A. A catalyst!!!
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Why do X-Ray technicians stand behind a shield when giving X-Rays to patients?
a.because large doses of X-Rays cause blindness
b.because they can more accurately see the patient's bones
c.because they need to protect themselves from patient disease
d.because large doses of X-Rays are known to cause cell damage and cancers
Which of these is an example of calcium carbonate? diamond graphite shelles of snails water
The shells of snails is an example of calcium carbonate. option C is correct.
What are shells?The shells are made up of calcium carbonate (CaCO3) compounds to protect the eggs or the embryo inside the egg or the soft body of the organism. the main purpose is to protect the body inside the shell from the harsh environment which can damage the body.
The eggshell of snail shell can be used as fillers in the polymer industries and it is the main source of calcium carbonate by crushing the shells we obtain it in powder form it is much rich in calcium.
The main function of the shell is to protect the body inside from the outer environment and for the growth of the body.
Therefore, the shells of snails are an example of calcium carbonate. option C is correct.
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How much heat (in kj) is released when 3.600 mol naoh(s) is dissolved in water? (the molar heat of solution of naoh is â445.1 kj/mol.)?
Answer : The amount of heat released is, -1602.36 KJ
Explanation : Given,
Moles of NaOH = 3.600 mole
Molar heat of solution of NaOH = -445.1 KJ/mole
Now we have to calculate the amount of heat released.
As, 1 mole of NaOH is dissolved in water then heat released = - 445.1 KJ
So, 3.600 mole of NaOH is dissolved in water then heat released = [tex]-445.1\times 3.600=-1602.36KJ[/tex]
Therefore, the amount of heat released is, -1602.36 KJ
What mass of sucrose, c12h22o11, is needed to make 500.0 ml of 0.200 m solution?
Answer: The mass of sucrose is 34.23 g
Explanation:
Molarity is defined as the number of moles present in one liter of solution.
Mathematically,
[tex]\text{Molarity of the solution}=\frac{\text{Moles of solute}}{\text{Volume of solution (in L)}}[/tex]
Or,
[tex]\text{Molarity of the solution}=\frac{\text{Mass of solute}\times 1000}{\text{Molar mass of solute}\times \text{Volume of solution (in mL)}}[/tex]
We are given:
Molarity of solution = 0.200 M
Molar mass of sucrose = 342.3 g/mol
Volume of solution = 500 mL
Mass of sucrose = ? g
Putting values in above equation, we get:
[tex]0.200mol/L=\frac{\text{Mass of sucrose}\times 1000}{342.3g/mol\times 500mL}\\\\\text{Mass of sucrose}=34.23g[/tex]
Hence, the mass of sucrose is 34.23 g
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Chemistry B Semester Final
1. Particles in a gas are best described as ____. (1 point)
• slow-moving, kinetic, hard spheres
• small, hard spheres with insignificant volumes
2. How does the atmospheric pressure at altitudes below sea level compare with atmospheric pressure at sea level? (1 point)
• The atmospheric pressure below sea level is higher.
The weakest hydrogen line stars are classified as:
Class A
Class M
Class Q
Class Z
Calculate the molecular mass of Carbon monoxide (CO) by adding the atomic mass of carbon and the atomic mass of oxygen
The molecular mass of Carbon monoxide (CO) is 28.01 g/mol, which is the sum of the atomic mass of carbon (12.01 g/mol) and oxygen (16.00 g/mol).
The question is asking to calculate the molecular mass of Carbon monoxide (CO). To find the molecular mass, you need to add the atomic mass of carbon (C) and the atomic mass of oxygen (O).
Using the standard atomic weights for these elements, carbon has an atomic mass of approximately 12.01 g/mol and oxygen has an atomic mass of about 16.00 g/mol.
So, the molecular mass of CO would be:
12.01 g/mol (Carbon) + 16.00 g/mol (Oxygen) = 28.01 g/mol (Carbon monoxide)
The substance that works as a reactant in an enzyme catalyzed reaction is called the
if a material is ductile, it is most likely a __________
Answer:
It is known that metals are malleable and ductile
so your answer would be metal
Explanation:
It is known that metals are malleable and ductile. Whereas non-metals are neither malleable nor ductile. On the other hand, metalloids are the elements which contain properties similar to both metals and non-metals.
A student crushes some calcium supplement tablets and dissolves them in water. The resulting solution feels slippery and has a slightly bitter taste. Are the supplement tablets most likely to be acids or bases?
Answer:
bases
Explanation:
Which compound is least soluble in water at 60 degrees Celsius
Is mercury in a thermometer a pure substance or a mixture?
Mercury, as it is present in a thermometer, is classified as a pure substance. It's an element denoted by Hg on the periodic table with a constant composition and properties.
Explanation:The mercury that we find in a thermometer is considered a pure substance rather than a mixture. A pure substance is a form of matter that has a constant composition and properties that are definite throughout the sample. It includes elements and compounds.
Mercury, denoted as Hg on the periodic table, is an element. Therefore, it doesn't consist of different substances mixed together. Its properties, like boiling point and density, remain constant.
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What is incorrect about the atomic orbital arrangement of electrons in this model? How should they be arranged?
NaBr + CaF2 → NaF + CaBr2 What coefficients are needed to balance the chemical equation? A) 1,1,1,1 B) 1,2,1,2 C) 1,2,2,1 D) 2,1,2,1
The correct answer is the D which 2,1,2,1.
Explanation:In a balanced chemical equation, the number of particular atom on the right side of the equation is equal to the number of that atom on the left side of the equation.As in the left side of the equation, there are 2 F atom and 1 Br. While on the right side there are 1 F and 2 Br. S for the balancing, we will put coefficient to the equation.And the equation will be:2NaBr + CaF2 → 2NaF + CaBr2
The theoretical yield for a reaction is 55.9 g LiCl. The actual yield is 24.6 g LiCl. What is the percent yield of the reaction?
Question options:
227%
44%
25%
56%
Which of the following is the best description of a gaseous substance?
The best description of a gaseous substance among the given options is It has no definite shape or volume, and will expand indefinitely. The correct option is an option (c).
Gaseous substances do not have a definite shape or volume. They take shape and fill the entire space of the container they are in. They can expand indefinitely to occupy any available space. This description accurately represents the characteristics of a gaseous substance.
Therefore, It has no definite shape or volume and will expand indefinitely. The correct option is an option (c).
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The complete question is:
Which of the following is the best description of a gaseous substance?
It has no shape of its own but has a definite volume.
It has no definite shape or volume and will expand indefinitely.
It holds its shape without outside restraint.
It is the result of a chemical reaction involving two or more elements.
Final answer:
A gaseous substance is best described as having no definite shape or volume, expanding to fill the volume of any container it is in.
Explanation:
The best description of a gaseous substance is that it has no definite shape or volume, and will expand indefinitely to fill any container. Unlike solids that hold their shape without outside restraint, and liquids that have a definite volume but take the shape of their container, gases are characterized by particles that move about randomly in space with enough energy to completely overcome intermolecular interactions. This significant characteristic delineates a gas from other phases of matter, as it occupies the entire space available, regardless of the size of the container.
if 0.582 moles of zinc reacts with excess lead(IV) sulfate how many grams are zinc sulfate would be produced? can someone help me please?,
Due to the Earth's shape and orientation, areas near the equator receive the greatest amount of energy from the Sun. Ocean currents
A. move only away from the equator as a result.
B. help to distribute this energy by warming other regions of the globe.
C. move only toward the equator as a result.
D. keep this energy concentrated in one region of the globe.
B. help to distribute this energy by warming other regions of the globe.
Welcome.
Areas near the equator receive the greatest amount of energy from the Sun because Ocean currents help in distributing this energy by warming up other regions of the globe. Thus, the correct option is B.
What is the effect of Ocean currents?Ocean currents including the ocean conveyor belt play an important role in the determination of how the ocean distributes heat energy throughout the planet Earth, thereby regulating and stabilizing the climate patterns in different regions of the planet.
Warm current moves away from the equator towards the poles whereas the cold currents concurrently move towards the equator. This process of movement of current waves is known as thermohaline circulation. The cold currents due to their higher density move in the great depth of the oceans while the warmer currents are on the surface due to their relatively lower density.
Therefore, the correct option is B.
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If 82.3 l of an ideal gas is cooled from 46 degrees calius to -166 what will the volume of the gas become
A buffer contains significant amounts of ammonia and ammonium chloride. part a write an equation showing how this buffer neutralizes added acid (hi).
When a strong acid is added to a buffer containing ammonia and ammonium chloride, the ammonia reacts with the acid, neutralizing it and creating ammonium. The remaining ammonium chloride then contributes additional ammonia to maintain the buffer's pH.
Explanation:The buffer contains both ammonia and ammonium chloride, which represent a weak base and its conjugate acid respectively. When a strong acid like HI is added to the buffer, the following reaction occurs NH3 (ammonia) + HI -> NH4+ (ammonium) + I-. In this reaction, the base component of the buffer (ammonia) reacts with the added acid (HI), neutralizing it and producing its conjugate acid (ammonium). The remaining ammonium chloride in the buffer then helps maintain the pH by releasing more ammonia into the solution.
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In a buffer containing ammonia and ammonium chloride, the ammonia molecules react with hydronium ions from the added acid to form ammonium ions and water, neutralizing the acid.
Explanation:A buffer is a solution that resists dramatic changes in pH and is composed of pairs of solutes, such as a weak acid and a salt derived from that weak acid, or a weak base and a salt of that weak base. In this case, the buffer contains ammonia and ammonium chloride. When an acid, such as HI, is added to the buffer, the ammonia molecules react with the hydronium ions (H3O+) to form ammonium ions (NH4+) and water, effectively neutralizing the added acid.
The equation for this reaction is:
H3O+ (aq) + NH3(aq) → NH4+ (aq)+ H2O(1)
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The following reaction shows the process of rusting. 4Fe + 3O 2 2Fe 2 O 3 This chemical reaction should be classified as _____.
Based on their positions in the periodic table, which of the following elements would you expect to have the highest electronegativity value?
Answer:
Fluorine would likely have the highest electronegativity value.
Explanation:
Which reaction results in the greatest increase in entropy?
A. A → 2B
B. A → B
C. 2A → B
D. 3A → B
The reaction that results in the greatest increase in entropy is [tex]\rm A \rightarrow 2B[/tex]. The correct answer is option A.
Entropy is a measure of the disorder or randomness of a system. The greater the number of particles in a system, the greater the entropy. A reaction that produces more particles will result in an increase in entropy.
In reaction [tex]\rm A \rightarrow 2B[/tex], one molecule of A produces two molecules of B. This means that the number of particles in the system has increased, resulting in a greater degree of disorder or randomness and a higher entropy.Therefore, option A. [tex]\rm A \rightarrow 2B[/tex] results in the greatest increase in entropy because it produces more particles, which results in a greater degree of disorder or randomness and a higher entropy.
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What is the maximum amount of kcl that can dissolve in 200 g of water? (the solubility of kcl is 34 g/100 g h2o at 20°c.)?
Answer:
68 grams is the maximum amount of KCl that can be dissolve in 200 g of water.
Explanation:
Let the maximum amount of KCl dissolved in water be x
Solubility of KCl in water = 34g /100 g
This means that 34 g of KCl can be dissolved in 100 g of water at 20°C
Maximum amount of KCl dissolved in 1 g of water = [tex]\frac{34}{100} g[/tex]
Maximum amount of KCl dessolbved in 200 g of water :
[tex]\frac{34}{100}\times 200=68 g[/tex]
68 grams is the maximum amount of KCl that can be dissolve in 200 g of water.
How many grams of co2 are in 6 mol of the compound and the units?
What is the ratio of Fe3+ ions to O2- ions in a neutral compound?
1:2
2:1
2:3
3:2,
An internal combustion engine relies primarily on the efficient production of energy by the combination of oxygen (02) and gasoline (assume this is primarily octane, C8H18). Write the chemical equation for this reaction and derive the exact ratio of oxygen to octane for 100% efficiency.
How many grams of n2f4 can be produced from 225g f2?
How is platinum used to help regulate the release of harmful gases from cars?
Answer:
Platinum is used as a catalytic converter
Explanation:
At present, internal combustion vehicles are equipped with an element called catalytic converter, which is one of the most important components for the control of emissions of polluting gases resulting from combustion produced by engines. Its main function is to transform the polluting gases resulting from the burning of fuel into other gases that are more environmentally friendly. This element is located under the vehicle along the exhaust system pipe after the oxygen sensor.
There are different types of catalytic converters, but modern vehicles are equipped with three-way catalytic converters, referring to the three kinds of pollutant gases that must be reduced (CO, HC and NOX). The converter uses two types of catalysts, one of reduction and another of oxidation. Both consist of a ceramic structure covered with normally platinum, rhodium and palladium metal. The main idea was to create a structure that exposes the catalyst surface to the maximum against the flow of exhaust gases, also minimizing the amount of catalyst required since it is very expensive.