Answer:A
Explanation:
A student in a lab holds an iron nail over an open flame, and no reaction occurs. The nail is then filed, creating small pieces of iron shavings. These pieces burn brightly when placed over an open flame.
Which statement accurately identifies one of the changes that occurs as a physical or chemical change?
A. Filing the nail is a chemical change because the composition of the material does not change but the general appearance of the iron does change.
B. Burning the iron filings is a chemical change because the composition of the material does not change but the general appearance of the iron does change.
C. Filing the nail is a physical change because the composition of the material does not change but the general appearance of the iron does change.
D. Burning the iron filings is a physical change because the composition of the material does not change but the general appearance of the iron does change.
Answer:
A - Filing the nail is a physical change because the composition of the material does not change but the general appearance of the iron does change.
Explanation
yeah its just the right answer
The following statement accurately identifies one of the changes that occurs as a physical or chemical change; "Filing the nail is a physical change because the composition of the material does not change but the general appearance of the iron does change."
The most important aspect of chemical change is that the composition of a substance changes when the substance undergoes a chemical change. This is not the case when the substance undergoes a physical change.
After a physical change, the form, size or appearance may change but never in composition.
Hence the appropriate answer is; "Filing the nail is a physical change because the composition of the material does not change but the general appearance of the iron does change."
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Which formula can be used to calculate the molar mass of hydrogen peroxide (H2O2)? (5 points)
Select one:
a.molar mass of H + molar mass of O
b.2 x molar mass of H + molar mass of O
c.molar mass of H + 2 x molar mass of O Incorrect
d.2 x molar mass of H + 2 x molar mass of O
answer: option d (2×molar mass of H +2×molar mass of O
How many magnesium atoms are there in 1.25 mol of magnesium?
Answer:
1.25 x ( 6.02 × 10^23) = 7.525 × 10^23 atoms
Who first proposed the idea of the atom
Answer:
it's John Dalton
Explanation:
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La densidad de aluminio es 2.7 g/cm3, calcula el volumen si su masa es de 300g
Ayuda please!!!!
d = m / V
Density = mass / volume
d (Density aluminio) = 2.7 g/cm³
m (mass) = 300 g
V (volume) = ?
[tex]volume = \frac{mass}{density} \\ \\ \\ v = \frac{m}{d} = \frac{300 \: g}{2.7 \: g/ {cm}^{3} } = 111.1 \: {cm}^{3} [/tex]
I hope I helped you^_^
what is seed reproduction
Answer:
A seed is formed when fertilised ovule divides by mitosis. ... The ovary of the flower develops into the fruit while ovules develop into seeds. The formation of seed completes the process of reproduction in plants. Within the seed, the growing embryo develops and matures.
I hopes it helps you.When 0.60 mol NH 3 is decomposed in a 1 Liter flask at 850 K, the equilibrium concentration of NH3 is measured as 0.12 M. Given that ammonia decomposes according to the reaction
2 NH3(g) ⇌ N2(g) + 3 H2(g),
what is Kc for the reaction?
a. 0.16
b. 12.00
c. 1.44
d. 6.22
e. 0.75
Answer:
in a 1 Liter flask at 850 K, the equilibrium concentration of NH3 is measured as 0.12 M. Given that ammonia decomposes according to the reaction
2 NH3(g) ⇌ N2(g) + 3 H2(g),
what is Kc for the reaction?
a. 0.16
b. 12.00
c. 1.44
d. 6.22
e. 0.75
The response is 12.00 (b). Using the equation Kc = [N2][H2]3/[NH3]2, we can find the equilibrium constant Kc for the reaction 2 NH3(g) N2(g) + 3 H2(g).
What is the equilibrium concentration ?In this instance, the capacity of the flask is 1 litre, and the equilibrium concentration of NH3 is 0.12 M. Therefore, using the reaction's stoichiometry, it is possible to determine the equilibrium concentrations of N2 and H2.
Since 2 moles of NH3 break down into 1 mole of N2 and 3 moles of H2, the equilibrium concentrations of N2 and H2 are 0.06 M and 0.18 M, respectively. As a result, the equilibrium constant Kc = [N2][H2]3/[NH3]2 = (0.06)(0.18)3/0.122 = 12.00 may be computed.
Therefore, b. 12.00 is the right response. You should be aware that the equilibrium constant Kc is a value that is temperature-dependent and is only applicable at the specified temperature. As a result, Kc will have a varied value depending on the temperature. The temperature in this instance is 850 K, and the Kc value is 12.00.
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equilibrium between two isomers a and b (a and b have the same mol. wt) is attained when there is 5% by weight A and by difference, 95% by weight of B. What is the equilibrium constant
The equili constant assuming reaction is from isomer A to isomer B; 19
i.e. A ⇄ B = 19
Given data :
% wt of A = 5
% wt of B = 95
assume the mass of mixture = 100 g
wt of A = 5% of 100 = 5 g
wt of B = 95% of 100 = 95 g
∴ mole of A = 5/M mol, mole of B = 95/M mol ( where M = molar mass )
expressing the equilibrium constant
A ⇄ B
equilibrium constant = [tex]\frac{[B]}{[A]}[/tex] = [tex]\frac{ (95/M) /V}{(5/M)/V}[/tex] where V = volume
∴ Equilibrium constant = 19 assuming process is from A to B
hence the equilibrium constant = 19 assuming reaction process is from A to B
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Please help me thank you
Explanation:
increases then decreases
1.
2 Explain the meaning of each of the following
terms. In your answer include an example to help
with your explanation.
a Expansion.
d Sublimation.
b Contraction.
e Diffusion.
c Physical change. f Random motion.
a Nar
b Na
c Na
sol
d De
so
Answer:
a. Expansion: the spatial dilation of a material that occurs upon changes in its composition. (an increase in number or amount to become larger in size.)
E.g- in a thermometer, when it gets hotter, the liquid inside them expands and rises up the tube.
b. Sublimation: the process in which a solid changes directly into a liquid.
E.g- dry ice, solid iodine and ammonium salts.
when the above solids are heated, only particles which are found on the surface of the solid have enough energy to break all forces of attraction and form a gas.
c. Contraction: it is the opposite of expansion. when a liquid is cooled the particles slow down and contract.
E.g- when a thermometer is taken out of your mouth, it contracts and the liquid inside falls back to the bottom.
f. Random Motion: motion in which the particle moves in a zig-zag manner and not in a straight line. The kinetic particle theory states that matter is made up of particles which are in constant random motion,
Explanation:
How will a decrease in the concentration of a reactant affect a chemical reaction?
Answer:
When the concentrations of the reactants are raised, the reaction proceeds more quickly. ... When solids and liquids react, increasing the surface area of the solid will increase the reaction rate. A decrease in particle size causes an increase in the .
Water can act as both an acid and a base in an ionization reaction to form (H) and OH ions.
What is this phenomenon called?
Question 4 (1 point)
If you read a graph and saw the values of the motorcycle decreasing over time, this
graph would show a
positive correlation
positive answer
negative correlation
negative answer
From the options listed The graph would show a negative correlation ( C )
Correlation is used to express the relationship between two or more variables. correlation can be measured into four ( 4 ) in statistics :
Pearson correlationKendall rank correlationSpearman correlationPoint-Biserial correlationBut Generally correlation is categorized as either a positive or a negative correlation.
In a negative correlation the variables are inversely proportional to each other while in a positive correlation the variables are directly proportional to each other.
Note : an inverse proportion simply means that an increase in value of one variable = decrease in value of the other and vice versa
hence the graph would show a negative correlation given that the the values of the motorcycle decreases with increase in time.
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11) Calcium Chloride, CaCl2, can be used instead of road salt to melt the ice on roads during the winter. To determine how much calcium chloride had been used on a nearby road, a student took a sample of slush to analyze. The sample had a mass of 23.47g. When the solution was evaporated, the residue had a mass of 4.58g (assume that no other solutes were present).
a) What was the mass/mass percent of calcium chloride in the slush
b) How many grams of calcium chloride were present in 100g solution?
Answer:
What is that? I do not understand
The sun is ____star
The sun is a star.
If you were talking about that
the sun is a Star...............
Answer!! 50 points
Which statement describes the properties of lanthanoids and actinoids?(1 point)
A. They are malleable and lustrous, and they tend to conduct both electricity and thermal energy.
B. They are brittle and dull, and they tend to conduct both electricity and thermal energy.
C. They are brittle and dull, and they tend to be poor conductors of both electricity and thermal energy.
D. They are malleable and lustrous, and they tend to be poor conductors of both electricity and thermal energy.
Answer:
a i j took test and c was wrong
Explanation:
Answer:
the answer is a. c is wrong
Explanation:
Nonmetallic materials that are strong, brittle, resistant to heat and attack by chemicals, and are typically made from clay are known as:________
Define the terms octet rule.
Answer:
The octet rule is a chemical rule of thumb that reflects the theory that main-group elements tend to bond in such a way that each atom has eight electrons in its valence shell, giving it the same electronic configuration as a noble gas.
1. How many pounds does 2.00 kg weigh?
I think is 4.41 the answer of your question
Answer: 4.4lb
Explanation:
A radioactive sample is placed in a closed container. Two days later only one-quarter of the sample is still radioactive. What is the half-life of this sample?
Answer:
2
Explanation:
The sample has halved twice.
1/2 of 1/2 is 1/4, and 1/2 of 1 is 1/2.
50 points!!!
Please help me
In all cases heat flows from a hotter object to a colder object (true/false)
the correct answer will be followed by me and also be marked as the brainliest!
P.S. hv a great Sunday!
Answer
Yes, it's true
In any case or all cases, heat always flow from the hotter object to the colder object
Answer:
In all cases heat flows from a hotter object to a colder object (true/false)
Explanation:
true
Please help me answer that question.
Answer:
(I)
[tex] = (1 + 35.5) \\ = 36.5[/tex]
(II)
[tex] = \{1 + 14 +(16 \times 3) \} \\ = 63[/tex]
(III)
[tex] = \{(2 \times 39) + 12 + (16 \times 3) \} \\ = 138[/tex]
(IV)
[tex] = 23 + 16 + 1 \\ = 40[/tex]
If you fill up a balloon with a small amount of air then set it in direct sunlight you'll see that the balloon expands this expansion is due to an increase in volume which results from...
Answer: An increase in temperature in the balloon.
Explanation: due to an increase in temperature it causes a rise in kinetic energy produced in the balloon thus creating more particle collision thus resulting in expansion in the balloon.
HOPE THIS HELPSS!!!!!!!!!!!
how to calculate the density of a substance
Answer:
DENSITY=mass/volume
Explanation:
Answer:Density, mass of a unit volume of a material substance. The formula for density is d = M/V, where d is density, M is mass, and V is volume. Density is commonly expressed in units of grams per cubic centimetre.
Explanation:
PLS HELP Quick!!!!!!!!!
Answer:
Bailee is incorrect. The mass of objects stay the same but the weight will change.
Explanation:
Mass is how much space something takes up, so that wouldn't change on the moon. The weight however would change because the gravitational pull on the earth is different from that on the moon.
I hope this helps!
Bailee explained that when traveling to the moon. The statement of Bailee is incorrect. The mass of the objects stays the same, but the weight will change. The correct option is B.
What is gravity?Gravity is a force that pulls all objects towards itself. It is present on the earth and in the galaxy. Gravity is the cause of all planets, and the sun and the moon stay in their own places.
The weight of items on the moon is equal to their weight on Earth, according to Bailee, thus he needs only bring a small amount of luggage. The mass is the quantity of matter. The mass never changes, only the weight changes of an object when they are on different planets.
Thus, the correct option is B. The mass of the objects stays the same, but the weight will change.
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In the adjoining figure, the circles with the + sign represent protons and the empty circles represent neutrons. Determine which atoms in the figure are isotopes of each other.
Answer:
2 and 3 explanation in the comments
What is 47.35 dL= mL?
Answer:
4.735 litres
Explanation:
10 dL = 1 litre
47.35 dL = 47.35/10 = 4.735 litres
Which of the following
best describes the cell
wall of a plant cell?
A. sturdy
B. unstable
C. flimsy
D. weak
Answer:
A. Sturdy
Explanation:
Unlike every other answer, the cell wall is the part of the cell that acts as a strong barrier of the cell. In this case, it is sturdy.
All of the following are examples of simple tools except:
A.magnifying glass
B.space telescope
C.pulley
D.lever
Answer:
space telescope I assume
Explanation:
all other tools can be made and used very easily but a telescope took years and years to invent