7. Which of the following is always true when a substance undergoes a
phase change? *
O A. The molecules keep moving at the same average speed.
B. The substance becomes a liquid as it heats up.
C. The melting point of the substance changes.
D. The substance is made up of the same type of molecules.
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What does a particular point on a line of a phase diagram represent ?
Answer:
the line represents the condition where pressure and heat have the same effects.
Answer: C) The melting point of a substance at a specific pressure.
Hydrofluoric acid (HF) can be prepared according to the following equation:
CaF2 + H2SO4 2 HF + CaSO4.
How many grams of HF can be prepared from 75.0 g of H2SO4 and 63.0 g of CaF2?
In the above problem, which reactant is limiting and which is in excess?
Given the balanced equation:
( Reaction type : double replacement)
CaF2 + H2SO4 → CaSO4 + 2HFI
We can determine the number of grams prepared from the quantity of 75.0 H2SO4, and 63.0g of CaF2 by converting these grams to moles per substance.
This can be done by evaluating the atomic mass of each element of the substance, and totaling it to find the molecular mass.
For H2SO4 or hydrogen sulfate it's molecular mass is the sum of the quantity of atomic mass per element. H×2 + S×1 + O×4 = ≈1.01×2 + ≈32.06×1 + ≈16×4 = 2.02 + 32.06 + 64 = 98.08 u (Dalton's or Da) or g / mol.
For CaF2 or calcium fluoride, it's molecular mass adds 1 atomic mass of calcium and 2 atomic masses of fluoride due to the number of atoms.
Ca×1 + F×2 = ≈40.07×1 + ≈19×2 = 40.08 + 38 = 78.07 u (Da or Dalton's) or g / mol.
The limiting reactant in the given balanced reaction is sulphuric acid. The mass of HF produced from 75 g of H₂SO₄ is 30 g.
What is limiting reactant?The limiting reactant in a species is the reactant which is fewer in amount and thus determine the yield of the product.
In the given reaction, one mole of calcium fluoride reacts with one mole of sulphuric acid to give two moles of HF. The molar mass of calcium fluoride CaF₂ is 78 g/mol the weight taken here is 63 g. Thus number of moles is 63/78 = 0.87 moles.
The molar mass of sulphuric acid H₂SO₄ is 100g/mol. The weight taken here is 75 g and thus, number of moles is 75/100 = 0.75 moles. One mole of calcium fluoride need one mole of H₂SO₄ . Thus 0.87 neede 0.87 moles of H₂SO₄ . But here we have only 0.75. Thus it is the limiting reactant.
As per the reaction, one mole or 100 g of H₂SO₄ produce 2 moles or 40 g of HF (molar mass = 20 g/mol). Thus mass of HF produced from 75 g is calculated as follows:
mass of HF = (75 × 40)/100
= 30 g.
Hence, mass of HF produced in this reaction is 30 g.
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Plants and animals can build up or break down rock by increasing weathering, erosion, and
deposition. true or false
Answer:
false
Explanation:
Weathering describes the breaking down or dissolving of rocks and minerals on the surface of the Earth. Water, ice, acids, salts, plants, animals, and changes in temperature are all agents of weathering.
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The answers are here
In which figure does Colin do work?
A. Figure A
B. Figure B
C. Both figures
D. Neither figure
A car is traveling with velocity of 40 m/s and has a mass of 1120 kg. The car has __________ energy.
A. Kinetic
B. Potential
Answer:
A.
Explanation:
The car has kinetic energy.
Which of the following elements would you expect to be ductile and
malleable?
Germanium (Ge)
Argon (Ar)
O O O O
Nitrogen (N)
O Zirconium (Zr)
Answer:
ductile - germanium
mellabe - zirconium
Q3: Fingers and hands pulling, pushing, pressing, or lifting are all examples of applying a
Is it friction gravity motion or force
Answer:
force
Explanation:
because the force
Which of the following is not an example of biased language?
a.
“You are too short to reach that.”
b.
“Are you deaf?”
c.
“Move along, grandpa!”
d.
“I think I’ve been gypped.”
Answer:
I think it is D.
Explanation:
Answer:
b
Explanation:
DESPERATE WILL GIVE BRAILIST AND THANKXS
Which statement is true about a rock layer deposited on top of another rock layer?
A- It is younger than the rock layer below.
B- It is older than the rock layer below.
C- It is the same age as the rock layer below.
D- It is no different than the rock layer below
Hello there!
Your answer is C.
Answer:
The right option is; A. It is younger than the rock layer below.
Explanation:
A rock layer deposited on top of another rock layer is younger than the rock layer below. This is based on the law of superposition which states that in any undeformed sequence of rocks that are laid down in layers, the youngest layer of rock will be on top of the sequence, while the oldest layer will be at the bottom of the sequence.
Josh is washing glasses with soap and water. He is afraid to
carry the glasses because they are slippery. What might he find in the
kitchen that he could use to keep the glasses from being slippery? Explain.
Josh is washing glasses with soap and water. He is afraid to carry the glasses because they are slippery. Josh could dry them with a towel to keep the glasses from being slippery.
What are glasses ?Glasses are visual eyewear that have lenses fixed in a frame that holds them in front of a person's eyes. The frame often has a bridge over the nose and arms that rest over the ears. Glasses are also known as eyeglasses or spectacles.
The term "glasses" likely originated from the word "spyglass," which was originally used to describe "a pair of eyeglasses" that had to be held up to the eyes in order to be fully effective.
Eyeglasses, often known as glasses or spectacles, are lenses that are mounted in frames and worn in front of the eyes to improve vision or to correct astigmatism, myopia, or hyperopia.
Thus, Josh could dry them with a towel to keep the glasses from being slippery.
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what is the half life of the element in the picture
HELP BRAINLIEST
Answer:
6 days
Explanation:
The following data were obtained from the question:
Original amount (N₀) = 100 mg
Amount remaining (N) = 6. 25 mg
Time (t) = 24 days
Half life (t½) =?
Next, we shall determine the decay constant. This can be obtained as follow:
Original amount (N₀) = 100 mg
Amount remaining (N) = 6. 25 mg
Time (t) = 24 days
Decay constant (K) =?
Log (N₀/N) = kt / 2.303
Log (100/6.25) = k × 24 / 2.303
Log 16 = k × 24 / 2.303
1.2041 = k × 24 / 2.303
Cross multiply
k × 24 = 1.2041 × 2.303
Divide both side by 24
K = (1.2041 × 2.303) / 24
K = 0.1155 /day
Finally, we shall determine the half-life of the isotope as follow:
Decay constant (K) = 0.1155 /day
Half life (t½) =?
t½ = 0.693 / K
t½ = 0.693 / 0.1155
t½ = 6 days
Therefore, the half-life of the isotope is 6 days
When Earth is tilted on its axis why does it orbit the sun ?
Answer:
Here
Explanation:
Some assume our planet's changing distance from the sun causes the change in the seasons. That's logical, but not the case for Earth. Instead, Earth has seasons because our planet's axis of rotation is tilted at an angle of 23.5 degrees relative to our orbital plane, that is, the plane of Earth's orbit around the sun
schroedinger thought that electrons
Answer:
In Niels Bohr's theory of the atom, electrons absorb and emit radiation of fixed wavelengths when jumping between fixed orbits around a nucleus. The theory provided a good description of the spectrum created by the hydrogen atom, but needed to be developed to suit more complicated atoms and molecules.
Explanation:
In this unbalanced chemical equation, which element is not conserved?
3LIOH + H3PO4 Li PO4 + 3H20
A. O
B. H
C. P
D. LI
Answer:
LI
Explanation:
There is three Li in the start but One Li after
1. Raw egg to boiled egg.
2. Batter to idli.
3. Wet clothes to dry clothes.
4. Woollen yarn to knitted
sweater.
5. Grain to its flour.
6. Cold water to hot water.
7. Straight string to a coiled string.
8. Bud to flower.
9. Milk to Cheese.
10. Cowdung to biogas.
II. Ice cream to melted ice-cream.
12. Stretched rubber band to
its normal size.
13. Souring of milk.
14. Ripening of a mango.
15. Dissolving sugar in water.
these are reversible or Irreversible, chemical or physical, Natural or manmade, periodic or non periodic,desirable or undesirable?
Answer:
This is man made and natural
I will give brainliest to answer this question right.
Which substance plays a major role in the eutrophication process?
A. ozone
B. salt
C. iron
D.phosphorus
Answer:
The substance is phosphorus or D!
Hope this helps!
When light waves hit ice, most of them bounce off and radiate back into space. Because of this, ice is best described as which kind of surface? reflective absorbent dense rough
The bouncing back of light waves observed when light waves hit ice and most of them bounce off and radiate back into space is called reflection.
What are light waves?Light waves are a form of waves which produces visible sensitization of the eyes
Light waves have properties of waves such as:
reflection refraction diffractioninterference, etc.When light waves hit ice, most of them bounce off and radiate back into space.
This property of light waves is known as reflection.
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When light waves hit ice, most of them bounce off and radiate back into space, hence, ice is best described as a reflective surface.
What is a Reflective surface?A reflective surface is one which can cause incident light to bounce back (reflection).
According to this question, when light waves hit ice, most of them bounce off and radiate back into space. This means that most of the incident light reflects off the ice surface.
Therefore, the ice surface is best described as a reflective surface.
Learn more about reflection at: https://brainly.com/question/8553652
5) If an atom has a positive charge what is it called?
Answer:
An atom that has a negative or positive charge it is called an ion.
Answer:
It''s called a Cation
Explanation:
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The length breadth and thickness of a brick is 18cm 8 cm and 5cm respictively find the area of the widest part of rhe brick
Answer:
144cm²
Explanation:
Given dimensions:
Length x breadth x thickness
18cm x 8cm x 5cm
The widest part of this figure will be the face containing the length and the breadth.
The breadth is the width of the figure;
Area of the widest part = length x breadth = 18cm x 8cm = 144cm
The area of the widest part of the figure is 144cm²
Susana heats up a sample of red crystals. While the sample is being heated,a gas is released and a blue powder is left after heating. Is the sample of red crystals an element or compound?
Answer & Explanation:
Susana's red crystal sample is a compound because it was broken down into a gas and blue powder. It is not an element because elements cannot be broken down into simpler substances by ordinary means, such as heating.
Answer:
Susana's red crystal sample is a compound because it was broken down into a gas and blue powder. It is not an element because elements cannot be broken down into simpler substances by ordinary means, such as heating.
Explanation
Sample response form Edg
Complete the sentence by using the drop-down menus
to choose the words that describe the image most
accurately
To make an omelet, first
the egg and then let
the insides slide
into the bowl.
Answer:
1st one: crack
2nd: carefully
Explanation:
Answer:
Crack and then carefully
Explanation:
I just did it in edgen 2020
How do the alveoli in the lungs move oxygen and nutrients into the bloodstream? 1.Gravity 4.Time 2.Diffusion 5.Pressure 3.Magnetic force
Answer:
2.Diffusion
Explanation:
As we metabolize certain nutrients for the correct functioning of our cells, carbon dioxide is produced as a result. We need oxygen in order to metabolize them, so we need to have a system to incorporate it, and to eliminate the carbon dioxide produced.
This system is provided by the interaction between the respiratory system, which allows the enter of oxygen into the body and gets rid of the carbon dioxide, and the circulatory system, which acts transporting carbon dioxide and oxygen to and from the lungs, respectively.
The surface available for the gaseous exchange is enlarged by the pulmonary alveoli. The alveoli are the terminal aerial spaces of the respiratory system and the structures where the exchange between the air and blood is produced. Each alveolus is surrounded by a net of capillaries, where oxygen is freed from the hemoglobin and moves into the cells by diffusion. Carbon dioxide, diffuses out of the cells into the capillaries, where most of it dissolves in the plasma of the blood.
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A bond in which two atoms share a pair of electrons is a ionic bond or covalent bond or metallic bond?
Answer:
Covalent
Explanation:
Ionic gives or takes electrons
Metallic isn't really a "type" of bond
balance this chemical equation pleaseee
In each case, state whether the forces are balanced or unbalanced. If unbalanced, calculate the net force and describe the direction of the resultant force.
Answer:
Check explanation section.
Explanation:
In order to understand balanced force and unbalanced forces the first law of Newton should be considered as a basic knowledge.
For Balanced forces, there is equal equality in the direction of the forces. In balanced forces, there is no acceleration.
For unbalanced forces, there is acceleration that is go say there is going to be movement. Therefore, net force is equal to unbalanced forces.
(i) Suitcase dropped from a height.
Answer: since there is movement that is acceleration, then the force here is unbalanced force. The resultant force is downwards.towards the greater force direction.
(ii) A bicycle moving with constant velocity on a straight road.
Answer: As the bicycle moves at constant velocity on the straight road the force here is Balanced. Frictional forces balances the forces from the cyclist.
(iii) The rope does not move in a tug of war on applying force at both ends.
Answer: Balanced force.
How many moles of acetaminophen are in a 0.8mL (0.0008L) dose of infants Tylenol
Answer:
0.007 mol
Explanation:
Step 1: Given data
Volume of acetaminophen: 0.8 mL
Step 2: Calculate the mass corresponding to 0.8 mL of acetaminophen
The density of acetaminophen is 1.26 g/mL.
0.8 mL × (1.26 g/mL) = 1 g
Step 3: Calculate the number of moles corresponding to 1 g of acetaminophen
The molar mass of acetaminophen is 151.16 g/mol.
1 g × (1 mol/151.16 g) = 0.007 mol