Answer:
303.6 mg
Explanation:
Given that:
The lethal dose [tex]LD_{50}[/tex] = 1320 mg/kg
The weight of the rat = 230 g
The lethal dose is the dose of a substance likely to cause death. SO a lethal dose of 50 will cause the death of 50% of the sample of test animals.
Therefore;
The mass of 2-naphthol that would have been ingested by each rat in a sample set of rats in order to kill half the population of rats will be equal to:
[tex]=\dfrac{LD_{50}}{1000} \times wt \ of \ rat[/tex]
[tex]=\dfrac{1320}{1000}\times 230[/tex]
= 303.6 mg
Liquid nitrogen is kept at a temperature of -320 degrees. When liquid nitrogen is heated it quickly boils and turns into a gas. Which pair of pictures represent the change caused by adding heat to liquid nitrogen?
So when something is boiling it is moving faster meaning the molecules are more spread out and not condense like a solid
So the answer is the 2nd set
Are light and other forms of energy are made of atoms
Answer:
yes they are
Explanation:
In a closed system, the total energy before an energy transformation is _______ the total energy after it.
A.
less than
B.
equal to
C.
unrelated to
D.
greater than
In a closed system, the total energy before an energy transformation is greater than the total energy after it.
What is a closed system ?A closed system is a natural physical system that does not permit the movement of matter into or out of the system, while energy transfer is permitted in some situations, such as those found in physics, chemistry, or engineering.
A closed system is one that only allows the flow of energy; it forbids the exchange of matter. The heat can transfer when we boil water with a closed cover, but the matter cannot.
In a closed system, the overall energy is constant. The universe's overall energy is always changing. Mass may be used to store energy. In a closed system, energy may be transformed from one form to another.
Thus, option D is correct.
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How would I find the answer?
Answer:
Kr
Explanation:
The noble gas that is isoelectronic with Br⁻ is krypton.
This is because krypton is the closest noble gas to Br on the periodic table.
Electronic configuration of Bromine is;
2, 8, 18, 7
Br⁻ becomes; 2, 8, 18, 8
Krypton is; 2, 8, 18, 8
Which shows three human body parts in order from the simplest level of organization to the most complex?
red blood cell → nervous system → bone tissue
nervous system → bone tissue → red blood cell
red blood cell → heart tissue → circulatory system
bone tissue → red blood cell → nervous system
Answer:
red blood cell → heart tissue → circulatory system
Explanation:
The levels of organization from the simplest level of organization to the most complex is cell, tissue, organ, organ, organ system, and organism. Red blood cells are cells, heart tissue is tissue in the heart and the circulatory system is an organ system that ensures blood, oxygen, and nutrients are flowing through the body.
Red blood cell → heart tissue → circulatory system shows the three human body parts in order from the simplest level of organization to the most complex.
What is heart?Heart is a muscular organ which is present in most of the animals , it is responsible for pumping blood via the blood vessels to the entire body.The blood which is pumped carries oxygen and nutrients along with it.Along with it on it's way back to heart it carries carbon dioxide to the lungs.
Heart has an approximate size of a closed fist and is present between the lungs in the middle compartment of the chest. It is divided in to for chambers , the upper chambers called atria and lower ones called ventricles.
The wall of the heart is made up of three layers : epicardium,myocardium and endocardium. It pumps blood with a rhythm which is determined by a group of cells which are called the pacemaker cells present in the sinoatrial node.
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In general, atoms that have a high electronegativity have a ____ first ionization energy and a ____ atomic radius.
NEED ASAP
Select one:
a. low, small
b. high, large
c. low, large
d. high, small
Answer:
The correct option is D
Explanation:
Firstly, let's define the periodicity of these terms and then draw conclusion from there.
Ionization energy is the amount of energy required to remove an electron from a gaseous atom in it's ground state. This property increases across a group in the periodic table.
Electronegativity is the measure of the property/tendency of an atom to attract an electron. This property also increases across a period. Thus, elements that have high electronegativity also have a high ionization energy.
Atomic radius is however the distance between the central nucleus to the outermost electron. This property decreases across the period. Thus, as electronegativity and ionization energy increases, atomic radius decreases.
From the above, it can be deduced that the correct option is d
Answer:high,small
Explanation:
I have the same test and I got it right
Solution A is 100 times as acidic as solution B. What is the difference in pH values of solution A and solution B
Answer:
The difference is 2 pH units.
Explanation:
Let's give an arbitrary value to the H⁺ concentration of solution A, [H⁺]ₐ:
[H⁺]ₐ = 0.001 MIf that's the case then the pH of solution A would be:
pHₐ = -log(0.001) = 3----
The H⁺ concentration of solution B ( [H⁺]ₓ ) is 100 higher than that, so:
[H⁺]ₓ = 0.001 * 100 = 0.1 MAnd its pH:
pHₓ = -log(0.1) = 1So the difference in pH values is:
pHₐ - pHₓ = 3 - 1 = 2If a neutral atom has 49 protons, how many electrons does it have?
Iron, an element with the chemical symbol Fe, is an important element. It is used to make steel and is part of the substance that transports oxygen throughout the human body.
Which statement about Fe is supported by the modern atomic theory but not John Dalton’s theory?
A. The element iron is composed of small particles called atoms.
B. The electrons of iron have probable locations in a region of space around the nucleus.
C. Iron atoms combine with other atoms in whole number ratios to form compounds.
D. Chemical reactions that involve iron do not create new atoms of iron.
Answer:
i think its B
Explanation:
Answer:
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Explanation:
Balance the reaction below using the correct coefficient.
__Ag2S --> __Ag + __S8
Answer:
8Ag2S--->16Ag+S8
Explanation:
thats your answer hope it helps
8. ______________ and _____________ are located in the nucleus.
Answer:
protons and neutrons are located in the nucleus.
What creates a weather front?
A weather front is a transition zone between two different air masses at the Earth's surface. Each air mass has unique temperature and humidity characteristics. Often there is turbulence at a front, which is the borderline where two different air masses come together. The turbulence can cause clouds and storms.
Which of the following statement best defines matter?
Answer:matter is anything has mass and take up space
Explanation:
A(n)___ is the smallest neutral unit of two or more atoms held together by a covalent bond?
Answer:
A(n)___ is the smallest neutral unit of two or more atoms held together by a covalent bond?
=>MOLECULE
Is NH4CIO3 ionic or ionic using the stock system or molecular
Answer:
I believe it would be ionic using the stock system.
Explanation:
The only difference is the size of cations, Cs+ being larger than Na+ and hence Na+ will have more polarising power than Cs+ and hence NaCl will be more covalent than CsCl or in other words CsCl will be more ionic than NaCl.
How many molecules are in Na2CrO4
Answer:
It is 161.97324 g/mol
1 molecule
Aluminum has a density of 2.70 g/mL. Calculate the mass (in grams) of a piece of aluminum having a volume of 238 mL .
Answer:
mass in gram = 642.6 g
Explanation:
Given data:
Density of aluminum = 2.70 g/mL
Volume of aluminum = 238 mL
Mass in gram = ?
Solution:
Density:
Density is equal to the mass of substance divided by its volume. The symbol used for density is called rho. It is represented by ρ. However letter D can also be used to represent the density.
SI unit of density is Kg/m3.
Other units are given below,
g/cm3, g/mL , kg/L
Formula:
d =m/v
d = density
m=mass
V=volume
Now we will put the values in formula.
2.70 g/mL = m/ 238 mL
m = 2.70 g/mL × 238 mL
m = 642.6 g
6 List What are two advantages and two
limitations of physical models?
Plz help
Answer:
Physical models can represent objects or systems that are too small, too big, or too far away to study. They are way easier, cheaper, and safer to work with or use when compared to the real objects that they represent.
Explanation:
During winter, you can sometimes ice skate outdoors on a frozen lake. Why can’t you ice skate on a lake when it is not frozen?
Answer:
Generally the ice should be more than 4 inches thick to skate on it safely. However, the ice thickness is not always even and there can be thin spots, especially near springs or near river inlets or outlets. Most lakes and ponds don't completely freeze because the ice (and eventually snow) on the surface acts to insulate the water below. Our winters aren't long or cold enough to completely freeze most local water bodies. This process of lakes turning over is critically important to the life in the lake.
Explanation:
Help in history class please Thnks
Answer:
C) Foreign relations and war powers
If a reaction generated 3.5 g of H2O how many moles of water were formed?
Answer:
0.19 mol H₂O
General Formulas and Concepts:
Chem
Reading a Periodic TableUsing Dimensional AnalysisExplanation:
Step 1: Define
Given: 3.5 g H₂O from RxN
Step 2: Define conversions
Molar Mass of H - 1.01 g/mol
Molar Mass of O - 16.00 g/mol
Molar Mass of H₂O - 2(1.01) + 16.00 = 18.02 g/mol
Step 3: Convert
[tex]3.5 \ g \ H_2O(\frac{1 \ mol \ H_2O}{18.02 \ g \ H_2O} )[/tex] = 0.194229 mol H₂O
Step 4: Check
We are given 2 sig figs. Follow sig fig rules.
0.194229 mol H₂O ≈ 0.19 mol H₂O
What is the name of the groups that contain Iron(Fe) and Gold(Au)?
Answer:
Transition Metals
Explanation:
Answer:
Group 8 & 11
Explanation:
Transition Metals
While performing a neutralization reaction, Jonna added 22.63 mL of 0.142 M H2SO4 to 46.21 mL of 0.304 M KOH. How many moles of OH- are unreacted in the solution after the neutralization is complete?
Answer:
7.623 x 10⁻³ mol OH⁻
Explanation:
The reaction that takes place is:
H₂SO₄ + 2KOH → K₂SO₄ + 2H₂ONow we calculate how many moles of each reagent were added:
H₂SO₄ ⇒ 22.63 mL * 0.142 M = 3.213 mmol H₂SO₄KOH ⇒ 46.21 mL * 0.304 M = 14.05 mmol KOHWe calculate how many OH⁻ moles reacted with H₂SO₄:
3.213 mmol H₂SO₄ * [tex]\frac{2mmolOH^-}{1mmolH_2SO_4}[/tex] = 6.427 mmol OH⁻Finally we substract the OH⁻ moles that reacted from the added ammount of OH⁻ moles:
14.05 mmol KOH - 6.427 mmol OH⁻ = 7.623 mmol OH⁻7.623 mmol / 1000 = 7.623 x 10⁻³ mol OH⁻The number of moles of OH⁻ that are unreacted in the solution after the neutralization reaction is complete is 0.00770 moles OR 7.70×10⁻³ moles
First, we will write a balanced chemical equation for the neutralization reaction
The balanced chemical equation for the neutralization reaction is
H₂SO₄ + 2KOH → K₂SO₄ + 2H₂O
This means
1 mole of H₂SO₄ reacts with 2 moles of KOH to give 1 mole of K₂SO₄ and 2 moles of H₂O
To determine the number of moles of OH⁻ that are unreacted after the neutralization is complete,
We will determine the number of moles of KOH remaining in the solution after the neutralization reaction is complete
First, we will determine the number of moles of each reactant present
For H₂SO₄Volume = 22.36 mL = 0.02236 L
Concentration = 0.142 M
From the formula,
Number of moles = Concentration × Volume
∴ Number of moles of H₂SO₄ = 0.142 × 0.02236
Number of moles of H₂SO₄ = 0.00317512 moles
For KOHVolume = 46.21 mL = 0.04621 L
Concentration = 0.304 M
∴ Number of moles of KOH = 0.304 × 0.04621
Number of moles of KOH = 0.01404784 moles
(NOTE: This is equal to the number of moles of OH⁻ at the beginning of the reaction)
From the equation of reaction, we have that
1 mole of H₂SO₄ will neutralize 2 moles KOH
Therefore,
0.00317512 moles of H₂SO₄ will neutralize 2×0.00317512 moles KOH
2×0.00317512 = 0.00635024 moles
This means only 0.00635024 moles of KOH reacted
(NOTE: This is equal to the number of moles of OH⁻ that reacted)
Now, for the number of moles of unreacted OH⁻
Number of moles of unreacted OH⁻ = Total number of moles OH⁻ at the beginning of the reaction - Number of moles of OH⁻ that reacted
∴ Number of moles of unreacted OH⁻ = 0.01404784 moles - 0.00635024 moles
Number of moles of unreacted OH⁻ = 0.0076976 moles
Number of moles of unreacted OH⁻ ≅ 0.00770 moles OR 7.70×10⁻³ moles
Hence, the number of moles of OH⁻ that are unreacted in the solution after the neutralization is complete is 0.00770 moles OR 7.70×10⁻³ moles
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A chemist prepares a solution of magnesium fluoride MgF2 by measuring out 0.0113μmol of magnesium fluoride into a 450.mL volumetric flask and filling the flask to the mark with water. Calculate the concentration in /mmolL of the chemist's magnesium fluoride solution. Round your answer to 3 significant digits.
Answer:
2.51x10⁻⁵ mmol MgF2/L
Explanation:
To find the concentration in mmol / L we need to convert μmol to mmol (1000μmol / 1mmol) and mL to Liters (1000mL / 1L) as follows:
μmol MgF2:
0.0113μmol MgF2 * (1mmol / 1000μmol) = 1.13x10⁻⁵ mmol MgF2
Liters solution:
450mL * (1L / 1000mL) = 0.450L
Concentration in mmol/L:
1.13x10⁻⁵ mmol MgF2 / 0.450L =
2.51x10⁻⁵ mmol MgF2/L1. When waves go from one place to another, they transport
A. amplitude
C. frequency
B. wavelength
D. energy
Which of the following statement best defines matter?
Will the boiling point of water be higher or lower in the maintains, where the altitude is high, and the pressure is low ?
What is the chemical name of the compound NH4SCN?
Its called "Ammonium thiocyanate" Have a great day!! <3
Answer:
it is called Ammonium Thiocyanate or Thiourea
Explanation:
it is made made up of 2 nitrogen atoms, 4 hydrogen atoms, 1 sulfur atom and 1 carbon atom. stay safe and have a great day! TPWK
The noble gases can be found in group/period ____
Answer:
group 18
Explanation:
The noble gases (Group 18) are located in the far right of the periodic table and were previously referred to as the "inert gases" due to the fact that their filled valence shells (octets) make them extremely nonreactive
Answer:group 18
Explanation
name the intermolecular force between Ne in liquid
Answer:
Intermolecular forces in liquid are
Intermolecular forces are electrostatic in nature and include van der Waals forces and hydrogen bonds. Molecules in liquids are held to other molecules by intermolecular interactions, which are weaker than the intramolecular interactions that hold the atoms together within molecules and polyatomic ions.
Answer:
it is found in the halogen ,the no le gases and in other non polar molecules such as co2 and methane. Landon dispersion force are part of the Vander waals force or weak intermolecular attraction