Answer:
true
Explanation:
Which of these two statements meets the criteria of a
scientific hypothesis?
a. Acids turn red litmus paper blue.
b. All life in the universe exists on Earth.
Litmus paper can't accurately determine how acidic or alkaline a substance is because the results are qualitative (observable), not quantitative (measurable).
What is Litmus paper?
Mechanism. It contains a mild acid, red litmus. The hydrogen ions interact with the additional base when it is in contact with a basic substance.
The moist red litmus paper turns blue when placed in an alkaline solution because the conjugate base that is created from the litmus acid has a blue.
Chemistry uses a litmus or litmus paper test to detect if a solution is basic or acidic. Some lichen species are the source of litmus.
When exposed to an acid, litmus will turn red; when exposed to a base, it will turn blue.
Therefore, statements a meets the criteria of a scientific hypothesis.
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A material has a density of 8.9 g per c m cubed. You have three cubic centimeters of the substance. What is the material's mass in grams?
Question 25 options:
3.0 g
0.3 g
27 g
5.9 g
Explanation:
density can be calculated using the following rule: density=mass/volume
therefore,
mass = density x volume
we have density 8.9gm/cm³ and volume=3cm³ substituting in the above equation, we can calculate the mass as follows:
mass = 8.9 x 3 = 26.7 grams,
Approx 27 grams
27 g is your answer
Answer:
density =8.9g/cm³
Explanation:
1cm³=8.9g
3cm³=8.9×3=26.7g
Cl2 reacts with the element Sr to form an ionic compound. Based on periodic properties, identify a molecule, X2, that is likely to react with Sr in a way similar to how Cl2 reacts with Sr. Justify your choice.
Answer:
Explanation:
Scrontium (Sr) is a metal in group 2 of the periodic table. While chlorine (Cl) is a nonmetal (halogen) in group 7 of the periodic table. Generally, elements in this two groups of the periodic table react together to form an ionic/electrovalent compound as illustrated in the question (shown below).
Sr + Cl₂ ⇒ SrCl₂
Because, members of group 2 react well with halogens to form an ionic/electrovalent compound, Sr can also react with iodine (I₂) or bromine (Br₂), any of which can be our X₂ (because the reactions are similar to that of how Cl₂ react), as shown below
Sr + I₂ ⇒ SrI₂
Sr + Br₂ ⇒ SrBr₂
A molecule, X₂, that is likely to react with Sr in a way similar to how Cl₂ reacts with Sr is F₂
Scrontium (Sr) is an Alkaline earth (i.e group 2) metal. It has 2 valence electrons and form bond by losing the two valence electrons.
Sr —> Sr²⁺ + 2e¯...... (1)
Chlorine (Cl) is a group 17 element (i.e Halogen). It has 7 valence electrons and form bond by accepting electron 1 to completely its octet configuration.
Cl + e¯ —> Cl¯.... (2)
Combining equation 1 and 2, we have
Sr + 2Cl + 2e¯ —> Sr²⁺ + 2Cl¯ + 2e¯
Cancel out 2e¯
Sr + 2Cl —> Sr²⁺2Cl¯
Sr + Cl₂ —> SrCl₂
NOTE: Group members has similar chemical properties. Therefore, other members of group 17 (i.e fluorine, bromine, iodine) can under go similar reaction with Scrontium (Sr).
For example Fluorine:Sr —> Sr²⁺ + 2e¯...... (1)
F + e¯ —> F¯.... (2)
Combining equation 1 and 2, we have
Sr + 2F + 2e¯ —> Sr²⁺ + 2F¯ + 2e¯
Cancel out 2e¯
Sr + 2F —> Sr²⁺2F¯
Sr + F₂ —> SrF₂
Thus, fluorine molecule, F₂, will react with Sr in a way similar to how Cl₂ react.
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describes changes
in energy during a chemical reaction?
Answer:
Yes
Explanation:
Chemical reactions often involve changes in energy due to the breaking and formation of bonds. Reactions in which energy is released are exothermic reactions, while those that take in heat energy are endothermic.
Exothermic reaction - A chemical reaction in which heat energy is given out .
Buring of natural gas , respiration, formation of compost from vegetables matter also exothermic processes.
Examples
C(s)+O2(g)⸻➤CO2(g)+94.00kcal
2H2(g) +O2(g)⸻➤2H2O(l) +136.0kcal
Endothermic reaction - A chemical reaction in which heat energy is absorbed is called endothermic reaction.
Example
C(s)+2S⸻➤CS(l)-22kcal
C(s)+H2O⸻➤CO(s) +H2(s)-31.4 kcal
{ ⸻➤at 1100°C }
Determine which physical conditions are necessary to support nuclear fusion and formation of stars.
lower temperature
higher temperature
increased gravitational attraction
decreased gravitational attraction
Promotes Stellar Formation
Does Not Promote Stellar Formation
Answer:
Promotes Stellar Formation:
-Increased Gravitational Attraction
-Higher Temperature
Does Not Promote Stellar Formation:
-Decreased Gravitational Attraction
-Lower Temperature
Explanation:
Stars need at least three million kelvins to form, and the gravitational attraction helps form the star in the first place.
The physical conditions that are necessary to support nuclear fusion and formation of stars are divided into two headings. They are:
Promotes Stellar Formation:
Increased Gravitational AttractionHigher TemperatureDoes Not Promote Stellar Formation:
Decreased Gravitational AttractionLower TemperatureThere are some conditions that needs to be put in place before Nuclear Fusion can occur. It often needs temperatures of about 100 million Kelvin.
The ions have to be placed together in close proximity to allow fusion to take place between them.
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C9H8O4 Aroms in formula
Answer:
hope this helps!!
MOLES OF ELEMENTS IN A FORMULA
type of element. For example, in a molecule of aspirin, C9H8O4, there are 9 carbon atoms, 8 hydrogen atoms and 4 oxygen atoms. compound. For example, one mole of aspirin contains 9 moles of carbon atoms, 8 moles of hydrogen atoms and 4 moles of oxygen atoms.
Explanation:
Use the drop-down menus to complete the statements.
Each organism in a population produces more offspring than can survive. This is called
.
In order for natural selection to occur, populations must have
.
When the environment changes, nature selects favorable
. Over time, these
in a population.
Answer:
(1) 3
(2) 2
(3) 1
(4) 2
Explanation:
Use the drop-down menus to complete the statements.
Each organism in a population produces more offspring than can survive. This is called
✔ overproduction
.
In order for natural selection to occur, populations must have
✔ variation
.
When the environment changes, nature selects favorable
✔ adaptations
. Over time, these
✔ build up
in a population.
1. The reproduction of more offspring than can survive by each organism in a population is called overproduction.
2. The various populations in an ecosystem must have variation, in order for natural selection to occur.
3. When the physical environment in an ecosystem changes, nature selects favorable adaptations.
4. Over time, these favorable adaptations build up in the population of living organism.
Natural selection can be defined as a biological process in which the species of living organisms possess certain traits, characteristics, and qualities that enables them to successfully adapt to various environmental factors, survive and reproduce, as well as passing on genes to subsequent generation. Some of the environmental factors that affects natural selection include the following;
Competition for foodClimate changePredatorsSex matesBased on evolution, living organisms that are best suited for the new environment would survive and reproduce when there is a change in the physical environment.
Consequently, nature selects favorable adaptations and they are passed on to the next generation (offspring). Over time, these favorable adaptations build up in the population of living organism, and then the population would evolve.
In conclusion, natural selection entails the survival of the fittest organism within an ecosystem.
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The sun emits electromagnetic waves at many frequencies, but mostly in the infrared, visible, and ultraviolet
spectrums. What kind of energy is this?
nuclear
radiant
thermal
chemical
HELP
Answer:
B: Radiant
Explanation:
E2021...I got you guys
Answer:
radiant
Explanation:
distinguish among a mixture, a solution, and a compound.
Consider a situation in which the enzyme is operating at optimum temperature and pH, and has been saturated with substrate. What is your best option for increasing the rate of the reaction?HintsIncrease the pH.Increase the temperature.Increase the enzyme concentration.Increase the substrate concentration.
Answer:Increase the enzyme concentration
Explanation:
If the enzyme is saturated, it simply means that all the enzyme molecules present has been bound to substrates.
Of course, there will still be more substrates left in the system since the enzyme is saturated. The reaction rate can now be increased by increasing the enzyme concentration so that more enzyme molecules can be bound to substrates.
Why would hand sanitizers not be as effective as detergents to clean your
clothes in a washing machine?
Hand sanitizers are not effective to be used for cleaning clothes are they can lead to spots.
Hand sanitizers for hygiene:Hand sanitizers can cause smirch-like flaws on clothing. Some contain alcohol, a known stain remover. When the sanitizer comes into contact with clothing, it can dispose of the assortment from the surface. The engravings are known as blurring spots.
Thus, for washing clothes detergents are used due to their properties.
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Please help me! I will give a 7 point Brainliest and 13 points!
What is the molarity of a solution prepared from 19.4 g NaCl in 300.0 mL of solution?
Answer:
1.11 M NaCl
Explanation:
Quizlet???
[20 points] What kind of bond is pictured in the diagram to the left? Describe the movement of the valence electrons in the bond above? (Hint: Sharing or giving up?)
Answer: The kind of bond is a covalent bond.
Explanation: The two atoms on top are separated or not together while the other is. the two atoms on top are negative while only one molecule on the bottom is negative. And, the top pair is atoms and the bottom pair is molecule
Sodium and chloride ions readily combine because they have opposite charges.
O True
O False
HURRY!!!
Answer:
its true i just looked on quizlet
Explanation:
8. Your pigs are going through ten 50.0 lb bags of feed per week. How many kilograms of feed are the pigs
eating per day?
HELP ME PLEASE
Answer:
8. 3.24 kg
9. 6.31 litres/minute.
10a. 15.3 m³
10b. $ 612.
Explanation:
8. Determination of the kilogram of feed eaten by the pig per day.
From the question given,
The pig consumed = 50 lb bags
Duration = 1 week
Consumption per day =..?
Next, we shall convert 50 lb to kg. This can be obtained as follow:
1 lb = 0.454 Kg
Therefore,
50 lb = 50 lb × 0.454 Kg/ 1 lb
50 lb = 22.7 kg
Next, 1 week us equivalent to 7 days.
Thus, the pigs consumed 22.7 kg of feed in 7 days. Therefore, the pigs will consume X kg of feed in 1 day i.e
X kg of feed = 22.7/7
X kg of feed = 3.24 kg
Therefore, the pigs will consume 3.24 kg of feed per day.
9. Determination of the rate in litres/minute.
Rate = 100 gallon/hour
Rate (litres/minute) =?
We'll begin by converting 100 gallon/hour to litre/hour. This can be obtained as follow:
1 gallon/hour = 3.785 litres/hour
Therefore
100 gallon/hour = 100 × 3.785
100 gallon/hour = 378.5 litres/hour
Finally, we shall convert 378.5 litres/hour to litres/minute. This can be obtained as follow:
1 litre/hour = 1/60 litre/minute
Therefore
378.5 litres/hour = 378.5 × 1/60
378.5 litres/hour = 6.31 litres/minute.
Therefore, 100 gallon/hour is equivalent to 6.31 litres/minute.
10a. Determination of the concrete in m³.
Concrete needed = 20 yd³
Concrete needed (in m³) =...?
1 yd³ = 0.765 m³
Therefore,
20 yd³ = 20 yd³ × 0.765 m³/ 1 yd³
20 yd³ = 15.3 m³
Therefore, 20 yd³ is equivalent to 15.3 m³
10b. Determination of the cost spent on the wall. This can be obtained as follow:
1 m³ = $ 40
Therefore,
15.3 m³ = 15.3 m³ × $ 40 / 1 m³
15.3 m³ = $ 612
Therefore, $ 612 will be spent on the wall.
17.0cm
23.0cm
4.00cm
A 38.6 kg marble slab is shown above. What is its density?
g/cm3
Answer:
24.68 g/cm³
Explanation:
We'll begin by calculating the volume of the marble. This can be obtained as follow:
Volume = 17 × 23 × 4
Volume = 1564 cm³
Next, we shall convert the mass of the marble (i.e 38.6 kg) to grams (g). This can be obtained as follow:
1 kg = 1000 g
Therefore,
38.6 kg = 38.6 kg × 1000 g / 1 kg
38.6 kg = 38600 g
Therefore, 38.6 kg mass of the marble slab is equivalent to 38600 g.
Finally, we shall determine the density of the marble slab as follow:
Volume = 1564 cm³
Mass = 38600 g.
Density =..?
Density = mass /volume
Density = 38600 g / 1564 cm³
Density = 24.68 g/cm³
Therefore, the density of the marble slab is 24.68 g/cm³
What color is a mirror?
Answer:
mirrors do not have a color, many people believe they are green because they reflect the most green light back into our eyes.
again with the chemistry questions all help is appreciated :’)
Answer:
The answer is Rubidium
Explanation:
The number of protons is unique for each element. It is also identified as an element’s atomic number. Look for an element with the number of protons as the atomic number to find the unidentified element.
Answer:
Hello again, I think the option will be the third one Rubidium im highly sure because the periodic table goes by the number of protons which in your question is 37. So yeah it will be rubidium.
Explanation:
Look for 37 protons in the periodic table.
According to the law of conservation of matter, what cannot change during a chemical reaction?.
OA. the number of atoms
ОВ.
the color of substances
OC.
the state of matter
OD. the temperature
What cannot we change during a chemical reaction
Answer:
the number of atoms
Explanation:
atoms are never created not destroyed
Describe the relationship between atoms and molecules
Answer:
Atoms are the smallest particle that an element can be divided in to. When atoms come together, they form molecules and molecules start to create everything around you.
Atoms are the smallest particles of matter which on combining with atoms of the same type give rise to molecules.
What is matter?
Matter is a substance which is made up of various types of particles which occupy space and have inertia . All living things and objects are made up of various types of particles that occupy space and have inertia .
Depending on temperature and other factors matter is able to exist in different phases. Most common of which are solid, liquid and gas. Matter can exist in more than one state depending on the temperature and pressure .
State of matter can be changed by heating or cooling and even by changing the applied pressure.When a state changes matter does not break rather its state changes though its chemical composition remains same.
Physical characteristics of matter are shape, color, size and temperature. Every matter is made up of elements which cannot be broken down further by ordinary chemical reactions.
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A student has an unknown sample. How can spectroscopy be used to identify the sample?
It can identify the elements in the sample.
It can determine the number of electrons in the sample.
It can determine the ratio of the elements in the sample.
It can determine the molecular structure of atoms in the sample.
Answer: A. It can identify the elements in the sample.
Explanation: on edge
Spectroscopy is the technique used in analytical chemistry. An unknown sample can be identified by spectroscopy as it can determine the elements. Thus, option A is correct.
What is spectroscopy?Spectroscopy is an analytical technique that can determine the atomic and molecular structure of the sample by the method of absorption and emission of the energy by the particles of the matter.
The particles or the atomic elements absorb the electromagnetic radiation from the source and emit a specific spectrum or wavelength that is a characteristic of an element.
This spectrum allows the deduction of the structural details and the electronic configuration that is used to know the element or the atom present in an unknown sample.
Therefore, option A. spectroscopy can identify the elements in the unknown sample.
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Which properties change the composition of a substance?
A. chemical properties
B. chemical and physical properties
C. physical properties
D. neither chemical nor physical properties
Answer:
ok
Explanation:
Which properties change the composition of a substance?
A. chemical properties
B. chemical and physical properties
C. physical properties
D. neither chemical nor physical properties
Answer:
chemical properties
Explanation:
chemical properties did change the composition of substance, so it cannot go back to original anymore, such as burning, rusting, etc.
I took the test before. I got all the answer correct and got 100% score.
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Learning Properties of Matter Quiz Unit 2 Lesson 11 Grade 8
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After throwing the ball in the pool for my dog the ball sprung a leak and begin to fill with water. How many mL of water can the ball absorb before the ball sinks
Answer: i think 250ML
Explanation:
in periodic table, valance electrons are indicated by
Hi! i’m not sure which one this is, please help. (:
Answer:
Explanation:
-"If he wanted to keep 'em after he was dead, a wicked old screw," pursued the woman, "why wasn’t he natural in his lifetime? If he had been, he'd have had somebody to look after him when he was struck with Death, instead of lying gasping out his last there, alone by himself."
This is showing that if he hadn't be so selfish and righteous, then he would not have been alone to die without anyone there to help or comfort him. In the line, "why wasn't he natural in his life?", is asking why he wasn't a nice person. Why didn't he help others. If he had helped others, he would not have been so alone.A story set during a major battle, as both have a sudden rush of events.
Which scientist developed the 1st model of the atom that showed the structure of the inside of an atom?
A. Dalton
B. Borh
C. Rutherford
D. Thomson
what is density?????? any help anyone
Answer:
Density, mass of a unit volume of a material substance
Explanation:
Answer:
Hello!
Explanation:
Density: The degree of compactness of a substance.
happy to help!
An area of the atom that holds negative particles
Atoms consist of three basic particles: protons, electrons, and neutrons. The nucleus (center) of the atom contains the protons (positively charged) and the neutrons (no charge). The outermost regions of the atom are called electron shells and contain the electrons (negatively charged).
PLEASE HELP ME AGAIN!!!!! Explain the observed pattern of how the sizes and charges of atoms change with the addition and subtraction of electrons.
Answer: Positive ions that have lost an electron are smaller than their neutral atoms. Negative ions that have gained an electron are larger than their neutral atoms.
Explanation: I found this in my chemistry textbook.
Neutral atoms increase in size down a group and decrease across a period.
If neutral atom gains or loses an electron, forming anion or cation, increase or decrease in radius occurs and this trend differs from that of atomic radii.
What is atomic radii ?Atomic radius or Radii is defined as the total distance from the nucleus of the atom to the outermost orbital of its electron, similar to radius of a circle.
The determination of the atomic radii is difficult due to the uncertainty in the position of the outermost electron, so Heisenberg’s Uncertainty Principle is applied to obtain a precise measurement of the radius.
An atom also show different radii depending on the type of bond, hence there is no fixed radius of an atom.
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Andy is waiting at the signal. As soon as the light turns green, he accelerates his car at a uniform rate of 8.00 meters/second2. What is the displacement of Andy’s car after 30.0 seconds?
A.
1200 meters
B.
2400 meters
C.
3600 meters
D.
4800 meters
E.
7200 meters