Answer: True
Explanation:
Index fossils are found throughout the world and come from organisms which existed during limited periods of geologic time. Which of the following best describes what index fossils can be used to determine?
A.
the age of a layer of rock
B.
when an organism first appeared on Earth
C.
how an organism evolved over time
D.
the way an organism went extinct
Answer: A. the age of a layer of rock
Explanation:
Index fossils are of organisms that lived over a wide area. They lived for a fairly short period of time.
Index fossils are found throughout the world and come from organisms which existed during the limited periods of geologic time. Index fossils can be used to determine the age of a layer of rock. Thus, the correct option is A.
What is Index fossil?Index fossil is any kind of animal or plant that is preserved in the rock record of the Earth which is characteristic of a particular span of geologic time. A useful index fossil must be distinctive or is easily recognizable, abundant, and have a very wide geographic distribution and also a short range through time.
Index fossils are used to define the geological periods or the age of a layer of rock. These fossils can be defined as the commonly found, widely distributed fossils that are limited in time span. If a person finds an index fossil in a given layer, then he has bounds on the age of the layer.
Therefore, the correct option is A.
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When a chemical reaction occurs,
O a phase change takes place
o the physical and chemical properties of the products are different from the reactants
O the physical and chemical properties of the reactants are the same as the properties of the products
o the compounds can be separated by physical means
Answer:
D. the physical and chemical properties of the products are different from the reactants
Explanation:
NEED HELP ASAP!!!!!!!!!!!!!!!
Where will you encounter the least amount of life in the oceans?
abyssal plains (the ocean's bottom)
the beach
the top 200 meters of the ocean
inter tidal zone
Answer:
The abyssal plains
Explanation:
this is because it is so dark and devoid of resources that it is hard for most forms of life to survive
pls make me brainliest :) I'm trying to become an Ace
Answer:
abyssal
Explanation:
What does X represent for this transmutation?
96242Cm + X→ 98245Cf + 01n
gamma
+10e
24He
−10e
Answer:
24He
Explanation:
When a nuclide is bombarded with alpha particles, we notice an increase in its mass and charge since an alpha particle has a mass of four and a charge of +2. recall that nuclear equations must be balanced. That is, the masses and charges on the left hand six and the right hand side of the nuclear reaction equation must be exactly the same.
Looking at the nuclear reaction at hand, the total mass on the left hand side has to be 246 while the total charge on the left hand side of the equation will be 98. Coming over to the right hand side, the total masses are also found to be the same as a neutron with no charge and a mass of 1 is produced. Hence the nuclear reaction equation is balanced when an alpha particle (helium nucleus) is substituted for X in the equation.
Answer:
24HE
I took the test!
what is the shortest half life
Answer:
Hey!
Your answer is element A
Explanation:
Using the graph, the element A's emission of radioactive particles ends approximately after 6 years...
A HALF-LIFE IS "HALF" OF THAT TIME PERIOD!
So if the radiation goes for 6 years the half-life is 6 divided by two which gives you 3 years!
The rest however have a longer half-life...
Because they all end at 14 yrs so their half-life in 7 years!
HOPE THIS HELPS!!
The _____ of a weak acid is strong.
a. conjugate acid
b. conjugate base
c. acid
d. base
Answer: conjugate base
Explanation:
According to the Bronsted-Lowry conjugate acid-base theory, an acid is defined as a substance which looses donates protons and thus forming conjugate base and a base is defined as a substance which accepts protons and thus forming conjugate acid.
A weak acid has a strong conjugate base whereas a strong acid has a weak conjugate base. Similarly a weak base has a strong conjugate acid whereas a strong base has a weak conjugate acid.
[tex]CH_3COOH+NH_3\rightarrow CH_3COO^-+NH_4^+[/tex]
Acetic acid [tex]CH_3COOH[/tex] is weak acid which has strong conjugate base [tex]CH_3COO^-[/tex]
please helpppppppppp
Select the TRUE statements about the carbon cycle
The carbon cycle is the process in which carbon travels from the atmosphere into organisms and the Earth and then back into the atmosphere.
Plants take carbon dioxide from the air and use it to make food.
Animals eat food and the carbon is stored in their bodies or released during cellular respiration.
Water (H2O) is cycled around the Earth
the carbon cycle is the process in which carbon travels from the atmosphere into organisms and the earth and then back into the atmosphere
Which word equation represents a neutralization reaction? *
base + acid salt + water
base + salt → water + acid
salt + acid base + water
salt + water → acid + base
Answer:
A
Explanation:
Neutralization reaction is
base + acid ---> salt + water.
A hydrate is typically a crystalline compound in which water molecules are chemically bound to another compound or an element. When CuSO4⋅ 5H2O is heated in a crucible, there is a loss of water. How should a student determine the amount of water lost?
a.Subtract the mass of the CuSO4 from the mass of CuSO4⋅ 5H2O
b.Subtract the mass of the CuSO4⋅ 5H2O from the mass of CuSO4
c.Add the masses of CuSO4⋅ 5H2O and CuSO4
d.Multiply the masses of CuSO4⋅ 5H2O and CuSO
When CuSO4⋅ 5H2O is heated in a crucible, there is a loss of water. Subtract the mass of the CuSO4⋅ 5H2O from the mass of CuSO4 to determine the amount of water lost. Therefore, option B is correct.
What do you mean by the compound ?A substance made up of two or more components is called a compound. Table salt, water, and carbon dioxide are a few examples of compounds.
Chemical substances have no electrical charge. In most cases, ionic compounds are created when a metal interacts with a nonmetal. The reaction between two nonmetals produces covalent compounds.
Elements are unadulterated substances made up of only one kind of atom. Compounds are substances that are created when two or more different types of elements are chemically combined in predetermined ratios.
To determine the amount of water lost subtract the mass of the CuSO4⋅ 5H2O from the mass of CuSO4.
Thus, option B is correct.
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You are in the room with several objects, the temperature in the room is 21 celcius, what can you assume about the temperatures of the objects in the room?
Answer:the objects will be about the same temperature as the room
Explanation:
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Answer:
condensation: moisture builds up on window; dew forms on blades of grass
deposition: snow is made inside a cloud; frst froms on window?
Explanation:
PLEASE HELP ;)
Tristan accidentally spilled a substance with an unknown ph on his hands and it burns. Why should he wash his hands immediately with soap and water?
a. the substance spilled on his hand is an acid. The acid in the soap will neutralize the acid to make it stop hurting.
b. The substance spilled on his hand is an acid. The base in the soap will neutralize the acid to make it stop burning.
c. The substance spilled on his hands is a base. The base in the soap will neutralize the acid to make it stop hurting.
d. The substance spilled on his hand is an base. The base in the soap will neutralize the base to make it stop hurting.
Answer:
b. The substance spilled on his hand is an acid. The base in the soap will neutralize the acid to make it stop burning.
Explanation:
In this case, the substance spilled on the hand is an acid, so it will require neutralization. In neutralization reactions, you have an acid and a base, which will be soap. This reaction is known as saponification.
A gas was held at a constant temperature in a closed system. The initial
pressure of the gas was 1.20 atm, while its initial volume was 2.30 L. The
final volume of the gas was 1.50 L. What was the final pressure of the gas
to the nearest hundredth of an atmosphere?*
Answer:
1.84 atm
Explanation:
P2=V1P1/V2
Temp is irrelevant because it is constant, so all you have to do is rearrange the ideal gas law.
You can check this by knowing P and V at constant T have an inverse relationship and therefore makes this the correct answer.
- Hope that helps! Please let me know if you need further explanation.
2. Find out the enthalpy change of the CH4 from solid Carbon and Hydrogen gas. C (s)+ 2H2 (g)(CH4(g) (H( = ?
Use the following three equations:
C (s)+ O2 (g)(CO2(g) (H( = -393.5 kJ
H2 (g)+1/2 O2 (g)(H2O(l) (H( = -285.8 kJ
CH4 (g)+ 2O2 (g)( CO2(g)+ 2H2O(l) (H( = -890.3 kJ
Answer:
Approximately [tex]-74.8\; \rm kJ \cdot mol^{-1}[/tex].
Explanation:
Number the three reactions with known enthalpy changes:
[tex]\begin{aligned}& {\rm C\; (s) + O_2\; (g) \to CO_2\; (g)} & \quad \Delta H = -393.5\; \rm kJ\cdot mol^{-1}& \quad (1) \\ & {\rm H_2\; (2) + \frac{1}{2} O_2\; (g) \to H_2O\; (l)} & \quad \Delta H = -285.8\; \rm kJ\cdot mol^{-1} & \quad (2) \\ & {\rm CH_4\; (g) + 2\; O_2\; (g) \to CO_2\; (g) + 2\; H_2O\; (l)} & \quad \Delta H = -890.3\; \rm kJ\cdot mol^{-1} & \quad (3)\end{aligned}[/tex].
The goal is to find a way to combine these three reactions to obtain: [tex]\rm C\; (s) + 2\; H_2\; (g) \to CH_4\; (g)[/tex].
Assume that the three known reactions are combined in this way:
[tex]a \times (1) + b \times (2) + c \times (3)[/tex].
That corresponds to:
[tex]\begin{aligned} & a\; \mathrm{C\; (s)} + \left(a + \frac{1}{2}\, b + c\right) \; \mathrm{O_2\; (g)} + b\; \mathrm{H_2\; (g)} + c\; \mathrm{CH_4\; (g)} \\ & \to (a + c)\; \mathrm{CO_2\; (g)} + (b+ 2\,c )\; \mathrm{H_2O\; (l)}\end{aligned}[/tex].
Compare the coefficients of this reaction with that of the desired reaction:
[tex]\rm C\; (s) + 2\; H_2\; (g) \to CH_4\; (g)[/tex].
Note that some species (e.g., [tex]\rm CH_4\; (g)[/tex]) appeared on the wrong side of the equation. Their desired coefficient should be the opposite of their true coefficient. For example, the coefficient of [tex]\rm CH_4\; (g)[/tex] is supposed to be [tex]1[/tex]. However, because it appeared on the wrong side of the equation, its desired coefficient would be [tex]-1[/tex].
The coefficients of species that are not in the desired equation should be zero.
[tex]\begin{array}{|c|c|c|}\cline{1-3}\text{Species} & \text{Coefficient}& \text{Desired Coefficient} \\ \cline{1-3} \mathrm{C\; (s)}} & a & 1 \\ \cline{1-3} \mathrm{O_2\; (g)} & a + (1/2)\, b + c & 0 \\ \cline{1-3} \mathrm{H_2\; (g)} & b & 2 \\ \cline{1-3}\mathrm{CH_4\; (g)} & c & -1\\ \cline{1-3} \mathrm{CO_2\; (g)} & a + c & 0 \\ \cline{1-3} \mathrm{H_2O\; (l)} & b + 2\, c & 0\\ \cline{1-3}\end{array}[/tex].
Solve for [tex]a[/tex], [tex]b[/tex], and [tex]c[/tex]:
[tex]a = 1[/tex].[tex]b = 2[/tex].[tex]c = -1[/tex]. In other words, the third equation is inverted before being added to the other two equations.In other words, the desired equation is equal to [tex]1 \times (1) + 2 \times (2) - 1 \times (3)[/tex].
By Hess's Law, the enthalpy of the desired equation will be:
[tex]\begin{aligned}& 1\times \Delta H (1) + 2 \times \Delta H (2) - 1\times \Delta H(3) \\ &\approx -393.5 + 2 * (-285.8) - (-890.3) \\ &= -74.8\; \rm kJ \cdot mol^{-1} \end{aligned}[/tex].
A 350. mL air sample collected at 35 degrees C has a pressure of 556 mm Hg.
What pressure will the air exert if it is allowed to expand to 425 mL at 57 degrees
C? Show your work in the space below.
Answer:
485 torr
Explanation:
Explanation:
We can solve this equation using the combined gas law:
P1V1/T1=P2V2/T2
Remember, always use the absolute (Kelvin) temperature when working with gas equations.
The temperature conversions are
T1=C+273=35o+273=308K
T2=57C+273=330K
Since we're trying to find the final pressure, let's rearrange this equation to solve for
P2:
P2=P1V1T2/T1V2
Our known values:
P1= 550 torr
V1=350mL
T1=308K
V2=425"mL
T2=330K
Let's plug these into the equation to find the final pressure:
The final pressure after it is subjected to these changes is thus 485torr
Write the beta decay equation for the following isotope: 91 38 Sr? Please write out steps
Answer:
[tex]\rm _{38}^{91}Sr \longrightarrow \, _{-1}^{0}e + \, _{39}^{91}Y[/tex]
Explanation:
The unbalanced nuclear equation is
[tex]\rm _{38}^{91}Sr \longrightarrow \, _{-1}^{0}e \, + \, ?[/tex]
Let's write the question mark as a nuclear symbol.
[tex]\rm _{38}^{91}Se} \longrightarrow \, _{-1}^{0}e \, + \, _{Z}^{A}X[/tex]
The main point to remember in balancing nuclear equations is that the sums of the superscripts and the subscripts must be the same on each side of the equation.
Then
98 = 0 + A, so A = 98 - 0 = 98, and
38 = -1 + Z, so Z = 38 + 1 = 39
Then, your nuclear equation becomes
[tex]\rm _{38}^{91}Sr \longrightarrow \, _{-1}^{0}e + \, _{39}^{91}X[/tex]
Element 39 is yttrium, so the balanced nuclear equation is
[tex]\rm _{38}^{91}Sr \longrightarrow \, _{-1}^{0}e + \, _{39}^{91}Y[/tex]
What is the answer ?
Answer: c
Explanation: an xray wave does have a higher frequency than an infrared wave.
Answer:
Explanation:c
What is the purpose of the part of the male reproductive system that is
highlighted below?
A. Mixes sperm and semen
B. Creates the fluid in semen
C. Manufactures sperm cells
D. Stores sperm cells until they mature
O
Answer:
A
Explanation:
Unlike the female reproductive system, the most parts of the male reproductive system are located outside the body. The mentioned part in the given diagram is urethra and it Mixes sperm and semen. The correct option is A.
What is male Reproductive system?The male reproductive system includes the testes, scrotum, spermatic ducts, male accessory glands and phallus. All these organs work together to produce sperms, the male gamete, male sex hormones and other components of semen.
The phallus and urethra are the parts of both the reproductive and urinary systems. Scrotum, seminal vesicles, vas deferens, testicles and prostate constitute all the remaining male reproductive system.
The urethra is a tube like structure which is the region included in the urinary tract that takes the urine from the bladder where the semen is ejaculated.
Thus the correct option is A.
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What is the key building block of living tissue and ecosystems?
Hope u can help!
Answer:
Your answer is cells. Hope this helps!
Review the following chemical equation: Find the molar ratio between C6H6 to
carbon dioxide, CO2. 2C6H6 + 1502 YEILDS 6H20 - 12C02
Answer:
[tex]\frac{1}{6}[/tex]
Explanation:
Molar ratio is defined as the ratio of number of moles of reactants or products in a balanced chemical equation.
In this balanced equation, the number of C6H6 molecules react to form 12 CO2 molecules.
Thus, the molar ratio between C6H6 to carbon will be equal to 2 moles of C6H6 divided by 12 moles of CO2
[tex]\frac{2}{12}\\\frac{1}{6}[/tex]
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A student determines that she used 0.0665 mol of sodium hydroxide (NaOH) to completely titrate 25.00 mL of sulfuric acid solution (H2SO4). What is the molarity of the sulfuric acid?
0.00131 M
0.00262 M
1.31 M
2.62 M
A student determines that she used 0.0665 mole of sodium hydroxide (NaOH) to completely titrate 25.00 mL of sulfuric acid solution. The molarity of the sulfuric acid is 1.31 M. Therefore, option C is correct.
What is molarity?Number of moles of solute per liter of solution is known as molarity.
The balanced chemical equation for the reaction between sodium hydroxide and sulfuric acid is:
2 NaOH + H₂SO₄ → Na₂SO₄ + 2 H₂O
According to the balanced equation, one mole of sulfuric acid reacts with two moles of sodium hydroxide. Therefore, the number of moles of sulfuric acid in the titrated solution can be calculated as:
moles of H₂SO₄ = (moles of NaOH) / 2
moles of H₂SO₄ = 0.0665 mol / 2
moles of H₂SO₄ = 0.03325 mol
The volume of the sulfuric acid solution used in the titration is 25.00 mL, which is equivalent to 0.02500 L. The molarity (M) of the sulfuric acid can be calculated as:
Molarity of H₂SO₄ = moles of H₂SO₄ / volume of H₂SO₄ solution in liters
= 0.03325 mole / 0.02500 L
= 1.31 M
Thus, option C is correct.
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Need help with these three pls!!
Answer:
True True False
Explanation:
Valves are in most veins (to prevent backflow). Also valves in the chart and an in an combustion engine.
So the first statement is True.
Valves control the flow rate and direction of fluid within a closed system. So the second statement is True.
1 Pa = 1 N/m² So since 1 Pa equals to one newton per square metre the third statement is False.
A plant was placed in the corner of a room away from a window. What might you observe about the plant after five days?
Select one:
The plant is leaning toward the window.
The plant is not affected by the light in the window.
The plant is standing straight up from the pot.
The plant is leaning away from the window.A plant was placed in the corner of a room away from a window. What might you observe about the plant after five days? Select one: The plant is leaning toward the window. The plant is not affected by the light in the window. The plant is standing straight up from the pot. The plant is leaning away from the window.
Answer:
1. A. The plant leans toward window.
Explanation:
Plants need light to perform photosynthesis and live. Therefore, this means the plant will always lean toward light in order to survive.
- Hope that helps! Please let me know if you need further explanation.
Answer
Last one I think
Explanation:
which is correct? not sure which is right
Answer:
butane
Explanation:
Which is produced by nuclear fusion?
A. hydrogen
B. electricity
C.
solar radiation
D. gasoline
Answer:
c
Explanation:
Which of the following is the energy that comes from changes in an atom’s nucleus?
a. thermal energy
b. nuclear energy
c. light energy
d. electrical
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Answer:
1. sublimation
2.melting
3.melting
4.sublimation
Explanation:
melting is a process when solid changes to liquid
Sublimation is the transition of a substance directly from the solid to the gas state, without passing through the liquid state.
A(n)
image cannot be projected and forms where light rays appear to originate.
Answer:
Eu não sei o que você está dizendo, mas boa sorte
Answer: Virtual
Explanation: A virtual image is an image that can not be formed on a screen. This type of an image is formed when the rays of light appear to meet at a point after reflection or refraction. Virtual images are always erect or upright.
What is the oxidation state of Fe(s)
The oxidation state is zero for Fe (s)
anybody know where to find this packet at online ?
