Answer:
B
Explanation:
a chemical change is making a new substance and physical change with a result in a different state of matter:)
Fossil fuels contribute to about 85% of the total energy produced in the world. What is a direct environmental
consequence of the extensive use of fossil fuels?
Answer:your a poop face
Explanation:
Imagine not knowing the answer
Answer: C
Explanation:
What is the total pressure of mixture in which H2 and CO exerted 31mmHg and 510mmHg respectively
Answer:
Ans: 541 mmHg
Explanation:
given:
H2 = 31mmHg
CO= 510mmHg
get the sum
31+510=541
Balance the following chemical equations:
N2+02___N2O
Answer:
Balance the following chemical equations:
Explanation:
2N2 + O2 → 2N2O
Iodine 131, cesium 137, and strontium 90 are all considered isotopes. What are isotopes?
Answer:
Isotopes are variants of an element, where the number of neutrons is different but its number of protons stay the same.
Explanation:
If the number of protons had changed then it would just be a different element.
Electron number changing simply adds charge to the atom, and doesn't change it or anything.
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Answer:
Isotopes are one of two or more forms of the same chemical element.
Explanation:
Different isotopes of an element have the same number of protons in the nucleus, giving them the same atomic number,but a different number of neutrons giving each element isotope of a different atomic weight.
How many Stars are In the Milky way Galaxy
Answer:
100 thousand million stars
Explanation:
Answer:
100 to 400 billion stars
(a) The absorbance of mixture at 400 nm was 0.40.
Using the standard curve, calculate the
concentration of haemoglobin in g/dl for this female
patient.
Answer:
0.1 g/dl
Explanation:
The standard curve is a graph that relates the absorbance at 400 nm with the concentration of haemoglobin in mg/dl. To obtain the concentration from the absorbance value, we enter in the x-axis (absorbance at 400 nm) with the value 0.40 (the line between 0.2 and 0.6), we extrapolate the line to the curve and read the correspondent value on y-axis (concentration in mg/dl): 100 mg/dl.
So, we convert the concentration from mg/dl to g/dl by dividing into 1000:
100 mg/dl x 1 g/1000 mg = 0.1 g/dl
Therefore, the concentration of haemoglobin of the patient is 0.1 g/dl.
Two reasons why it could be more important to recycle copper than to recycle iron
Answer:
However copper ore is a finite resource and it makes sense to conserve ore by recycling. It is cheaper to recycle old copper than to mine and extract new copper.
Scientists who are investigating what has happened over the years to the people who were exposed to radiation during the 1986 Chernobyl nuclear disaster are conducting what type of study
Answer:
Observational study
Explanation:
An investigation of what happened over the years to the people who were exposed to radiation during the 1986 Chernobyl nuclear disaster would be termed an observational study because it will require observing subjects and finding out if there is a kind of correlating factor in the subjects that could indicate the level of exposure to the nuclear radiation.
There are basically two types of research studies:
1. Observational studies
2. Experimental studies
Observational studies involve just the observation of subjects and trying to find out some correlation factors. This kind of study could be prospective when it deals with what could happen in the future based on certain factors or retrospective when it considers what has already happened. An observational study can be cross-sectional, case-only, case-control, or cohort study.
Experimental studies are also referred to as randomized or controlled trial studies. Here, subjects are grouped and each group receives a different treatment in order to isolate the effect of a particular factor or variable relating to the treatment.
which type of energy is stored as sugars in plant leaves?
1. Chemical
2. Elastic
3. Electrical
4. Mechanical
Answer:
chemical energy
Explanation:
Photosynthesis is the process plants and some algae use to convert light energy to chemical energy stored as sugar within chloroplasts -- the energy factories found in plant cells.
Nitromethane (CH3NO2) is an explosive compound sometimes used as a fuel booster in racecars. What is the formal charge of the nitrogen in a nitromethane molecule?
a. -2
b. -1
c. 0
d. +1
Answer:
Option d. is correct
Explanation:
Nitromethane is an organic compound that can be used as a fuel booster in rockets. Its chemical formula is [tex]CH_3NO_2[/tex].
This compound is produced as a result of reaction of sodium chloroacetate with sodium nitrite in aqueous solution.
The electron-dot structure of a nitromethane molecule shows [tex]+1[/tex] charge on the nitrogen.
Option d. is correct
Write electron configurations for each of the following atoms. Then write the symbol for the most common ion each would form and the electron configuration of that ion.
a) Be
b) CL
c) Se
d) Rb
Answer:
i dont really know this one
Explanation:
Ions can be made by single element or covalently bonded group of elements. The covalently bonded group of elements is called polyatomic ions or polyatomic atoms.
What is Ions?Any species that contain charge whether it is positive charge or negative charge is called ions. The example of polyatomic ions are sulfate, phosphate, nitrate etc.
a)Electronic configuration of Be is 1s² 2s² and the common ion formed by it is Be⁺².
b)Electronic configuration of Cl is [Ne]3S² 3p⁵and the common ion formed by it is Cl⁻.
c)Electronic configuration of Se is [Ar] 3d¹⁰ 4s² 4p⁴ and the common ion formed by it is Se⁻².
d)Electronic configuration of Rb isKr 5s¹ and the common ion formed by it is Rb⁺¹ .
Therefore, Cation is the species that loose electron and attain positive charge while anion is a species which gain electron and attains negative charge
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A patient had for dinner a 3 oz steak, 3 oz salmon, 1 medium apple, and 1 cup of nonfat milk. Using the
chart below, how many total calories did they consume?
Protein
awbohydrate
15
Fal)
0
0
1
126
0
14
22
D
3
4
Food
Apple, 1 medium
Banana, medium
Beel ground, 3oz
Broccoli 304
Carrots, cup
Chicken no skin, 30
Egg, farge
Mik nanta 1 cup
Potato, baked
Salmon 3 02
11
9
2
20
0
3
16
6
10
12
19
10
10
3
23
0
5
16
22
19
Steak 3 0
10
Answer:
1
Explanation:
because there barely eating and there eating protien and healthy foods
KOH (aq) + HNO(little3) (aq) = KNO(little 3) (aq) + H20 (1)
The reaction already balanced
Further explanationEqualization of chemical reactions can be done using variables. Steps in equalizing the reaction equation:
• 1. gives a coefficient on substances involved in the equation of reaction such as a, b, or c, etc.
• 2. make an equation based on the similarity of the number of atoms where the number of atoms = coefficient × index (subscript) between reactant and product
• 3. Select the coefficient of the substance with the most complex chemical formula equal to 1
For gas combustion reaction which is a reaction of hydrocarbons with oxygen produces CO₂ and H₂O (water vapor). can use steps:
Balancing C, H and the last O
Reaction
KOH (aq) + HNO₃ (aq) ⇒ KNO₃ (aq) + H₂0 (l)
give coefficientaKOH (aq) + bHNO₃ (aq) ⇒ KNO₃ (aq) + cH₂0 (l)
K : left = a, right = 1⇒a=1
N : left = b, right =1, b=1
H: left = a, right a+b=2c⇒1+1=2c⇒2=2c⇒c=1
KOH (aq) + HNO₃ (aq) ⇒ KNO₃ (aq) + H₂0 (l)⇒ already balanced
Using the VSEPR model, the molecular geometry of the central atom in ClO3- is:_____.a. bent. b. linear. c. trigonal pyramidal. d. trigonal planar. e. tetrahedral.
Answer:
D
Explanation:
it is trigonal planar, because central atom does not have the lone pairs, equal repulsion
The molecular geometry of the central atom in ClO3- will be triangular pyramidal.
What is VSPER model?The geometry of molecular structures can be predicted using the chemical model known as the valence shell electron pair repulsion hypothesis based on the number of electron pairs surrounding the core atoms of the molecules.
Since ClO3- has a steric number of 4 (one unpaired pair as well as three bonded pairs), can infer that its molecular shape is triangular pyramidal. Its electrical form is tetrahedral, as shown by the Lewis structure above.
Therefore, the correct answer will be option (c).
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Exactly 56 grams of iron is mixed with 156 grams of oxygen. The elements are heated and they react. What best describes which remains after the reaction is complete?
Answer:
Explanation:
The chemical expression for the reaction between iron and oxygen is:
4Fe(s) + 3O₂ (g) [tex]\to[/tex] 2Fe₂O₃ (s)
The number of moles of Fe = mass of Fe/ molecular mass of Fe
The number of moles of Fe = 56 g/ 55.845 g/mol
The number of moles of Fe = 1.002 moles of Fe
The number of moles of oxygen = mass of oxygen/ molecular mass of oxygen
The number of moles of oxygen = 156 g /32 g/mol
The number of moles of oxygen = 4.875 moles of oxygen
Assume that Fe is the limiting reactant, the number of Fe₂O₃ can be calculated as:
moles of Fe₂O₃ = 1.002 mole of Fe × 2 moles of Fe₂O₃/ 4 moles of Fe
moles of Fe₂O₃ = 0.501 mole of Fe₂O₃
Assume that O₂ is the limiting factor, the number of Fe₂O₃ is:
moles of Fe₂O₃ = 4.875 moles of O₂ × 2 moles of Fe₂O₃/ 3 moles of O₂
moles of Fe₂O₃ = 3.25 mole of Fe₂O₃
Thus, after the reaction is complete, Fe and O₂ contain different moles of Fe₂O₃. Only Fe gets consumed in the reaction and it is the limiting factor.
You have a bottle of 18 M H2SO4 in your chemical storage closet. You need to make 2000 mL of a 0.2 M solution. How much of the 18 M sulfuric acid should you need to make this solution (in mL)?
Answer:
20 ml
Explanation:
in which beakers are the particles moving the most slowly
Answer:
A and D
Explanation:
How is the kinetic energy of the particles of a substance affected during a phase change?
Kinetic energy increases during exothermic changes and decreases during endothermic changes.
Kinetic energy decreases during exothermic changes and increases during endothermic changes.
Kinetic energy does not change, but the potential energy does.
Kinetic energy changes in the opposite way that the potential energy changes.
Answer:
its c on edge 2021
Explanation:
During phase change, kinetic energy does not change, but the potential energy does. Therefore, the correct option is option C among all the given options.
What is kinetic energy?Kinetic energy is a type of power that a moving object or particle possesses. An item accumulates kinetic energy when work, which involves the transfer of energy, being done on it by exerting a net force. A moving object and particle has kinetic energy, which relies on both its mass and its rate of motion.
This formula only works for particles traveling at low to moderate speeds; for particles traveling at extremely high speeds, it produces results that are too low. The rules of relativity must be applied when an object's speed approaches the speed of light (3 108 meters per second, about 186,000 miles per second). During phase change, kinetic energy does not change, but the potential energy does.
Therefore, the correct option is option C among all the given options.
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How many moles of water are produced if 5.43 mol PbO2 are consumed?
10.86 moles of water are produced
Further explanationA reaction coefficient is a number in the chemical formula of a substance involved in the reaction equation. The reaction coefficient is useful for equalizing reagents and products.
Reaction
Pb + PbO₂ + 2H₂SO₄ ⇒ 2PbSO₄ + 2H₂O ( a car battery reaction)
From the equation :
mol ratio PbO₂ : H₂O = 1 : 2⇒ 1 mol PbO₂ produces 2 mol H₂O
so for 5.43 mol PbO₂ consumed, mol H₂O :
[tex]\tt 2\times 5.43=10.86~moles[/tex]
Answer:
10.9
Explanation:
edge 2020
Which substance would have the highest melting point, based on electronegativity?
H2O
H2S
H2Te
H2Se
Answer:
H₂O
Explanation:
Based electronegativity, water H₂O will have the higher melting point from the given choices. The binding force between hydrogen and oxygen is greater than for the others.
In group 6, oxygen has the highest electronegativity. It pulls the shared electron closer in the bond. The high electronegativity between hydrogen and oxygen causes the elevated melting point between the two species.Answer:
H2O
Explanation:
hoffe das hilfts
3. Once magnesium (Mg) gives up electron(s) to become an ion, it will become
Answer:
Option B. Cation that is smaller than the original atom.
Explanation:
Magnesium is a divalent element. This implies that magnesium can give up 2 electrons to become an ion (cation) as shown below:
Mg —> Mg²⁺ + 2e¯
Next, we shall write the electronic configuration of magnesium atom (Mg) and magnesium ion (Mg²⁺). This can be written as follow:
Mg (12) = 2, 8, 2
Mg²⁺ (10) = 2, 8
From the above illustration, we can see that the magnesium atom (Mg) has 3 shells while the magnesium ion (Mg²⁺) has 2 shells.
This simply means that the magnesium ion (Mg²⁺) i.e cation is smaller that the original magnesium atom (Mg).
A chemistry student conducted several different procedures. Which of the following procedures best demonstrates the law of conservation of mass?
O using filter paper to separate 2 grams of solid powder from 10 grams of water
O burning 2 kilograms of wood from a pine tree leaves 0.4 kilogram of ash and soot
O evaporating sugar water leaves 5 grams of sugar and turns the water into water vapor
O combining 2 grams of copper and 4 grams of sulfur to make 6 grams of copper sulfate
Answer:
combining 2 grams of copper and 4 grams of sulfur to make 6 grams of copper sulfate
Explanation:
The Law of Conservation of Mass states that matter cannot be created or destroyed in chemical reactions. It posits that the mass of a substance remains unchanged after undergoing a chemical process.
Therefore, according to the question, the procedure that best demonstrates the law of conservation of mass after the chemistry student conducted different procedures is option D.
This is because, the mass of copper and sulfate did not change but merely combined to form a compound.
A graduated cylinder initially has 32.5 mL of water in it. After a 75.0 g piece of lead (Pb) is added to the graduated cylinder, the water level rises to the 39.1 mL mark. What is the the volume of the piece of lead.
Answer:
39.1-32.5 and you will find your answer it always like that, you subtract your starting point from your ending point
Explanation:
The volume of the piece of lead is 6.6 mL
From the question given above, the following data were obtained:
Volume of water = 32.5 mLMass of lead (Pb) = 75 gVolume of water + Lead = 39.1 mLVolume of lead =?The volume of the lead can be obtained as follow:
Volume of lead = (Volume of water + Lead) – (Volume of water)
Volume of lead = 39.1 – 32.5
Volume of lead = 6.6 mL
Therefore the volume of the lead is 6.6 mL
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Using a density of 1.0 g/mL for the water added and adding in the mass of the lithium nitrate, what is the total mass of the solution?
Answer:
The total mass of the solution = 99.7 g
Note: The question is incomplete. The complete question is given below:
A "coffee-cup" calorimetry experiment is run for the dissolution of 2.5 g of lithium nitrate placed into 97.2 mL of water. The temperature of the solution is initially at 23.5oC. After the reaction takes place, the temperature of the solution is 28.3 oC.
1. Using a density of 1.0 g/mL for the water added and adding in the mass of the lithium nitrate, what is the total mass of the solution and solid?
Explanation:
mass = density * volume
density of water = 1.0 g/mL; volume of water = 97.2 mL
mass of water = 1.0 g/L * 97.2 mL
mass of water = 97.2 g
mass of lithium nitrate = 2.5 g
A solution is made by dissolving a solute (usually solid) in a solvent (usually a liquid). The solute in this reaction is lithium nitrate and the solvent is water.
Total mass of solution = mass of water + mass of lithium nitrate
Total mass of solution = 97.2 g + 2.5 g = 99.7 g
Therefore, total mass of the solution = 99.7 g
The total mass of the solution of lithium nitrate solution has been 99.7 grams.
Density can be defined as the mass of the solute per unit volume. The density can be expressed as g/ml or kg/L.
The mass of given Lithium nitrate = 2.5 grams.
The mass of water can be given as:
Density = [tex]\rm \dfrac{Mass}{Volume}[/tex]
Volume of water = 97.2 ml.
The total mass of solution:
Mass of water = Density [tex]\times[/tex] Volume
Mass of water = 1 [tex]\times[/tex] 97.2 grams
Mass of water = 97.2 grams
The total mass = Mass of lithium nitrate + mass of water
= 2.5 + 97.2 grams
= 99.7 grams.
The total mass of the solution of lithium nitrate solution has been 99.7 grams.
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Which of the following is true regarding the atoms involved in a chemical reaction?
A container holds 3.41×10−3mol of carbon dioxide (CO2). After the addition of 8.41×10−4mol of carbon dioxide, the volume of the container increases to 95.2mL, with the temperature and pressure remaining constant. What was the initial volume of the container?
Answer:
76.366
Explanation:
Knewton answer is 76.4
Answer:
76.4mL
Explanation:
First, calculate the final number of moles of carbon dioxide (n2) in the container.
n2 = n1+n added = 3.41×(10^-3) mol+8.41×(10^-4) mol = 4.25×(10^-3) mol
Rearrange Avogadro's law to solve for V1.
V1 =(V2×n1)/n2
Substitute in the known values for n1, V2, and n2.
V1 = (95.2mL×(3.41×10^-3 mol))/(4.25×(10^-3) mol)=76.4mL
So the initial volume is 76.4mL.
Which of the following covalent bonds is the most polar (i.e., highest percent ionic character)?
A) Al I
B) Si I
C) Al Cl
D) Si Cl
E) Si P
Answer:
answer d is correct that works
PLEASE HURRY WILL GIVE BRAINLEST IF ANSWERED CORRECTLY
which separation method would be most successful in separating the components of a homogeneous mixture
screening
evaporation
centrifugation
magnetic separation
Answer:
Evaporation is a technique used to separate out homogeneous mixtures where there is one or more dissolved salts.
Explanation:
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Answer:
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Explanation:
PLS HELP 35 POINTS I WILL GIVE BRAINEST
Answer:
Just count all the different elements like what elemets are in there and you have to identify the number of elemenst
Explanation:
for example H20 and a chemical for example thats two so you identofy which elelments are in there doesnt matter if thered multiple of it all its asking is what id the number of elemts there meaning like one or 2 mayne six different elements