Answer:
In a reactivity series, the most reactive element is placed at the top and the least reactive element at the bottom.
A fossil is 3 half-life old. Measured Uranium-235 has half-life of 704 million years. How many years old is this fossil?
Answer: Uranium is not a problem in this case, as its radioactivity is very low. This is due to the long half-life. How much uranium will decay per second with a half-life of 700 million years? This is a very insignificant figure.
the measured mass of a sample would have which units
Answer:
[tex]\longmapsto \: \frak[ hello \: mate ][/tex]
The measured mass of a sample would have unit as "Kilogram "
Becquerel placed photographic paper in a drawer with some radioactive rocks and discovered that the amount of exposure on the paper was proportional to the amount of uranium that was present in the rocks. True False
Becquerel did not discover that the amount of exposure on the paper was proportional to the amount of uranium that was present in the rocks
What is radioactivity?The phenomenon of radioactivity was discovered by the French scientist Henri Becquerel in 1896 when he placed photographic paper in a drawer with some radioactive rocks.
We have to note that Becquerel did not discover that the amount of exposure on the paper was proportional to the amount of uranium that was present in the rocks hence the stetement is false.
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Calculate the volume that 3.
60g H2 gas will occupy at stp
Answer:
mass over molarmass ×volume
90
Q3. Which of the following
Elements is likely to
form cations?
ง
A. Titanium (T:)
B. Carbon
C. Bromine
(Br)
) (Ar
D. Argon
Answer:
Titanium
Explanation:
titanium can form 4+ cations
Before balancing this equation, how many oxygen atoms are present on the product side of the following equation:
Answer:
3
Explanation:
co2 has 2 and h2o has 1
product is right side
How would you correctly prepare 125 mL of a 0.30M solution of copper(II) sulfate (CuSO4) from a 2.00M solution of CuSO4?
Answer:
see below
Explanation:
.3 M/L ( .125 L) = .0375 mole required
.0375 mole / 2 mole / l = .01875 l required
take 18.75 ml of the 2.0 solution then dilute it to 125 ml
Hydrogen has a melting point of -259 °C, and a boiling point of -253 °C. Its density at liquid state is 0.07 g/cm³. What is the physical state of Hydrogen at -250 °C? Explain your answer.
Answer:
Explanation:
Remark
-250, if you can believe it, is actually warmer than - 253. At -250 the hydrogen has gone through a phase change (a phase change means that it has gone from a liquid to a gas).
From here on as far as you are concerned, the hydrogen will stay as a gas. Later on, if all other things remain constant, you will learn that hydrogen can do some very strange things.
If a watershed suddenly receives a great deal of rainfall, what will happen to its wetlands and rivers?
Answer:
Depending on the actual amount of water, it's going to overfill.
Explanation:
If your watershed is already one that has a lot of water and is always filled, it's likely that your wetlands and rivers will start to overfill, causing a form of flooding.
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I hope this helps!
-No one
What is the balanced equation for the redox reaction between zinc and hydrochloric acid (HCl) that forms zinc(II) ions and hydrogen gas? A. 2Zn + HCl + H+ Zn2Cl + H2 B. Zn + 2H+ 2Zn2+ + H2 C. 2Zn + 2H+ 2Zn2+ + H2 + 2e- D. Zn + 2H+ 2Zn2+ + H2 + 2e-
The balanced equation for the redox reaction between zinc and hydrochloric acid (HCl) that forms zinc(II) ions and hydrogen gas is as follows:
Zn(s) + 2H+(aq) → Zn2+(aq) + H2(g)
What is a redox reaction?A redox reaction is a type of chemical reaction in which some of the atoms have their oxidation number changed.
According to this question, the redox reaction between zinc and hydrochloric acid (HCl) forms zinc(II) ions and hydrogen gas. The balanced equation is as follows:
Zn(s) + 2H+(aq) → Zn2+(aq) + H2(g)
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Finally, examine the atomic spectrum below. Estimate the wavelength
of each spectral line, then use that collection of wavelengths to try and
determine the identity of the element using the internet. This is the
kind of work a graduate student in chemistry might be assigned to do.
400
450
500
650
700
750
550 600
wavelength (nm)
Identity of the element
The estimated wavelengths and identities of the elements of spectral line in the given atomic spectrum is:
blue spectral line - 470 nm; Iron green spectral line - 490 nm; Magnesium yellow spectral line - 610 nm; Sodiumred spectral line - 660 nm; HydrogenWhat is an atomic spectrum?Atomic spectrum is the spectrum of frequencies or wavelengths of radiations absorbed or emitted when electrons transitions between on energyblevel to another.
The estimated wavelengths as well as identities of the elements of spectral lines shown above are as follows
blue spectral line - 470 nm; green spectral line - 490 nm; Ironyellow spectral line - 610 nm; Sodiumred spectral line - 660 nm; HydrogenTherefore, the wavelengths and colors of the spectral line in an atomic spectrum is useful in identifying elements.
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Choose the answer that describes the hierarchy among these three body regions.
A. The oral region is part of the facial region, and the facial region is part of the cephalic region.
B. The cephalic region is part of the facial region, and the facial region is part of the oral region.
C. The cephalic region is part of the facial region, and the facial region is part of the manual region.
D. The oral region is part of the cephalic region, and the cephalic region is part of the facial region.
Answer:
letter: B
Explanation:
thats is the true answer.
pleas heart my heart my answer
The release of aluminium ions as a result of acid rain is less significant in areas containing limestone rock - why?
Answer:
As it flows through the soil, acidic rain water can leach aluminum from soil clay particles and then flow into streams and lakes. The more acid that is introduced to the ecosystem, the more aluminum is released. Some types of plants and animals are able to tolerate acidic waters and moderate amounts of aluminum
Explanation:
How moles of Cl' are in a 45 mL of 1,4 M solution of NaCl?
Answer:
.063 moles Cl-
Explanation:
To find moles multiply molarity by volume.
1.4*.045=.063 moles Cl-
4. Calculate the total amount of heat a beaker of water would absorb sitting in the sun. The water has a mass of 500g, a specific heat of 4.184 (J/gx°C), and had a change in temperature of 22 °C.
Answer:
46024 j or 46.024 kj
Explanation:
500 gm * 4.184 j/(gm-C) * 22 C = 46024 j
The heat energy absorbed by water of mass 500 g and specific heat capacity of 4.184 J/°Cg with a temperature rise to 22 degree celsius is 46024 J.
What is specific heat capacity?Specific heat capacity of a substance is the heat energy required to raise the temperature of that substance by one degree celsius per mole. It is an intensive property and does not dependent on the total amount if the substance.
Specific heat capacity of a substance is a constant and water have this value of 4.184 J/°Cg. The heat energy q absorbed or evolved from a system is related to the specific heat capacity C , mass M and temperature change ΔT occured on the system as in equation written below:
q = mC ΔT .
The heat energy of water of mass 500 g absorbed for a temperature change of 22 °C can be calculated as follows:
q = 500 g × 22 °C × 4.184 J/°Cg
= 46024 J.
Hence, the total heat of absorption of water for the given mass and temperature change is 46024 J.
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Science Task (
The transfer of thermal energy by the movement of liquids or gases is called
Convection is the movement of fluid (this can wether be liquid or gas) and as they move, they carry heat along with them.
Answer:
Convection
More info:
Heat transfers include the following: Conduction, Convection, and Radiation.
Conduction is the transfer of heat through molecules by direct contact. This takes place in the three phases of matter, but conduction works best in materials with close contact molecules of simple molecules.Convection, (definition above)Radiation is the transfer of heat through electromagnetic waves. Unlike Conduction and Convection, Radiation doesn't need matter to help with heat transfer.I am open to corrections if I accidentally included false information :).
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What volume will 3.0 moles of O2 gas occupy at S.T.P?
Answer:
3 moles of oxygen at STP will occupy a volume of 3×22. 4=67. 2 L.
Explanation:
Which of the following is an example of the organic portion of the Earth’s outer layers?
Oxides
Coal
Sulfides
Carbonates
Answer:
Coal
Explanation:
Coal is derived from ancient plant life and thus consists largely of organic compounds.
The example of the organic portion of the Earth’s outer layers is coal.
What are the layers of earth?The earth is made up of many layer which are very important for human life and our planet earth.
The earth is basically made up of three different layers.
Crust - Crust is defined as a rocky planet's, dwarf planet's, or natural satellite's outermost solid shell.Mantle - Mantle is defined as the layer between the Earth's crust and the molten iron core, a thick layer of hot, solid rock.Core - The core are made up of two layer the outer core and the inner is the mantle.There are basically five layers of earth atmosphere.
TroposphereStratosphereMesosphereThermosphereExosphereThus, the example of the organic portion of the Earth’s outer layers is coal.
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2. A 0.2719 g sample containing CaCO3 reacted with 20.00 mL of 0.2254 M HCl. Given that HCI was excess. The excess HCl required exactly 20.00 mL of 0.1041 M NaOH to reach the end-point using phenolphthalein indicator. Determine percentage purity of CaCO3 in the sample. The reraction involved is CaCO3(s) + 2HCl(aq) → CaCl₂(aq) + 2H₂O(l) The titration reaction is HC(aq) + NaOH(aq) NaCl(aq) + H₂O(1)
The percentage purity of the calcium carbonate is 44%. The percentage purity gives the amount of pure CaCO3 in the sample.
What is excess titration?In excess titration or back titration, we neutralize the excess titrand left in a system.
We have the reaction;
CaCO3 + 2HCl ----> CaCl2 + H2O + CO2
Number of moles of HCl = 0.2254 M * 20/1000 L = 0.0045 moles
The reaction of the excess acid is according to the reaction;
HCl + NaOH ----> NaCl + H2O
Number of moles of NaOH = 0.1041 M * 20/1000 = 0.0021 moles
Since the reaction is 1:1, 0.0021 moles of HCl reacted also
Number of moles of HCl that reacted with CaCO3 = 0.0045 moles - 0.0021 moles = 0.0024 moles
If 2 moles of HCl reacts with 1 mole of CaCO3
0.0024 moles of HCl reacts with 0.0024 moles * 1/2
= 0.0012 moles
Mass of pure CaCO3 present = 0.0012 moles * 100 g/mol = 0.12g
Percent purity of the sample = 0.12g/0.2719 g * 100/1
= 44%
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What is the volume of hydrogen chloride under normal conditions, if its mass is 73 g?
Explanation:
36.5 g of HCl occupies 2.24×10-2m3 . ∴ 73 g of HCI at STP will occupy 2.24×10-236.5×732=4.48×10-2m3.
An ideal gas occupies 400ml at 270 mm Hg and 65°C. If the pressure is changed to 1.4 atm and the
temperature is increased to 100°C, what is the new volume?
Answer:
113 ml
Explanation:
PV = nRT remember T must be in Kelvin Volume in L
270 * .4 = n 62.4* 338.15
n = .005118
1.4 atm = 1.4 * 760 = 1064 mm
1064 * V = .005118 * 62.4 * 373.15
V = .113 l
What are the three main groups of macronutrients? (select three please)
minerals
proteins
fats
carboydrates
Answer:
protein, carbs, and fats.
Explanation:
Those are the three main sources of macronutrients.
(this isn't a chemistry, it's health)
Answer:
fats, carbohydrates and proteins
Explanation:
I don't know, I answered that on my test and it was correct
Which statement about geologic times are true? ~Pick multiple answers~
Answer:
the correct answers are A,D,E, and G
Explanation:
What is the product of radioactive decay 0/-1 e called?
A. An alpha particle
B. A beta particle
C. Nuclear fission
D. A gamma wave
Answer:
it represents a beta particle so the answer is B a beta particle
Answer:
The product of radioactive decay ⁰-₁e called a beta particle
B. A beta particle
How many grams are in 4.25 moles of NiS?
Answer:
386.75 grams
Explanation:
You can use dimensional analysis to help you solve for this question
1. set up a proportion
x grams
4.25 mol x x mole
2. to find the amount of grams/mol that are in NiS we find the gram formula mass (mass of all the atomic masses of each element)
Ni- 59 grams
S- 32 grams
add these together and you get 91 g/mol
3. now plug in the values and multiply across
91 grams
4.25 mol x 1 mole
when you multiply across this is equal to 386.75 grams
Describe how you might prepare disodium phosphate given a solution of phosphoric acid, 0.500 molar and a solution of sodium hydroxide base, 0.500molar.
Explanation:
When 2 moles of sodium hydroxide (NaOH) reacts with 1 mole of phosphoric acid (H3PO4) it gives 1 moles disodium phosphate Na2HPO4 and 2 moles of water.
0.5 molar solution indicates half moles of molecules are present in per ltr solution.
to prepare disodium phosphate you need to dilute phosphoric acid solution to 0.25 molar and add equal quantity of 0.5 molar solution.
[tex]2 NaOH + H_3PO_4 \: \rightarrow \: Na_2HPO_4 + 2 H_2O[/tex]
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If the cell is somehow operated under conditions in which it produces a constant voltage of 1.50 V , how much electrical work will have been done when 0.487 mL of Br2(l) has been consumed
For a cell operated to produce a constant voltage of 1.50 V, the electrical work done is mathematically given as
W=2.077*10^{-7}
What is the electrical work done?Generally, the volume of Br2 is mathematically given as
[tex]Vb=\frac{0.38*3.12}{159.809}[/tex]
Vb=7.18*10^-3ml
Therefore, the quantity of charge
q=(1.436*10^-2)*9.644*10^4
q=1.385^{-4}c
In conclusion, work done
W=Eq
W=1.50*1.385^{-4}
W=2.077*10^{-7}
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What do these 2 changes have in common?
Both are only physical changes.
Both are caused by heating.
Both are chemical changes.
Both are caused by cooling.
Answer:
Both are caused by heating. Both are Chemical changes.
Explanation:
Water evaporates from the Sun's heat and is transformed into a gas. Sediment is the particles of an object. When heat hits it, it starts breaking up, or in dry cases, heating and cracking.
During photosynthesis, a green plant produces 122 mL of oxygen gas at STP. What mass of glucose
(C6H12O6) is produced during this reaction?
6CO2+ 6H2O > C6H12O6+ 602
Show all steps (Answer: 0.164g)
Answer:
About 0.164 g of glucose.
Explanation:
We can determine the mass of glucose produced given the volume of oxygen gas produced with stoichiometry.
Recall that at STP, a mole of any gas occupies a volume of 22.4 L.
From the reaction, six moles of oxygen gas is produced for every one mole of glucose.
Lastly, the molecular weight of glucose is 180.18 g/mol.
Therefore:
[tex]\displaystyle \begin{aligned} 122\text{ mL O$_2$} & \cdot \frac{1\text{ L O$_2$}}{1000\text{ mL O$_2$}}\cdot \frac{1\text{ mol O$_2$}}{22.4\text{ L O$_2$}} \cdot \frac{1\text{ mol C$_6$H$_{12}$O$_6$}}{6\text{ mol O$_2$}} \cdot \frac{180.18\text{ g C$_6$H$_{12}$O$_6$}}{1\text{ mol C$_6$H$_{12}$O$_6$}} \\ \\ & = 0.164\text{ g C$_6$H$_{12}$O$_6$}} \end{aligned}[/tex]
Therefore, about 0.164 g of glucose is produced.
Which of the following is an ionic compound?
A. N2O B. CO C. HCL D. Na2O
Answer:
D. Na2O
Because we already know that sodium oxide is a binary ionic compound because it contains one metal cation and one non-metal anion.
Answer:
D. Na2O
Explanation:
Sodium oxide (Na2O) is an ionic compound. Its constituent atoms are, respectively, a metal and a non-metal.
Sodium (Na), as a metal, will attempt to lose electrons to reach an octet state. Oxygen (O2), as a non-metal, will attempt to gain electrons to reach an octet state.
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