Pls assist if you can.
Reasons why hydrogen was chosen as a standard reference to other elements

NaCl(s)=NaCl(aq) is a physical change as it represents a state change from solid to aqueous but retains the same chemical nature, Sodium Chloride (NaCl). The other choices show chemical changes.

The correct option is c.

The question is asking which of the choices represents a physical change. A physical change involves changes in the state of a substance but not its chemical nature. The best answer here is option C: NaCl(s)=NaCl(aq). In this reaction, solid sodium chloride (NaCl) is dissolving in water to form an aqueous solution, which is just a change in the state from solid to aqueous but the chemical nature (NaCl) remains the same. This is a clear demonstration of a physical change whereas options A, B, and D show chemical changes where new substances are formed.

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C. [tex]NaCl(s) \rightarrow NaCl(aq)[/tex]  shows a physical change.

A physical change is a type of change in which the form of matter is altered, but one substance is not transformed into another. Examples of physical changes include changes in state such as melting, freezing, and dissolving.

A. [tex]H_2(g) + O_2(g) \rightarrow H_2O(l)[/tex]
This is a chemical change because new substances with different chemical properties are formed: hydrogen and oxygen combine to form water.

B. [tex]2CH_3OH(l) + 3O_2(g) \rightarrow 2CO_2(g) + 4H_2O(l)[/tex]
This is another chemical change, involving the combustion of methanol to form carbon dioxide and water.

C. [tex]NaCl(s) \rightarrow NaCl(aq)[/tex]
This is a physical change. When sodium chloride (table salt) dissolves in water, it dissociates into ions but does not undergo any chemical change.

D. [tex]2AgNO_3(aq) + CaBr_2(aq) \rightarrow 2AgBr(s) + Ca(NO_3)_2(aq)[/tex]
This is a chemical change, where silver nitrate and calcium bromide react to form silver bromide and calcium nitrate, both of which are new substances.

Answer: (2) Black bears have 74 chromosomes and 37 haploid chromosomes. (3) The bears become s3xually mature anywhere from 3-7 years. (4) There are two types of reproductive barriers: Prezygotic and Postzygotic.

Explanation:

37 chromosomes are in the black bears sex cells bears,Sex cells only contain half the number of chromosomes found in the body cells.

The body cell of an American black bear contains 74 chromosomes, then each sex cell contains 37 chromosomes.

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The correct answer is option D, that is, increased coastal flooding.  

The change in climate is enhancing the frequency of coastal flooding, comprising floods just from tides. The combination of melting of ice into the oceans and expansion of water as the ocean has warmed has increased the level of the sea up to about seven inches since 1900, and the elevation is on the rise.  

From 2005 to 2015, the average number of floods has doubled along the stretch of coast from Florida to North Carolina. The flooding will become even more usual in the coming time as the concentration of greenhouse gases discharged into the atmosphere will increase the levels of the sea in years to come.  

Hey there!

"Which process responsible for the growth a repair of human tissue?"

Well, it heals itself which is called the mitosis but none of those are your answer choices .. the one that seems to be closer to those two results would be: Option 3. [tex]\boxed{cell-division}[/tex]

Therefore, your answer would most likely be: [tex]\boxed{cell-division}[/tex]

Good luck on your assignment and enjoy your day!

~[tex]LoveYourselfFirst:)[/tex]

A rock's exposure to the weathering elements and its surface area can affect its rate of weathering. Rocks that are constantly bombarded by running water, wind, and other erosion agents, will weather more quickly. Rocks that have a large surface area exposed to these agents will also weather more quickly.

Answer:

The surface area of a rock and the rate of weathering is directly related to one another. When a rock of large surface area is exposed to the atmosphere, then the factors such as rainfall, temperature, wind will affect the rock by weathering and erosion, depending upon the latitude of the area.

In the high latitudinal areas, these fractures in the rocks can trap the water during rainfall, and this water at night freezes as a result of which the volume of water increases by about 9%. Due to this the volume expands and exerts a force that ultimately leads to the weathering of rocks. The surface area when exposed more including these fractures

Due to the frequent changing of the temperature in some regions, the rocks undergo the expansion and contraction process. As a result of which the rock fractures and weathers.

In the tropical region, because of the maximum amount of sunlight and rainfall, the rocks are more prone to weathering. The agents namely wind, water will directly flow over the surface of the rock, thereby breaking down the rock particles. So the rate of weathering (both physical and chemical) is higher when the rock surfaces are highly exposed.

Using the periodic table, the element Rb, Rubidium is a member of the Alkali metal (Group IA) of the periodic table.

The periodic table is a systematic arrangement of elements in order of their atomic number into a set of 8 primary Columns each of which is called a Group and a set of 7 rows each of which is called a Period.

Ultimately, Rb, Rubidium is a member of the Alkali metal (Group IA) of the periodic table.

Other notable group include:

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Answer: Chemical Reactions, Acids, and Bases Unit Test

1. 24 mL of Mg burn in 32mL O2 to produce 56 mL of MgO

2. 92.4

3. Bonds of the reactants are broken, and bonds of the products are formed

4. The reaction rate decreases

5. in chemical equilibrium

6. The equilibrium shifts to the right and more products are formed

7. the I ion and the positive end of a water molecule

8. Less than 0 degree Celsius

9. Greater than

10. Solubility

11. feels slippery

12. MgCl2 and H2O

13. accept a proton and become NH4+

14. stay about the same

15. electrolyte

These are the answers I put for the short answers:

16. The double-replacement is KBr+. The resulting compound is AgNO3+AgBr

17. The ion that is formed is Br. The bromine gets reduced

18. Buffer solution is a solution that is resistant to large changes in pH

19. The peaks are called the activation energy. It is energy used to get the reaction going.

20. It is supersaturated

21. According to the figure above detergent is a base

Part 2: These are the answers that I put as well

1. 4Fe+3O2=2Fe2O3  3:2

2. 1.31M

3. 300mg of water

4. 60.46 kJ would be absorbed during the reaction

Answer: by lowering the activation energy.

Explanation:

Activation energy is the extra energy that must be supplied to reactants in order to cross the energy barrier and thus convert to products.

A catalyst is a substance which increases the rate of a reaction by taking the reaction through a different path which involves lower activation energy and thus more molecules can cross the energy barrier and convert to products.

The catalyst itself does not take part in the chemical reaction and is regenerated as such at the end.

Answer:

C. The same amount of work is done on each box.  

Step-by-step explanation:

The formula for work (w) done is

w = f×d

Box A:

w = 3 × 2

w = 6 J

=====

Box B:

w = 2 × 3

w = 6 J

The same amount of work is done on each box

The reaction between NaC₂H₃O₂(aq) and Pb(NO₃)₂(aq) does occur, but the products formed are soluble and therefore do not precipitate out. The equation for this reaction is:.

[tex]NaC2H3O2(aq) + Pb(NO3)2(aq) → Pb(C2H3O2)2(aq) + 2NaNO3(aq)[/tex]

The reaction is a double displacement reaction, where the two reactants exchange ions to form new products. In this case, the lead ion (Pb²+) from Pb(NO₃)₂(aq) replaces the sodium ion (Na+) in NaC₂H₃O₂(aq) to form

[tex]Pb(C2H3O2)2(aq) and NaNO3(aq).Pb(NO3)2(aq) + 2NaC2H3O2(aq) → Pb(C2H3O2)2(aq) + 2NaNO3(aq)[/tex]

Since both products, Pb(C₂H₃O₂)₂(aq) and NaNO₃(aq), are soluble in water, they remain in solution and do not form a solid precipitate. Therefore, it may appear that no reaction has occurred.

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Answer: [tex]5.2\times 10^{22} atoms[/tex] of iodine are present in 12.75 grams of [tex]CaI_2[/tex].

Explanation:

[tex]moles=\frac{\text{given mass of the compound}}{\text{molar mass of the compound}}[/tex]

Moles of Calcium iodide :

Moles of [tex]CaI_2=\frac{12.75 g}{293.8 g/mol}=0.0433 moles[/tex]

number of molecules of [tex]CaI_2[/tex] in 0.0433 moles = [tex]N_A\times \text{number of moles}=6.022\times 10^{23}\times 0.0433=2.60\times 10^{22} molecules [/tex]

In one molecule of calcium iodide there are two iodine atoms, then number of iodine atoms in [tex]2.60\times 10^{22} molecules [/tex] of [tex]CaI_2[/tex]

[tex]2\times 2.60\times 10^{22} atoms=5.2\times 10^{22} atoms[/tex]

Hence, there are [tex]5.2\times 10^{22} atoms[/tex] of iodine are present in 12.75 grams of [tex]CaI_2[/tex].

Answer: The correct answer is Option A.

Explanation:

From the given options:

A. Ionic bonds: These bonds are formed when there is complete transfer of electrons from one atom to another atom. An atom which looses electrons is known as electropositive atom and the atoms which gains electrons is known as electronegative atom.

B. Covalent Bonds: These bonds are formed when there is sharing of electrons between the two atoms.

C. Metallic bonds: These bonds are formed from the attraction between the free electrons and fixed positively charged of two metallic atoms.

D. Polyatomic Bonds: These bonds are formed between the species forming a polyatomic ion.

From the given information, the correct answer to this question is Option A.

Answer:

The correct answer here is ionic bond

Explanation:

This problem can be solved by Dalton's law of  partial pressures which states that  in a mixture of non-reacting gases, the total pressure exerted is equal to the sum of the partial pressures of the individual gases.

Ptotal = P₁ + P₂ + P₃ + ..... + Pn

Herein, Ptotal = P(Ne) + P(Ar) + P(He)

Ptotal = 1.25 atm, P(Ne) = 0.68 atm and P(Ar) = 0.35

So, P(He) = Ptotal - P(Ne) - P(Ar) = 1.25 - 0.68 - 0.35 = 0.22 atm

Answer:

0.22 atm

Explanation:

took test

Answer: 120

Explanation:

Volume of the gas is defined as the space occupied by a substance. It is expressed in units like [tex]cm^3[/tex], [tex]m^3[/tex] , L and ml.

All these units of volume are inter convertible.

We are given:

Volume of the gas = [tex]120ml[/tex]

Converting this unit of volume into [tex]cm^3[/tex] by using conversion factor:

[tex]1cm^3=1ml[/tex]

[tex]120ml=\frac{1}{1}\times 120=120cm^3[/tex]

Thus the volume in [tex]cm^3[/tex] would be 120.

The very last option is the correct answer.

Answer: Option (4)

Explanation: For the formation of a tornado, warm air must meet the cold air.

Initially, the warm air present in the lower atmosphere, gets heated up, being less dense, rises up and mixes up with the cold and denser air mass present in the upper atmosphere. Due to this collision of both the air masses, and the presence of water vapor, it gets converted into water droplets and formation of clouds. With time a more intense funnel forms due to the wind from all direction and forms a tornado.

Thus, the correct answer is option (4).

Empirical Formula = C20 H60 HG1 S1 O4 (numbers should be in subscript)

Percent Composition =

MG = 43%

S = 56.8%

The electrostatic attraction between positively charged nuclei and negatively charged electrons permits two atoms to be held through either a covalent bond, where the electrons are shared between atoms, or an ionic bond, where one atom donates or accepts an electron from the other, creating ions which are attracted to each other.

The electrostatic attraction between positively charged nuclei and negatively charged electrons allows two atoms to be held together through what is known as a covalent bond or an ionic bond. In a covalent bond, these forces of attraction are between the nuclei of a molecule's atoms and pairs of electrons between these atoms. For instance, in an oxygen molecule O₂, the electrons are equally shared between the atoms, establishing a covalent bond.

On the other hand, in an ionic bond, a atom donates or accepts an electron resulting in a positively or negatively charged atom, termed as an ion. For example, a sodium (Na) atom can donate its 2s electron to a chlorine (Cl) atom. This results in a positively charged Na+ ion and a negatively charged Cl- ion. The electrostatic attraction between these charged ions creates an ionic bond and forms a salt molecule (NaCl).

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Final answer:

The triple point on a phase diagram represents the only combination of temperature and pressure at which all three phases can exist simultaneously and are in equilibrium.

Explanation:

The triple point on a phase diagram refers to the point where the solid/liquid, liquid/gas, and solid/gas lines intersect. It represents the only combination of temperature and pressure at which all three phases can exist simultaneously and are in equilibrium. An example is the triple point of water, which occurs at 273.16 K (0.01°C). At this point, water can exist simultaneously as solid ice, liquid water, and water vapor.

Ice caps would float therefore providing insulation for aquatic life and ensuring they do not freeze due to the cool temperature.

Answer is: step 3 would be placed C.

This is example of chemical change (chemical reaction), because new substances are formed (gas is emitted), the atoms are rearranged.

Physical property can be observed and measured without any changes in molecular composition. The same substance is present before and after the psysical change, just with different form or state of matter.

Chemical reaction: powder + water → new substance + gas.

Answer:

The correct answer is C

Explanation:

A) The chemical equilibrium will shift to the right, favoring the forward reaction.

The forward reaction absorbs heat. It is endothermic. Going in that direction will remove heat from the system. The temperature of the system will drop.

The reverse reaction produces heat. It is exothermic. Converting products back to reactants will adds to the heat of the system. The temperature of the system will increase.

By the Le Chatelier's Principle, a system in equilibrium will respond to changes in a way that minimizes their effect.

In this question, the change is an increase in temperature. The system will seek to reduce its temperature. It will favor the forward reaction, which is endothermic and removes heat from the system.

Temperature of the system will decrease. There will be more products and less reactants. The equilibrium will shifts to the left.

The chemical equilibrium will shift to the right, favouring the forward reaction. Hence, option A is correct.

Chemical equilibrium is the condition in the course of a reversible chemical reaction in which no net change in the amounts of reactants and products occurs.

The forward reaction absorbs heat. It is endothermic. Going in that direction will remove heat from the system. The temperature of the system will drop.

The reverse reaction produces heat. It is exothermic. Converting products back to reactants will add to the heat of the system. The temperature of the system will increase.

By Principle, a system in equilibrium will respond to changes in a way that minimizes their effect.

In this question, the change is an increase in temperature. The system will seek to reduce its temperature. It will favour the forward reaction, which is endothermic and removes heat from the system.

The temperature of the system will decrease. There will be more products and fewer reactants. The equilibrium will shift to the left.

Hence, option A is correct.

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Answer is: the nucleus of a helium atom.

Alpha particle is nucleus of a helium-4 atom, which is made of two protons and two neutrons.

For example, nuclear reaction:

²³⁴U → ²³⁰X + α (alpha particle).

Alpha decay is radioactive decay in which an atomic nucleus emits an alpha particle (helium nucleus) and transforms into an atom with an atomic number that is reduced by two and mass number that is reduced by four.

a helium nucleus emitted by some radioactive substances, originally regarded as a ray.

Final answer:

Plate tectonics and the uplift of mountains due to the movement of Earth's tectonic plates explain the presence of marine fossils found on mountains far from any ocean or sea.

Explanation:

Fossils of marine animals found on mountains far from any ocean or sea can be explained by the concept of plate tectonics. Plate tectonics is the theory that the Earth's outer shell is divided into several plates that move and interact with each other.

Over millions of years, the movement of these plates can cause mountains to form and previously submerged areas to be uplifted. Fossils of marine animals found on mountains suggest that these areas were once underwater and have since been uplifted due to plate tectonic forces.

For example, the presence of marine fossils on the Himalayan mountains is evidence that the Indian subcontinent was once located in the ocean and collided with the Eurasian plate, causing the formation of the Himalayan mountain range. The uplift of the mountains exposed the fossils that were once buried deep in the ocean floor.

In summary, the best explanation for marine fossils found on mountains far from any ocean or sea is plate tectonics and the movement of Earth's tectonic plates.

he can lift 440.925 pounds

Macho Mel can lift approximately 440.924 pounds, as 200 kilograms is equal to 440.924 pounds when using the conversion factor of 1 kilogram being approximately 2.20462 pounds.

To convert kilograms to pounds, one must use the conversion factor where 1 kilogram equals approximately 2.20462 pounds. So, by multiplying 200 kilograms by this conversion factor, we find that Macho Mel can lift:

200 kg x 2.20462 lbs/kg = 440.924 lbs

Therefore, Macho Mel can lift 440.924 pounds with ease.

Solid! The molecules in solid matter are arranged closely together and packed quite tightly to maintain a regular shape. Hope this helps!

Answer: Option (c) is the correct answer.

Explanation:

It is known that in a solid, molecules are held together by strong intermolecular forces of attraction. As a result, they are unable to move from their initial place but they can vibrate at their mean position.  

Hence, in solid substances the molecules have low kinetic energy.

On the other hand in liquids, the molecules are held by less strong intermolecular forces of attraction as compared to solids. Due to which they are able to slide past each other. Hence, they have medium kinetic energy.

Whereas in gases, the molecules are held by weak Vander waal forces. Hence, they have high kinetic energy due to which they move rapidly from one place to another leading to more number of collisions.

Hence, gases are able to expand more rapidly as compared to liquids.

Thus, we can conclude that out of the given options solid is a matter phase in which the molecules are arranged on a matrix and close together.

The answer is; A

During a hot day, the land heats up faster than the waters. The air on land becomes warm and less dense fast and begin to rise in the atmosphere. The air on the ocean with is still cooler and denser moves in to replace the rising on land air. This causes a sea breeze. The sea breeze carries with it, moisture. The hotter the day the higher the humidity. When the air goes inland, it causes precipitation when it rises,  cool, and condenses.

Answer:

I got it Right

Explanation:

In Study Island

Drinking one standard drink will increase your BAC by about 0.02 (remember this can depend on the factors mentioned above). As your BAC rises, so does your risk of being involved in a crash. This is why drivers with an open licence have to keep under a BAC of 0.05.

D - are more organized

Answer: Are less organized

Explanation:

The formation of a solid has to do with a very ordered arrangement of molecules in a regular repeating pattern. The arrangement of molecules must be neat enough to allow close packing of the ordered arrangement. Ionically bonded species have a neat arrangement of oppositely charged ion pairs. This accounts for their abundant existence in the solid state. There is less order in the packing of covalent molecules as they as mostly held by weak intermolecular forces. Hence they exist mostly as liquids and gases.