cm^3}{sec}[/tex] and we want to find [tex]\displaystyle \frac{dh}{dt} \Biggr | _{h\ =\ 6}= \ ?[/tex] when the height is 2 cm.
We can see in our equation for the volume of a cone that we have three variables: V, r, and h.
Since we only have dV/dt and dh/dt, we can rewrite the equation in terms of h only.
We are given that the height of the cone is 1/5 the radius at any given time, 1/5r, so we can write this as r = 5h.
Plug this value for r into the volume formula:
[tex]\displaystyle V =\frac{1}{3} \pi (5h)^2 h[/tex] [tex]\displaystyle V =\frac{1}{3} \pi \ 25h^3[/tex]Differentiate this equation with respect to time t.
[tex]\displaystyle \frac{dV}{dt} =\frac{25}{3} \pi \ 3h^2 \ \frac{dh}{dt}[/tex] [tex]\displaystyle \frac{dV}{dt} =25 \pi h^2 \ \frac{dh}{dt}[/tex]Plug known values into the equation and solve for dh/dt.
[tex]\displaystyle 10 = 25 \pi (2)^2 \ \frac{dh}{dt}[/tex] [tex]\displaystyle 10 = 100 \pi \ \frac{dh}{dt}[/tex]Divide both sides by 100π to solve for dh/dt.
[tex]\displaystyle \frac{10}{100 \pi} = \frac{dh}{dt}[/tex] [tex]\displaystyle \frac{dh}{dt} = \frac{1}{10 \pi}[/tex]The height of the cone is increasing at a rate of 1/10π cm per second.
compare the amount of heat required to vaporize 200 gram sample of h2o at its boiling point to the amount of heat required to melt 200 gram sample of h2o at its melting point
Answer:
The enthalpy of vaporization of H2O is higher than the enthalpy of fusion of H2O, therefore vaporizing the same mass of H2O would require more heat/energy than melting the same mass of H2O.
hope it helps!
please help me i will give brain list tap the question
Answer:
molecular formulas of the hydrocarbons
Answer:
coh3 and xxxxxxxxxxxxx
What is the molarity of a 4.447 L solution
that is made from 13.53 g of NaCl?
Answer in units of M.
Answer:52M
Explanation:
use S= 1000w/ MV
Here, s= molarity
w= the amount of NaCl
M= the atomic mass of NaCl
V= the volume of solution
what are the functional groups in tramadol
Answer:
1. ether group R-O-R
2. benzene ring
3. 3°- alcohol
4.3°- amine group N attached to 3 groups rather than H
Between which two objects is gravitational attraction the greatest?
between the penny and the small pot
between the book and the cereal box
between the small pot and the book
between the paper clip and the penny
Answer:
Between the small pot and the book
Explanation:
Since gravitational force is influenced by the mass of an object, the higher the mass of two objects, the stronger the gravitational force.
Thus, the force between the pot and the book is strongest, since the two have the highest mass.
Have a nice day!
which of the following turns blue with a universal indicator (Litmus paper)
1. all
2. salt
3. base
3. acid
base
This is the answer
PLS HELP WILL GIVE BRAINLYEST What happens when the magnet is removed from the coil in a circuit?
a.
The current stops
c.
The voltage decreases
b.
The current changes direction
d.
Power output increases
Answer:
b
Explanation:
g 30.0 mL of a buffer is made by mixing 20.0 mL of 0.10 M HNO2 and 10.0 mL of 0.10 M NaOH solution. What is the pH of this buffer after 0.04 mL of 10.0 M hydrochloric acid are added to it
Answer:
pH = 2.98
Explanation:
pKa of HNO2 is 3.35
HNO2 reacts with NaOH as follows:
HNO2 + NaOH → NaNO2 + H2O
Where moles of NaOH added are equal to NaNO2 produced
And initial moles of HNO2 - Moles NaOH = Moles HNO2
Initial moles HNO2:
0.0200L * (0.10mol/L) = 0.00200moles HNO2
Moles NaOH = Moles NaNO2:
0.0100L * (0.10mol/L) = 0.00100 moles NaOH = Moles NaNO2
Moles HNO2:
0.00200moles - 0.00100moles = 0.00100 moles HNO2
Then, the added HCl reacts with NaNO2 producing HNO2:
HCl + NaNO2 → HNO2 + NaCl
Where moles added of HCl are moles of HNO2 produced and initial moles of NaNO2 - moles of HCl = Moles NaNO2
Moles HCl:
4x10⁻⁵L * (10.0mol / L) = 0.00040moles HCl = Moles of HNO2 produced
Moles HNO2:
0.00100moles + 0.0004moles = 0.0014moles HNO2
Moles NaNO2:
0.00100moles - 0.0004moles = 0.0006moles NaNO2
With these moles and H-H equation we can solve for the pH of the buffer:
pH = pKa + log [NaNO2] / [HNO2]
Where pH is pH of the buffer
pKa is pKa of HNO2: 3.35
[] are moles of each species:
Replacing:
pH = 3.35 + log [0.0006moles NaNO2] / [0.0014moles HNO2]
pH = 2.98
1. The gases SO2, O2 and SO3 are allowed to reach equilibrium at a constant temperature. The equilibrium constant for the reaction
2SO2(g) + O2(g) -> 2S03(g)
is 1.6 x 104 atm-1
a) Calculate the value of Kp for the reaction
SO2(g) + ½O2(g) -> SO3(g)
(b) The equilibrium constant for the dissociation of Pcl5(g) to form PCl3(g) and Cl2(g) is
0.04 at 250°C. An equilibrium mixture contains 0.20 mol PC13 and 0.12 mol Cl, in a
4000 cm container.
i) Write the chemical equation.
ii) Calculate the concentration of PCIs in this container.
Answer:
a)
[tex]K_2=1.3x10^{2}atm^{-1/2}[/tex]
b)
[tex]PCl_5\rightarrow PCl_3+Cl_2[/tex]
[tex][PCl_5]=0.0375M[/tex]
Explanation:
Hello!
a) In this case, since we can see that the second reaction is equal to the half of the first reaction, we can relate the equilibrium constants as shown below:
[tex]K_2=K_1^{1/2}[/tex]
Thus, by plugging in the the equilibrium constant of the first reaction we obtain:
[tex]K_2=(1.6x10^4atm^{-1})^{1/2}\\\\K_2=1.3x10^{2}atm^{-1/2}[/tex]
b) In this case, for the described reaction we can write:
[tex]PCl_5\rightarrow PCl_3+Cl_2[/tex]
Thus, the corresponding equilibrium expression is:
[tex]K=\frac{[PCl_3][Cl_2]}{[PCl_5]}[/tex]
In such a way, since we know the equilibrium constant and the concentrations of PCl3 and Cl2 at equilibrium, we can compute the concentration of PCl5 at equilibrium as follows:
[tex][PCl_5]=\frac{[PCl_3][Cl_2]}{K}\\[/tex]
[tex][PCl_5]=\frac{\frac{0.20mol}{4L} *\frac{0.12mol}{4L} }{0.04}[/tex]
[tex][PCl_5]=0.0375M[/tex]
Best regards!
Question 10 of 25
Consider this reaction:
Mg(s) + 2H2O(1) ► Mg(OH)2(s) + H2(g)
What is the oxidation state of Mg in Mg(OH)2(s)?
A. +2
B. - 2
C. +1
D. 0
The oxidation number of Mg in Mg(OH)₂ is +2.
Hence, Option A is correct answer.
What is oxidation number?The oxidation state, or oxidation number, is defined as the hypothetical charge of an atom if all of its bonds formed with different atoms were fully ionic. It indicates the degree of oxidation of an atom in a chemical compound. Conceptually, the oxidation state may be negative, positive or zero.
Oxidation number of OH = -1
Let us suppose the oxidation number of Mg = x
Charge on compound = 0
We can write
x + 2(-1) =0
x-2=0
x = 2
Thus from the above solution we concluded that The oxidation number of Mg is +2.
Hence, Option A is correct answer.
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Can anyone please tell me what I did wrong and why the answer I put was wrong, and why the answer that is correct, right? Giving Brainliest, PLEASE help!
Answer:
Lithium is reduesednas it gains electrons gold
Answer:
Look at Lithium on the Periodic Table, look at the amount of electrons. When Lithium and Gold are together, Lithium loses while Gold(Au) gains.