Scientists hypothesize that a certain species of animal existed in the past.
But, fossils of the species have never been found. Which two statements
could explain why?
A. There were very few members of the species.
B. Their bodies decomposed quickly.
O C. Their bodies contained radioactive atoms.
D. Minerals seeped into their bones.
SUBMIT
Answer: Fossils of the species have never been found because:-
a. There were few members of the species.
d. Their bodies decompose quickly.
For an organism to become fossil it is important that it do not decompose before it get buried by sediments.
What are fossils?
A fossil is any preserved remains, impression, or trace of any once-living thing from a past geological age.
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Answer: The answer is B and A.
Explanation:
I took the test!
What are thermal plasmas?
plasmas that have particles that collide infrequently
plasmas that reach a temperature equal to their surroundings
plasmas that do not reach thermal equilibrium
plasmas that have only a few particles ionized at any given mom
Answer:
B
Explanation:
How many Liters of 18 M H2SO4 are needed to make 0.5 L of 1.5 M H2SO4
Answer:
0.04 L
Explanation:
The following data were obtained from the question:
Concentration of stock solution (C1) = 18M
Volume of stock solution needed (V1) =?
Concentration of diluted solution (C2) = 1.5M
Volume of diluted solution (V2) = 0.5L
The volume of the stock solution needed can be obtain by using the dilution formula.
This is illustrated below:
C1V1 = C2V2
18 x V1 = 1.5 x 0.5
Divide both side by 18
V1 = (1.5 x 0.5)/18
V1 = 0.04L
Therefore, the volume of the stock solution needed is 0.04L.
2. If the reaction of 5.75 moles of sodium with excess hydrofluoric acid is able to produce 2.49 mol H2, what is the percent yield of hydrogen gas?
Unbalanced equation:
Na + HF –> NaF + H2
94.2%
86.5%
43.3%
23.1%
Answer:
86.5%
Explanation:
We'll begin by writing the balanced equation for the reaction. This is given below:
2Na + 2HF –> 2NaF + H2
Next, we shall determine the theoretical yield of the hydrogen gas, H2. This is illustrated:
From the balanced equation above,
2 moles of Na reacted to produce 1 mole of H2.
Therefore, 5.75 moles of Na will react to produce = (5.75 x 1)/2 = 2.88 moles of H2.
Therefore, the theoretical yield of Hydrogen gas, H2 is 2.88 moles.
Finally, we shall determine the percentage yield of Hydrogen gas, H2. This can be obtained as follow:
Actual yield of H2 = 2.49 moes
Theoretical yield of H2 = 2.88 moles
Percentage yield of H2 =.?
Percentage yield = Actual yield /Theoretical yield x 100
Percentage yield = 2.49/2.88 x 100
Percentage yield = 86.5%
Therefore, the percentage yield of Hydrogen gas, H2 is 86.5%.
The functional group for an ester is: RCHO RCOOH RCOOR ROH
Answer:
RCOOR
Explanation:
Odyssey ware
RCOOR is the functional group for an ester. An ester is an organic molecule created when an acid and an alcohol interact. The general structure of the compound is RCOOR, where R is an aryl or alkyl group.
What is the way for the structure ?This functional group is made up of an alkyl or aryl group (R) and a carbonyl group (C=O) linked to an oxygen atom. Two additional carbon atoms, one of which is a member of the carbonyl group and the other of which is a member of the alkyl or aryl group, are joined to the oxygen atom.
The connection between the oxygen atom and the hydrogen atom of the acid is broken during the interaction of an acid with an alcohol to create an ester.of a fresh connection between the oxygen atom and the alcohol's alkyl or aryl group. As a result, the RCOOR functional group is created.
Esters are significant organic substances with many different uses. They serve as solvents and are employed in the synthesis of flavours, perfumes, polymers, medicines, and other products. They are also employed in the creation of fragrances and cosmetics, as well as as lubricants. Other organic compounds can be made using esters as intermediates.
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Calculate the heat of reaction, ∆H°, for the following:
3FeCl2(s) + 4H2O(g) Fe3O4(s) + 6HCl(g) + H2(g)
Answer:
562.76 kJ
Explanation:
∆H° (kJ) is the total of the heats of formation of the products minus the total of the heats of formation of the reactants.
NB: look up the heats of formation of the compounds in the heats of formation reference tables, it is found at the back of most chemistry text
heats of formation of the products (i.e. Fe₃O₄(s) , 6HCl(g) , H₂(g) ) = -1120.9 + 6(-92.3)+ 0 = -1674.7 kJ
heats of formation of the reactants (i.e. 3FeCl₂(s) , 4H₂O(g) ) =3(-423.42) + 4(-241.8) = -2237.46kJ
∆H° = -1674.7 kJ - (-2237.46kJ) =562.76 kJ
For each of the esters provided, identify the alcohol and the carboxylic acid that reacted.
52. Methyl propanoate+_________
53. Ethyl methanoate+__________
Answer:
52. The alcohol USED => methanol, CH3OH
The carboxylic acid USED => propanoic acid, CH3CH2COOH.
53. The alcohol USED => Ethanol, CH2CH3OH
The carboxylic acid USED => Formic acid, HCOOH.
Explanation:
52. To obtain Methyl propanoate, CH3CH2COOCH3, we simply react propanoic, CH3CH2COOH and methanol, CH3OH together as shown below:
CH3CH2COOH + CH3OH —> CH3CH2COOCH3 + H2O
The alcohol used: methanol, CH3OH
The carboxylic acid used: propanoic acid, CH3CH2COOH.
53. To obtain Ethyl methanoate, HCOOCH2CH3, we simply react
Formic acid, HCOOH and ethanol, CH3CH2OH together as show below:
HCOOH + CH3CH2OH —> HCOOCH2CH3 + H2O
The alcohol USED => Ethanol, CH2CH3OH
The carboxylic acid USED => Formic acid, HCOOH.
At a certain temperature, Ke = 3 for the reaction NO3(g) NO(g) + O2(g) Find the direction of thereaction if at some point in time in a 1.0 vessel the following respective concentrations were measured; [NO] = 2.0 mol/L, [O2] = 1.0 mol/L and NO3(g) = 0.75 mol/L.
The overall process of photosynthesis has the balanced chemical equation 6CO, +6H,0 CH.0, 60, What does this tell you about the relative amounts of carbon
dioxide and water consumed in this process?
A. For every six moles of carbon dioxide consumed, one mole of water is consumed
B. For every mole of carbon dioxide consumed, one mole of water is consumed
C. For every gram of carbon dioxide consumed, one gram of water is consumed
D. For every six grams of carbon dioxide consumed, one gram of water is consumed.
Answer:
(C)
Explanation:
Because of the physics of it.
According to the overall equation of photosynthesis as follows: 6CO2 + 6H2O = C6H12O6 + 6O2, for every mole of carbon dioxide consumed, one mole of water is consumed.
What is photosynthesis?Photosynthesis is the process by which plants and other photoautotrophs convert light energy into chemical energy.
Photosynthesis makes use of carbon dioxide and water to produce glucose and oxygen as follows:
6CO2 + 6H2O = C6H12O6 + 6O2
This chemical equation suggests that for every mole of carbon dioxide consumed, one mole of water is consumed.
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Which process is based on repulsion of oil and water?
Answer:
We can seprate oil and water by the process of seprating funnel
If the pH of a solution is 7.6, what is the pOH? A. 6.4 B. 8.4 C. 5.4 D. 7.4
Answer:
6.4
Explanation: pH
+
pOH
=
14
So if
pH
=
7.6
then
pOH
=
14
−
pH
=
6.4
Explanation:
Wrote this out spaced so it's more clear.
Which lifestyle is most likely to lead to infertility in a male ?
A man who works as a mechanic
A man who works as a computer programmer and sits at desk magority of the day
A semi professional athlete
A man who works for a company’s that applies pesticides to lawns
Answer:
The second on, A man who works as a computer programmer and sits at desk magority of the day.
Explanation:
Answer:
Explanation:
The only answer I can think as being possible is the last one. Pesticides are chemicals that go after unwanted animal life. They do not know that they should not attack human beings.
Infertility could very well be one of the side effects of a pesticide. There are others as well. Some pesticides go after the central nervous system (think mice and rats) and those are dangerous to use and to leave around.
The others all involve occupations that either require authentic abilities or mental astuteness. Neither should affect a man's ability to reproduce.
Nitrogen dioxide and water react to produce nitric acid, HNO3,
and nitrogen oxide.
3NO2(g) + H2O(l) — -→ 2HNO3(aq) + NO(g)
a. How many grams of H20 are required to react with 28.0 g
of NO2?
b. How many grams of NO are produced from 15.8 g of H2O?
c. How many grams of HNO3 are produced from 8.25 g of NOZ?
Answer:
Explanation:
a )
3NO₂(g) + H₂O(l) — -→ 2HNO₃(aq) + NO(g)
3 x 46 g 18 g 2 x 63 g 30 g
138 g of NO₂ requires 18 g of H₂O
28 g of NO₂ requires ( 18 / 138) x 28
= 3.65 g of H₂O.
b )
18 g of H₂O produces 30 g of NO gas
15.8 g of H₂O produces ( 30/18 ) x 15.8
= 26.33 g of NO gas .
c )
138 g of NO₂ produces 126 g of HNO₃
8.25 g of NO₂ produces (126 / 138 ) x 8.25
= 7.53 g of HNO₃
How many grams of water are produced when 2.50 mol oxygen reacts with hydrogen?
H2 + O2 + H2O
Select one:
a. 45.0 g
b. 22.5 g
c. 90.0 g
O d. 3.6 g
PLEASE HELP
Answer:
it is 90.0
Explanation:
In the equation 2KCIO3 → 2KCI + 302, how many moles of oxygen are produced when 12.61 mol of
KCIO3 decompose completely?
Select one:
O a. 19
Ob. 8.4
O c. 6.3
O d. 13
PLEASE I AM BEGGING PLEASE HELP ME
Answer:
A 19
Explanation:
2 mole of KClO3 produces 3 mole of O3
2 : 3
1 : 3/2
12.61 : 3/2 × 12.61
12.61 : 18.9
12.61 mole of KClO3 produces 18.9mole of O2.
The pH of a substance can only be determined when it is
a) dried in a powder
b) frozen
c) dissolved in water
d) heated
The pH of a substance can only be determined when it is frozen. Hence, option B is correct.
What is pH?pH stands for Hydrogen potentials.
The use of the pH scale is one practical way of quantitatively determining how acidic something is.
If the pH of a solution is less than 7, it is acidic. If the pH is 7, the solution is neutral and if the pH is greater than 7,the solution is basic.
The pH of a substance can only be determined when it is frozen. Hence, option B is correct.
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In the past mining companies were not made responsible for the clean-up of any of
the mine sites. As a result, abandoned mines had a severe impact on the
environment in Ontario. Which of these is not a result of these mining practices?
a)
Chemical reactions producing sulphuric acid decrease soil and water ph in the
area.
b)
Acid leaching dissolves metals found in the soil thus allowing them to enter
the water system.
c)
Heavy metals which are left tailing ponds can dissolve and enter the water
system.
d)
Old and inefficient mining smokestacks contaminate the soils around
abandoned mine sites.
Q10. Calcium fluoride can be made from the reaction of calcium metal with fluorine gas. The image shows this reaction. Explain how the product is formed in terms of electron movement and what the final electron configurations are
Answer:
The answer to your question is given below
Explanation:
In this reaction, the calcium metal, Ca loses two electrons to form calcium ion, Ca^2+ and two fluorine atoms, F receives the two electrons to form two fluoride ion, F^-.
This is illustrated by the following equation:
Ca —> Ca^2+ + 2e
2F + 2e –> 2F^-
Ca + 2F + 2e —> Ca^2+ + 2F^- + 2e
Cancel out 2e
Ca + 2F —> Ca^2+ 2F^-
Thus, the electronic configuration can be written as follow:
Before combination:
Calcium, Ca (20) => 2, 8, 8, 2
Two fluorine atom, F (9) => 2, 7 and 2, 7
After combination:
Calcium ion, Ca^2+ => 2, 8, 8
Two fluoride ion, F^- => 2,8 and 2,8
Determine the [H+] or [OH−] for each of a solutions at 25°C.
Solution B: [H3O+] = 9.99 x 10^-9 M
Solution B: [OH-] = ?
Solution C: [H3O+] = 0.000777 M
Solution C: [OH-] = ?
Answer:
Solution B: [OH-] = 1×10^–6 M
Solution C: [OH-] = 1×10^–6 M
Explanation:
Solution B:
Hydronium ion concentration, [H3O+] = 9.99×10^–9 M
Hydroxide ion concentration, [OH-] = ?
The Hydroxide ion concentration, [OH-] can be obtained as follow:
[H3O+] × [OH-] = 1×10^–14
9.99×10^–9 × [OH-] = 1×10^–14
Divide both side by 9.99×10^–9
[OH-] = 1×10^–14 / 9.99×10^–9
[OH-] = 1×10^–6 M
Therefore, the Hydroxide ion concentration, [OH-] is 1×10^–6 M
Solution C:
Hydronium ion concentration, [H3O+] = 0.000777 M
Hydroxide ion concentration, [OH-] = ?
The Hydroxide ion concentration, [OH-] can be obtained as follow:
[H3O+] × [OH-] = 1×10^–14
0.000777 × [OH-] = 1×10^–14
Divide both side by 0.000777
[OH-] = 1×10^–14 / 0.000777
[OH-] = 1.29×10^–11 M
Therefore, the Hydroxide ion concentration, [OH-] is 1.29×10^–11 M
1. Give IUPAC for the following compound
Answer:
Ethane
Explanation:
Plants can only
cause mechanical weathering.
Please select the best answer from the choices provided
OT
OF
Answer:
Ice wedging, pressure release, plant root growth, and abrasion can all cause mechanical weathering. in the cracks and pores of rocks, the force of its expansion is strong enough to split the rocks apart. This process, which is called ice wedging, can break up huge boulders.
Answer:
f
Explanation:
1. A 10.0 g sample of propane, C3H8, was combusted in a constant-volume bomb
calorimeter. The total heat capacity of the bomb calorimeter and water was 8.0
kJ/°C. The molar heat of combustion of propane is -2 222 KJ/mol. If the starting
temperature of the water was 20 °C, what will be the final temperature of the
bomb calorimeter?
Answer:
The final temperature of the bomb calorimeter is 82.98°C
Explanation:
The given information are;
The mass of the propane sample = 10.0 g
The heat capacity of the bomb calorimeter = 8.0 kJ/°C
The molar heat of combustion of propane is -2,222 kJ/mol.
The starting (initial) temperature of the water, T₁ = 20°C
The final temperature of the bomb calorimeter = T₂
The molar mas of propane = 44.1 g/mol
The number of moles, n, of propane present in 10.0 g of propane is found as follows;
[tex]Number \ of \ moles \ of \ propane, \ n = \dfrac{Mass \ of \ propane}{Molar mass \ of \ propane} = \dfrac{10}{44.1} = 0.227 \ moles[/tex]Which gives;
The heat, Δh, released from the combustion of 10.0 g of propane = 0.227 × -2222 kJ/mol
Δh = -503.85 kJ/mol
Heat gained by the calorimeter = Heat released from the combustion of 10.0 g of propane = 503.85 kJ/mol
Change in heat, Δh[tex]_c[/tex] in the calorimeter = Heat capacity × Temperature change
Δh[tex]_c[/tex] = m × C
503.85 kJ/mol = 8.0 kJ/°C × (T₂ - 20°C)
T₂ = -503.85 kJ/mol/(8.0 kJ/°C) + 20°C = 82.98°C
The final temperature of the bomb calorimeter = 82.98°C
Consider preparing ammonia gas by the following reaction:
N2(g) + 3H2(g)
===>
2NH3(g)
If you have 28.02 g of N2 and excess H2, how many grams of NH3(g) can be produced.
6.06 g
14.01 g
34.08 g
68.16 g
28.02 g
Answer:
34.08 g
Explanation:
Take the atomic mass of N=14.0, H=1.0/
no. of moles=mmass/molar mass
no. of moles of N2 used = 28.02 / (14x2)
=1.0007mol
From the equation, the mole ratio of N2 : NH3 = 1: 2,
so one mole of N2 produces 2 moles of NH3.
Using this ratio, we can deduce that the no. of moles of NH3 = 1.0007x2
= 2.001428mol
mass = no. of moles x molar mass
Hence,
mass of NH3 produced = 2.001428 x (14+1x3)
= 34.03
≈C
procedure to find out if the penny is real copper with copper wire
Answer:
Four ways to test a copper penny are given below:-
Explanation:
Firstly, take a quick look only at the color of the penny. Zinc pennies may appear patchy, irregular whereas copper-gold coins may seem more probable to be orange or even chocolate. Secondly, drop your penny on the floor and hear the noise it's making. The copper penny would have a "started to ring" sound in this situation, whereas the zinc penny should "clunk." Third, you can weigh the centimeter. You'll need an accurate scale weighing in grams. The penny of copper will weigh 3.11 grams while the penny of zinc weighs 2.5 grams. In the end, look at the date. If your penny was taken out of circulation before 1982, 95 percent copper and 5 percent zinc will be made. Beginning in 1982, pennies had just 2.5 percent copper and 97.5 percent zinc in them. Pennies from any of the two formulations made in 1982 may be produced.
(Blank) tells you that the exact momentum and position of a particle can't be known at the same time.
A. The Schrodinger equation
B. Quantum mechanics
C. The uncertainty principle
D. Particle-wave duality
Answer:
The uncertainty principle
Explanation:
Essentially if you measure the momentum of the particle at a given point, then when you go to measure the position it has moved, thus you don't know the position. Vise versa if you measure the position you only capture a still frame of the particle and no information about it's momentum, which will have changed.
Answer: the uncertainly principle
Explanation:
it basically states you can not know both at the same time
which three events occur when earths convection currents move toward each other
Answer:
Option A, Tectonic plates above the currents move toward each other.
Option C, One plate will submerge beneath another plate.
Option D, A convergent boundary is formed at the site of the collision.
Explanation:
The convection currents are the ones responsible for the movement of the tectonic plates, thus shaping the Earth's appearance with their movement, as well with the structures created by the movement. If the convection currents move toward each other, than the tectonic plates are moving toward each other. That will cause collision between the continents, and convergent boundaries will be formed. If the collision is between two or more continental plates, than they will merge, and from the pressure mountain ranges will start to form, but if there an oceanic plate involved as well, than the oceanic plate will be subducting beneath the continental plate or plates.
Answer:
- Tectonic plates above the currents move toward each other;
- One plate will submerge beneath another plate;
- A convergent boundary is formed at the site of the collision;
The convection currents are the ones responsible for the movement of the tectonic plates, thus shaping the Earth's appearance with their movement, as well with the structures created by the movement. If the convection currents move toward each other, than the tectonic plates are moving toward each other. That will cause collision between the continents, and convergent boundaries will be formed. If the collision is between two or more continental plates, than they will merge, and from the pressure mountain ranges will start to form, but if there an oceanic plate involved as well, than the oceanic plate will be subducting beneath the continental plate or plates.
In the reaction Ca + Cl2 → CaCl2, what is the mole ratio of chlorine to calcium chloride?
Select one:
O a. 2:3
O b. 2:1
O c. 1:2
O d. 1:1
PLEASE HELP ME
Answer:
D. 1:1
Explanation:
For every 1 mole of chlorine (Cl₂), there is one mole of calcium chloride (CaCl₂).
So, the mole ratio of chlorine to calcium chloride is 1:1.
Hope this helps. :)
The mole ratio of chlorine to calcium chloride in the given chemical reaction is 1:1.
What is the stoichiometry?Stoichiometry of the reaction gives idea about the relative amount of moles of reactants and products present in the given chemical reaction.
Given chemical reaction is:
Ca + Cl₂ → CaCl₂
From the stoichiometry of the given reaction it is clear that,
1 mole of chlorine = reacts with 1 mole of calcium chloride
So, mole ratio = Chlorine / calcium chloride = 1:1
Hence required mole ratio is 1:1.
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As Danny was pouring cereal for his breakfast, he noticed that the cereal box says that the cereal contains 5 milligrams of iron per serving. Danny decided to perform an experiment to test this claim. He found that the cereal contains 4.6 milligrams of iron per serving. Based on Danny's measurement, the value reported on the label is ( CORRECT OR INCCORECT) because A: (IT IS DIFFERENT FROM THE VALUE DANNY MEASURED) B: (IT IS REORTED TO THE NEAREST MILLIGRAM) C: (IT USES THE SAME UNITS THAT DANNY USED).
Answer:
Correct, because B it is reported to the nearest miligram
Explanation:
4.6 rounded up is 5
Bromine water was added dropwise to test tubes containing aqueous solutions of bromide, chloride, and iodide. lodide was oxidized to iodine; bromide and chloride gave no reaction Arrange Br 2 ,Cl 2 ,I 2 in order of their strength as an oxidizing agent.
Answer:
Cl₂ > Br₂ > I₂
Explanation:
An oxidizing agent gains electron for itself by removing electrons from other reactants during a reaction. Oxidation is the loss of electrons. Chlorine can take electron from bromine and chlorine while bromine can take electron from iodine, therefore chlorine is a more oxidizing agent than bromine and iodine while bromine is a more oxidizing agent than iodine.
Oxidizing ability decreases down the group.
Therefore Cl₂ > Br₂ > I₂
SERE
What type of energy is the sum of an object's potential and kinetic energy?
mechanical energy
electromagnetic energy
chemical energy
thermal enemy
Answer:
Mechanical energy
Answer:
Mechanical Energy
Explanation:
The mechanical energy is the sum of the objects potential energy (energy the object possess due to its position) and its kinetic energy (energy the object possess due to its motion). Adding this two energies together, gives the total mechanical energy.