Answer:
The sun.
Explanation:
Sun is the ultimate source of energy. All living things on the earth using the energy comes from the sunlight.
Plants using sunlight to fuel the process of photosynthesis. Photosynthesis is the process of transforming of water and carbon dioxide to oxygen and glucose. The amount of energy used to drive the photosynthesis process is stored in the glucose molecules.
Organism feed on plants and breaking down the glucose molecules to release the stored energy. The release energy is utilized by the cells present in the organisms.
Autotrophs also have the ability to make their own food, so they are also using the energy from the sun to make their food.
How many valence electrons are in each atom? a. potassium C. magnesium b. carbon d. oxygen
Which of the following reactions had the greatest percent yield?
a.Theoretical yield 52.3 g; actual yield 50.7g
b.Theoretical yield 17.1 g; actual yield 15.7g
c.Theoretical yield 38.8 g; actual yield 36.2 g
d.Theoretical yield 24.6 g; actual yield 22.5 g
Answer:
Option A
Explanation:
As we know
Percent yield is the ratio of actual yield/theoretical yield
a) Percent yield - Theoretical yield 52.3 g; actual yield 50.7g = 0.97 = 97%
b) Percent Yield - Theoretical yield 17.1 g; actual yield 15.7g = 92%
c) Percent Yield - Theoretical yield 38.8 g; actual yield 36.2 g = 93%
d) Percent Yield - Theoretical yield 24.6 g; actual yield 22.5 g = 91%
Hence option A is correct
How many grams of Fe2O3 are needed to produce 51.9 g of CaO?
Answer:
98.8g (3 s.f.)
Explanation:
Use the mole = mass/mr equation to find the moles of CaO, then use the molar ratio to find the moles of Fe2O3, which is the same as CaO, (assuming the ratio is 1:1, as you haven't stated it clearly in the question). Then use the equation and input to find Mass, which is 98.8g to 3 s.f.
i have a quiz yall help
How many moles are in a 18 L tank of nitrogen gas at STP?
Answer:
12
Explanation:
i feel like its 12 because moles are medium sized but are they adult moles or baby moles or growing moles
Mole measure the number of elementary entities of a given substance that are present in a given sample. Therefore, 0.803moles of nitrogen gas are there in a 18 L tank of nitrogen gas at STP.
What is mole?The SI unit of amount of substance in chemistry is mole. The mole is used to measure the quantity or amount of substance. We know one mole of any element contains 6.022×10²³ atoms which is also called Avogadro number.
Mathematically,
number of moles of any ideal gas =given volume ÷Volume occupied by one mole of a ideal gas at STP
Volume occupied by one mole of a ideal gas at STP=22.4L
given volume of nitrogen gas= 18 L
substituting all the given values in the above equation we get,
number of moles of nitrogen gas =18 L ÷22.4L
number of moles of nitrogen gas =0.803moles
Therefore, 0.803moles of nitrogen gas are there in a 18 L tank of nitrogen gas at STP.
To know more about mole, here:
https://brainly.com/question/15209553
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5) Which element has the lowest first ionization energy?*
Li
K
Na
Answer:
K
Explanation:
Ionisation energy is the energy required for electron loss and the higher the occupied energy levels=higher atomic radius=the lower the ionisation energy thus k=2.8.8.1
Na=2.8.1
Li=2.1
how are the messages of the endocrine system moved around the body?
Answer:
Endocrine glands make chemicals called hormones and pass them straight into the bloodstream. Hormones can be thought of as chemical messages. From the blood stream, the hormones communicate with the body by heading towards their target cell to bring about a particular change or effect to that cell.
how many moles of solute are present in a 2 L of a 25M potassium nitrate solution
a. 0.5 moles
b. 2 moles
c. 50 moles
d. 25 moles
I NEED THIS ANSWER ASAP, im taking the quiz right now and i need HELPPP
Answer:
50 moles
Explanation:
took the quiz
If the pressure on a gas at -73°C is doubled but its volume is held constant, what will its final temperature be in degrees Celsius?
Answer:
127°C
Explanation:
This excersise can be solved, with the Charles Gay Lussac law, where the pressure of the gas is modified according to absolute T°.
We convert our value to K → -73°C + 273 = 200 K
The moles are the same, and the volume is also the same:
P₁ / T₁ = P₂ / T₂
But the pressure is doubled so: P₁ / T₁ = 2P₁ / T₂
P₁ / 200K = 2P₁ / T₂
1 /2OOK = (2P₁ / T₂) / P₁
See how's P₁ term is cancelled.
200K⁻¹ = 2/ T₂
T₂ = 2 / 200K⁻¹ → 400K
We convert the T° to C → 400 K - 273 = 127°C
Help!! < PHYSICAL SCIENCE>
If the football indoors had a volume of 5.33 L at 21degrees celsuis, what is the volume of the football outside where the temp is 10C (temp must be in K) MUST SHOW WORK
Answer:
5.13 L
Explanation:
From the question given above, the following data were obtained:
Initial volume (V₁) = 5.33 L
Initial temperature (T₁) = 21 °C
Final temperature (T₂) = 10 °C
Final volume (V₂) =?
Next, we shall convert celsius temperature to Kelvin temperature. This can be obtained as follow:
T(K) = T(°C) + 273
Initial temperature (T₁) = 21 °C
Initial temperature (T₁) = 21 °C + 273
Initial temperature (T₁) = 294 K
Final temperature (T₂) = 10 °C
Final temperature (T₂) = 10 °C + 273
Final temperature (T₂) = 283 K
Finally, we shall determine the final volume. This can be obtained as follow:
Initial volume (V₁) = 5.33 L
Initial temperature (T₁) = 294 K
Final temperature (T₂) = 283 K
Final volume (V₂) =?
V₁/T₁ = V₂/T₂
5.33 / 294 = V₂ / 283
Cross multiply
294 × V₂ = 5.33 × 283
294 × V₂ = 1508.39
Divide both side by 294
V₂ = 1508.39 / 294
V₂ = 5.13 L
Thus, the new volume of the football is 5.13 L
Which statement describes the solar feature shooting off into space labeled C?
An envelope of plasma surrounding the sun
A stream of glowing gas that shoots out from the sun in an arch
A brief eruption of intense high-energy radiation from the sun's surface
A dark spot appearing from time to time on the sun's surface
Answer:
The correct answer is - An envelope of plasma surrounding the sun.
Explanation:
In the provided diagram the C labeled part of the sun is an envelope of plasma surrounding the sun which is called Solar Corona which makes the outermost layer of the atmosphere of the sun. Solar Corona is hotter in comparison to the surface of the sun itself.
Solar Corona is made up of the fourth state of matter known as plasma that has its magnetic field that determined its structural characteristics. Thus, the correct answer is an envelope of plasma surrounding the sun.
Answer:
person above is correct
Explanation:
I took the quiz and got it right.
Which answer choice describes all nonmetals? A. All of the elements of Period 2 in green boxes B. Hydrogen and all of the other elements in orange boxes C. All of the elements of Group 18 in orange boxes D. Hydrogen and all of the elements in blue boxes
Use the Word Correctly in a Sentence
Ion
C4H10+ 02 → CO2 +H2O
balance the equation
Answer:
C4H10 + 502 -> CO2 + 5H20
......
.......
Which term refers to an electrochemical cell that uses a spontaneous redox reaction to produce an electric current?
electrolyte
voltaic cell
electrolytic cell
cathode
0.53g of acetanilide was subjected to kjeldahl determination and the ammonia produced was collected in 50cm3 of 0.50M of h2so4.on dilution 250cm3, the acid was titrated against 25cm3 portion of 0.05M sodium carbonate solution. 13.60 of acid was required for each titration. What is percentage of nitrogen in acetanilide
Answer:
10.57% of N in acetanilide
Explanation:
All nitrogen in the sample is converted in NH₃ in the Kjeldahl determination. The NH₃ reacts with H₂SO₄ as follows:
2NH₃ + H₂SO₄ → 2NH₄⁺ + SO₄²⁻
The acid in excess in titrated with Na₂CO₃ as follows:
Na₂CO₃ + H₂SO₄ → Na₂SO₄ + H₂O + CO₂
To solve this question we must find the moles of sodium carbonate = Moles of H₂SO₄ in excess. The added moles - Moles in excess = Moles of sulfuric acid that reacts:
Moles Na₂CO₃ anf Moles H₂SO₄ in excess:
0.025L * (0.05mol / L) = 1.25x10⁻³ moles Na₂CO₃ / 0.01360L =
0.09191M * 0.250L = 0.0230 moles H₂SO₄ in excess.
Moles H₂SO₄ added:
0.050L * (0.50mol / L) = 0.0250 moles H₂SO₄ added
Moles that react:
0.0250 moles - 0.0230 moles = 0.0020 moles H₂SO₄
Moles of NH₃ = Moles N:
0.0020 moles H₂SO₄ * (2mol NH₃ / 1mol H₂SO₄) = 0.0040 moles NH₃ = Moles N
mass N and mass percent:
0.0040 moles N * (14g / mol) = 0.056gN / 0.53g * 100 =
10.57% of N in acetanilideConsider the redox reaction below. Upper M g (s) plus Pper f e superscript 2 plus (a q) right arrow upper M g superscript 2 plus (a q) plus upper F e (s). Which equation is a half reaction that describes the reduction that is taking place?
Answer: [tex]Fe^{2+}(aq)+2e^-\rightarrow Fe(s)[/tex]
Explanation:
Oxidation reaction is defined as the reaction in which a substance looses its electrons. The oxidation state of the substance increases.
Reduction reaction is defined as the reaction in which a substance gains electrons. The oxidation state of the substance gets reduced.
[tex]Mg(s)+Fe^{2+}(aq)\rightarrow Fe(s)+Mg^{2+}(aq)[/tex]
The oxidation half reaction is:
[tex]Mg(s)\rightarrow Mg^{2+}(aq)+2e^-[/tex]
The reduction half reaction is:
[tex]Fe^{2+}(aq)+2e^-\rightarrow Fe(s)[/tex]
Answer:
A
Explanation:
edge
1)Why do clouds usually form high in the air instead of near Earth's surface?
a) High in the atmosphere is less dense
b) High in the atmosphere contains less oxygen
c) High in the atmosphere is usually cooler
d) High in the atmosphere has less air pressure
please help there is a pic and marking brain list
Answer:
3
Explanation:
Chem. Assignment
I need help...with answers 1-6 thanks
Answer:
1. an educated guess
2. data
3. what changes in experiment
4. what stays the same in both groups
5. the group where nothing changes, normal
6. group with independent variable, what's being tested
1. When _____
are added or removed from an atom, _____
is formed
Answer:
1.) protons or electrons 2.) ion
Explanation:
Name
12. A chemist places a piece of solid magnesium in an aqueous solution of copper (II)
sulfate and notices a reaction. Pieces of solid copper dropped out of the solution as a
precipitate and magnesium sulfate was formed.
a) Give a balanced formula equation (with state symbols) for this reaction (3 marks)
Answer:
Explanation: Mg(s) + CuSO4 (aq) -> Cu(s) + MgSO4 (aq)
1.The water molecule is-
A. Slightly negative near the hydrogen atoms and slightly positive near the oxygen atom
B. Slightly positive in all areas of the molecule
C. Slightly negative near the oxygen atom and slightly positive near the hydrogen atoms
D. The same charge in all areas of the molecule
Answer:
C.
Explanation:
Slightly negative near the oxygen atom and slightly positive near the hydrogen atoms
How do you explain the ability of nonmetals to attract electrons to themselves?
Answer:
When these chemical bonds form, atoms of some elements have a greater ability to attract the valence electrons involved in the bond than other elements. Electronegativity is a measure of the ability of an atom to attract the electrons when the atom is part of a compound. Electronegativity differs from electron affinity because electron affinity
HOPE IT HELPS
Explanation:
Answer:
it is electronegativity and it increases as you move up and to the right on the periodic table and nonmetals are situated to the top right of the periodic table
Explanation:
A concept map is shown.
Which of the following topics best completes the graphic organizer?
A. Physical properties of elements
B. Chemical properties of elements
C. Evidence of a physical change
D. Evidence of a chemical change
Answer:
C Evidence of Physical change
Explanation:
Because Solid forms is a physical change and so are all the other ones
Substances that absorb energy in the form of heat are
A) Exothermic
B) Endothermic
C) Isothermic
Answer:
Substances that absorb energy in the form of heat are
b)endothermic.
hope it helps :)
4. The volume of a gas is 2.5 L when the pressure is at standard pressure (101.325 kPa). What is the
volume of the gas if the pressure decreases to 85 kPa and the temperature of the gas if the pressure is constant?
Answer:
18.32L
Explanation:
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Define pollination, fertilization and photosynthesis process
Explain how to count the number of elements in a compound.
Answer:
Simply identify what elements are in a compound
Explanation:
For example in NaCl we have sodium (Na) and Chlorine (Cl)
In order to do this you would need to recognise the symbols for a certain element: O for oxygen; N for nitrogen; H for hydrogen etc.
is an example of a solution that contains a dissolved substance
Answer:
An aqueous solution is water that contains one or more dissolved substances. The dissolved substances in an aqueous solution may be solids, gases, or other liquids.