Categories
Assignment Help

A center lane with solid and broken yellow lines that is used by vehicles making left turns in both directions is called a:

[ad_1]

Left turn lane

Left turn lanes are used when vehicles are turning left. It is mandatory for a vehicle to come inside the lane completely and then wait for the traffic to clear before making the turn. The vehicle is not allowed to be half inside the lane and half outside, blocking the traffic and producing dangerous driving conditions.

[ad_2]

Categories
Assignment Help

E. solid copper sulfide and silver nitrate react to form copper (ii) nitrate and solid silver sulfide. write a balanced chemical equation that describes the reaction. identify the oxidation number of each element in the reaction. (you do not need to include the total contribution of charge.) is this reaction a redox reaction or a non-redox reaction? explain your answer.

[ad_1]

Answer:

The given reaction is not a redox reaction.

Explanation:

Redox reaction is defined as chemical reaction in oxidation and reduction reactions occurs simultaneously.

Oxidation reaction is defined as the reaction in which an atom looses its electrons. Here, oxidation state of the atom increases.

Reduction reaction is defined as the reaction in which an atom gains electrons. Here, oxidation state of the atom decreases.

Solid copper sulfide when immersed in silver nitrate solution it reacts to form silver sulfide precipitate and copper(II) nitrate solution.

CuS(s)+2AgNO_3(aq)rightarrow Cu(NO_3)_2(aq)+Ag_2S(s)

Oxidation states of elements on reactant side:

Oxidation state of copper  = +2

Oxidation state of sulfur = -2

Oxidation number of silver  +1

Oxidation number of nitrogen = +5

Oxidation number of oxygen = -2

Oxidation states of elements on product side:

Oxidation state of copper  = +2

Oxidation state of sulfur = -2

Oxidation number of silver  +1

Oxidation number of nitrogen = +5

Oxidation number of oxygen = -2

No change in oxidation states of elements is observed which means that the given reaction is not a redox reaction.

[ad_2]

Categories
Assignment Help

A cone is a solid made from a disc, any point on that disc, and all points between them. True or False

[ad_1]

Answer with Explanation:

Disc, is a three dimensional shape,made up of circles of different radii and is uncovered from top.Different from Bowl,which is quite deeper, do not extend far down from top.

So,to make a cone , you have to take three points on the surface of the disc such that it forms a triangular shape,and when you cut it,you will get a shape similar to cone.

So, it is a false statement, which asserts that, A cone is a solid made from a disc, any point on that disc, and all points between them.  

[ad_2]

Categories
Assignment Help

Select all that apply. Which of the following statements are true? A solid can diffuse into a liquid, but a solid cannot diffuse into another solid. A solid can diffuse into both a liquid and another solid. A liquid can diffuse into another liquid. A gas can diffuse into another gas.

[ad_1]

Select all that apply. Which of the following statements are true? A solid can diffuse into a liquid, but a solid cannot diffuse into another solid. A solid can diffuse into both a liquid and another solid. A liquid can diffuse into another liquid. A gas can diffuse into another gas.

[ad_2]

Categories
Assignment Help

WILL GIVE BRAINLIEST PLEASE HELP!! Describe the relationship of the Earth’s lithosphere to the asthenosphere. The asthenosphere is composed of rigid plates that “float” on top of the lithosphere. The lithosphere is composed of rigid plates that “float” on top of the asthenosphere. The lithosphere is a solid wall around the asthenosphere, and they move as one unit. The asthenosphere is found in the Earth’s core and is protected by the lithosphere.

[ad_1]

Answered by answersmine AT 22/10/2019 – 03:13 AM

Asthenosphere, zone of Earth’s mantle lying beneath the lithosphere and believed to be much hotter and more fluid than the lithosphere. The asthenosphere extends from about 100 km (60 miles) to about 700 km (450 miles) below Earth’s surface.The asthenosphere is almost solid, although some of its regions could be molten. Both the lithosphere and asthenosphere make up the mantle. The answer is B. Hope this helps 🙂

[ad_2]

Categories
Assignment Help

HELP PLEASE! 3 SCIENCE QUESTIONS! I'm stuck on my last 3. #1 Compare and contrast chemical change and physical change. #2 Compare and contrast a gas and a plasma. #3 What state of matter has the electrons separated from the nuclei of the atoms? Gas Solid Liquid Plasma

[ad_1]

HELP PLEASE! 3 SCIENCE QUESTIONS! I’m stuck on my last 3. #1 Compare and contrast chemical change and physical change. #2 Compare and contrast a gas and a plasma. #3 What state of matter has the electrons separated from the nuclei of the atoms? Gas Solid Liquid Plasma

[ad_2]

Categories
Assignment Help

In the story “To Build a Fire,” what information did the man ignore? Even though the creeks freeze solid, liquid water exists near springs. Always make camp and build a fire while there is still daylight. Always take along survival gear and wear protective clothing. No one must travel alone in the Klondike after fifty degrees below zero.

[ad_1]

Answered by answersmine AT 22/10/2019 – 03:28 AM

No one must travel alone in the Klondike after fifty degrees below zero. I would say this is the main lesson to learn about this Jack London story which shows that nature can be cruel and unforgiving and at 50 degrees below zero it is nothing to fool with. If there are two people, one can help the other and warn say of snow which may fall down and douse the fire and also both can have matches to start a fire and they can discuss the best course of action in any situation which presents itself such as trusting the ice not to break over a creek for example.

Post your answer

[ad_2]

Categories
Assignment Help

Which best explains the symbolism behind Melville’s comparison of Ahab to a solid bronze cast in Chapter 28 of Moby? Melville is symbolizing the impermanent nature of Ahab’s character. Melville is symbolizing the intellectual nature of Ahab’s character. Melville is symbolizing the inflexible nature of Ahab’s character. Melville is symbolizing the impolite nature of Ahab’s character.

[ad_1]

The correct answer is c. Melville is symbolizing the inflexible nature of Ahab’s character.


Explanation:

Moby was written by American writer Herman Melville. The main character in this novel is the captain Ahab. We can see that Ahab is very obsessive and determined to kill the whale that hurt him. This guy has an inflexible nature.

[ad_2]

Categories
Assignment Help

Which statement best describes the movement of atoms in solid

[ad_1]

The correct answer is The energy absorbed in the first move is greater than the energy released in the second move.

An electron will absorb energy of a certain frequency to move from a lower energy state to a higher energy state. The energy absorbed will depend on how far apart the energy levels are. The more far apart the energy levels are , the bigger the energy that will be absorbed to make the transition.

Electrons emit energy when they move from a higher energy level to a lower energy level. The energy released by the electron will depend on how far apart the energy levels are. The more far apart the energy levels are, the more bigger the energy that will be released during the transition.

When the electron moves from energy level 1 to energy level 4 it absorbs more energy than that which it releases when it falls from energy level 4 to energy level 2. This is because energy level 1 and energy level 4 are further apart than energy level 4 and energy level 2.

[ad_2]

Categories
Assignment Help

As a substance changes phase from a gas to liquid to solid: A- The spacing between molecules increases. B- It's density generally increases. C- The spacing between molecules is not affected. D- It undergoes chemical change.

[ad_1]

As a substance changes phase from a gas to liquid to solid: A- The spacing between molecules increases. B- It’s density generally increases. C- The spacing between molecules is not affected. D- It undergoes chemical change.

[ad_2]

Categories
Assignment Help

What is the effect of temperature on the solubility of a solid in a liquid

[ad_1]

What is the effect of temperature on the solubility of a solid in a liquid

[ad_2]

Categories
Assignment Help

Natural Forces Affecting the Driver In one or more complete sentences, explain how natural laws apply to the following scenarios: How does inertia affect a person who is not wearing a seatbelt during a collision? How does kinetic energy affect the stopping distance of a vehicle traveling at 30 mph compared to the same vehicle traveling at 60 mph? How does kinetic energy affect the stopping distance of a small vehicle compared to a large vehicle? Keeping in mind the kinetic energy of a moving vehicle, how can a driver best prepare to enter sharp curves in the roadway? Using information about natural laws, explain why some car crashes produce minor injuries and others produce catastrophic injuries. Signs, Signals, and Pavement Markings Imagine you are taking a road trip! Select a destination and navigate the trip. Answer the following questions in one or more complete sentences: Where will you go on your trip? You approach a railroad crossing with a cross buck sign that has no lights or gates. What should you do? You arrive at an intersection with traffic lights that are not working because of a power outage. What do you do? There is a flashing yellow light at the intersection you are approaching. What does the flashing yellow light indicate, and what should you do to safely navigate this intersection? On the road you are traveling, the pavement markings change from broken white lines to solid white lines between the lanes of traffic. What does the line change mean? After an hour on the expressway, your passengers need to use the restroom and they want to get some food. As you approach the next exit, what color sign will you look for, and what type of information would you expect to see on that sign? When you take the exit ramp off the expressway and merge onto the next road, you see yellow lines dividing the roadway. What do the yellow lines tell you about the traffic flow?

[ad_1]

Natural Forces Affecting the Driver:

1. While the car stops, the person continues moving the way that the car were moving and then hits the obstacle in the car or the person can be thrown out of the vehicle. If the person wears belt, he will stop moving with the vehicle and won’t hit the obstacle.

2. We count approximate kinetic energy using the formula K = v^2. So the vehicle which is moving at 30 mph will have four times less kinetic energy than vehicle which is moving at 60 mph. If they have the same road conditions, the breaking distance will be four times as great for the car moving twice as fast.

3. Kinetic energy depends on object’s mass and velocity and it has direct relationship with the stopping distance. The lesser mass of the vehicle = the lesser kinetic energy and lesser stopping distance. => If both vehicles have the same velocity, then small vehicle has lesser kinetic energy than large vehicle.

4. We know that kinetic energy has this relationship with velocity K = v^2. So the best way to prepare to enter sharp curves in the roadway is to lower the speed. The most appropriate speed is 20-30 mph, but it depends on road conditions and car’s breaks condition.

5. Car crashes can happen with everyone so the best way is to be prepared. First the driver should wear a seatbelt while he’s driving. He should check his tires and breaks condition regularly. And also it’s important to slow down the vehicle while entering sharp curves. Without following these rules, the driver can get catastrophic injuries in a car crash.

Signs, Signals, and Pavement Markings: 

1. It doesn’t matter where you go. All you need is to learn highway code. It’s very different to know the meanings of every road sign. Also, it’s necessary to check your car’s conditions and you should take some spare parts for your car in case of accidents. So wherever you go, it’s important to be prepared.

2. You should stop before crossing and take few minutes to make sure there is no train approaching. If there is no train approaching, you can pass a railroad crossing. If you see approaching train, you should wait until it will pass a railroad crossing.

3. You should stop before the lights and wait to check the traffic movement and signs. Make sure that everything is safe and pass the intersection. Don’t move fast to avoid accidents.

4. Flashing yellow light means that it’s not necessary to stop but you should to pay attention on the traffic movement. So it would be better to yield before the lights and make sure if it’s safe to move. After that you can cross the intersection.

5. The line change means that the lane changes and you can’t cross solid lines. Pay more attention on road marking because it shows how you should behave on the road or highway.

6. As you approach the next exit and  your passengers need to use the restroom and get some food, you should look for green signs which indicate food and rest stops. You should to slow down if you don’t want to skip the sign.

7. When you take the exit ramp off the expressway and merge onto the next road, you see yellow lines dividing the roadway which indicates that there is oncoming traffic and this is a two-way highway. 

[ad_2]

Categories
Assignment Help

25. From left to right across a period in the periodic table, elements become less ___________ and more ______________ in their properties. 26. Francium has 36 isotopes, but only francium-223 occurs in nature. Francium-223 spontaneously emits particles and energy, so francium-223 is a(an) _____________ of francium. 27. At sea level, water ______________ at 100°C. 28. Cooking requires continuous addition of energy to the chemical reactions that are taking place. The chemical reactions involved in cooking can be described as __________________. 29. The ________________ theory of matter states that all particles of matter are in constant motion. 30. In Rutherford’s experiments, some of the _______________ aimed at gold atoms bounced back, suggesting that a solid mass was at the center of the atom. 31. You are given the melting points of three unknown substances and are asked to predict which one is an ionic compound. You would select the compound with the ________________ melting point. 32. A flight simulator that helps astronauts prepare for a shuttle launch is an example of a(an) __________________. 33. In the symbol ■([email protected]) He, the superscript 4 is the _________________ for helium, and the subscript 2 is the ___________________ for helium.

[ad_1]

25) Answer is: less metallic and more nonmetallic.

Electronegativity increases from left to right across a period, atoms have tendency to attract electrons.

Electronegativity (χ) is a property that describes the tendency of an atom to attract a shared pair of electrons.

26) Answer is: radioisotope.

Radioisotope has an unstable atomic nucleus and emit energy and particles when it changes to a more stable form.

Francium (Fr) is element with atomic number 87 (87 protons and 87 electrons).

27) Answer is: boils.

Boiling is the temperature at which the vapour pressure of the liquid is equal to the pressure exerted on the liquid by the surrounding atmosphere.

The Celsius scale was based on 0°C for the freezing point of water and 100°C for the boiling point of water at 1 atm pressure.

28) Answer is: endothermic.

There are two types of reaction:  

1) endothermic reaction (chemical reaction that absorbs more energy than it releases, ΔH>0).

2) exothermic reaction (chemical reaction that releases more energy than it absorbs).  

For example, the breakdown of ozone is an endothermic process. Ozone has lower energy than molecular oxygen (O₂) and oxygen atom, so ozone need energy to break bond between oxygen atoms.  

29) Answer is: kinetic.

The average kinetic energy of molecules depends on the temperature.  

As temperature increases, molecules gain more energy from surrounding and move faster.  

Kinetic energy (standard unit is the joule J) depends on speed of the molecule.  

Solid gains kinetic energy to become a liquid and then becomes a gas.

30) Answer is: alpha particles.

This was famous Rutherford’s Gold Foil Experiment: he bombarded thin foil of gold with positive alpha particles.

Rutherford observed the deflection of alpha particles on the photographic film.  

Alpha particles are helium atom particles, consist of two protons and two neutrons.  

According to Rutherford model of the atom: atoms have their charge concentrated in a very small nucleus.  

31) Answer is: highest.

For example, calcium oxide.

Calcium oxide (CaO) has ionic bonds between calcium cations (Ca²⁺) and oxygen anions (O²⁻).

Because it has strong ionic bonds, it has high melting point (around 2600°C).

Ionic bond is the electrostatic attraction between oppositely charged ions (cations and anions).

32) Answer is: a scientific model.

A scientific model is a representation of an idea, an object, a process or a system that is used to describe and explain phenomena that cannot be experienced directly.

33) Answer is: the superscript is mass number and the subscript is atomic number.

Atomic number(Z) is the number of protons, which is characteristic of a chemical element..

Mass number (A) is the total number of protons and neutrons in a nucleus.

[ad_2]

Categories
Assignment Help

At which point could the substance shown exist as a gas or a solid but not a liquid?

[ad_1]

Answer: The correct answer is all of these.

Explanation:

Organic compounds are defined as the chemical compounds where one or more carbon atoms are covalently bonded to other atoms of hydrogen, oxygen or nitrogen.

They occur naturally in nature and the main sources of these organic compounds are petroleum, coal and natural gases.

Petroleum are the naturally occurring substances which contain organic compounds in the form of gases, liquid or semi-solid. Thus, they are a major source of organic compound.

Coal is also a form of fossil fuel which are the major source of organic compound.

Natural gas contains hydrocarbons and also is the major source of organic compounds.

Thus, the correct answer is all of these.

[ad_2]

Categories
Assignment Help

Calculate the density of a rectangular solid, which has a mass of 25.71g. It is 2.30cm long, 4.01cm wide, and 1.82cm high

[ad_1]

This problem is to apply Roult’s Law.

Roult’s Law states that the vapor pressure, p, of a solution of a non-volatile solute is equal to the vapor pressure of the pure solvent, Po solv, times the mole fraction of the solvent, Xsolv

p = Xsolv * Po sol

X solv = number of moles of solvent / number of moles of solution

The solvent is water and the solute (not volatile) is glycerin.

Number of moles = mass in grams / molar mass

mass of water = 132 ml * 1 g/ml = 132 g

molar mass of water = 18 g/mol

=> number of moles of water = 132 g / 18 g/mol = 7.33333 mol

mass of glycerin = 27.2 g

molar mass of glycerin:, C3H8O3: 3 * 12 g/mol + 8 * 1 g/mol + 3*16 g/mol = 92 g/mol

number of moles of glycerin = 27.2g / 92 g/mol = 0.29565

total number of moles = 7.33333 moles + 0.29565 moles = 7.62898 moles

=> X solv = 7.33333 / 7.62898 = 0.96125

=> p = 0.96125 * 31.8 torr ≈ 30.57 torr ≈ 30.6 torr.

Answer: 30.6 torr

[ad_2]

Categories
Assignment Help

Fined the volume of the solid in cubic millimeters

[ad_1]

Solution:

The Given Rectangle having dimensions

Length = 80 cm

Breadth = 50 cm

Let the Six squares which has been cut from this rectangle have side of length a cm.

Area of each square = (Side)²= a²

Area of 6 Identical Squares = 6 × a²= 6 a²

If four squares are cut from four corners and two along Length,

then , Length of Box = (80 – 3 a)cm, Breadth of Box = (50 – 2 a)cm, Height = a cm

Volume of Box =V = Length × Breadth × Height

    V = (80 – 3 a)× (50 – 2 a)× a

     V   = 4000 a – 310 a² + 6 a³

For Maximum Volume

V’= 0 , where V’ = Derivative of V with respect to a.

V’= 4000 – 620 a + 18 a²

V’ =0

18 a² – 620 a + 4000= 0

9 a² – 310 a + 2000=0

using determinant method

a = frac{310pmsqrt{96100-72000}}{18}=frac{310pm155}{18}=frac{310-155}{18}=8.6 cm

V”=1 8 a – 310 = -ve

which shows , when a = 8.6 cm , volume is maximum.

So, V = 4000×8.6 – 310×(8.6)²+6×(8.6)³=15288.736 cm³

OR

If four squares are cut from four corners and two along Breadth,

then , Length of Box = (80 – 2 a)cm, Breadth of Box = (50 –  3 a)cm, Height = a cm

Volume of Box =V = Length × Breadth × Height

    V = (80 – 2 a)× (50 – 3 a)× a

     V   = 4000 a – 340 a² + 6 a³

For Maximum Volume

V’= 0 , where V’ = Derivative of V with respect to a.

V’= 4000 – 680 a + 18 a²

V’ =0

18 a² – 680 a + 4000= 0

9 a² – 340 a + 2000=0

Using Determinant method

a = frac{340pmsqrt{115600-72000}}{18}=frac{340pm209}{18}=frac{131}{18}=7.6 cm

V”=18 a -340= -ve value when a = 7.6 cm, shows volume is maximum when a = 7.6 cm

V= 4000×7.6 -340 × (7.6)² +6× (7.6)³=13395.456 cubic cm

[ad_2]

Categories
Assignment Help

Find the volume v of the described solid s. the base of s is a circular disk with radius 5r. parallel cross-sections perpendicular to the base are squares.

[ad_1]

Find the volume v of the described solid s. the base of s is a circular disk with radius 5r. parallel cross-sections perpendicular to the base are squares.

[ad_2]

Categories
Assignment Help

Given that mass was lost from the copper (ii) carbonate hydroxide hydrate during heating, in this decomposition reaction, how many moles of solid product were produced? the molar mass of the solid product is 79.545 g/mol (number of moles = mass (g) / molar mass (g/mol)).

[ad_1]

This problem is to apply Roult’s Law.

Roult’s Law states that the vapor pressure, p, of a solution of a non-volatile solute is equal to the vapor pressure of the pure solvent, Po solv, times the mole fraction of the solvent, Xsolv

p = Xsolv * Po sol

X solv = number of moles of solvent / number of moles of solution

The solvent is water and the solute (not volatile) is glycerin.

Number of moles = mass in grams / molar mass

mass of water = 132 ml * 1 g/ml = 132 g

molar mass of water = 18 g/mol

=> number of moles of water = 132 g / 18 g/mol = 7.33333 mol

mass of glycerin = 27.2 g

molar mass of glycerin:, C3H8O3: 3 * 12 g/mol + 8 * 1 g/mol + 3*16 g/mol = 92 g/mol

number of moles of glycerin = 27.2g / 92 g/mol = 0.29565

total number of moles = 7.33333 moles + 0.29565 moles = 7.62898 moles

=> X solv = 7.33333 / 7.62898 = 0.96125

=> p = 0.96125 * 31.8 torr ≈ 30.57 torr ≈ 30.6 torr.

Answer: 30.6 torr

[ad_2]

Categories
Assignment Help

According to Le Chatelier’s principle, a change in pressure affects the chemical equilibrium of the reaction system under what condition? The reactants and the products are in the solid phase. The reactants and the products are in the liquid phase. Some of the reactants or the products are in the gaseous phase. Some of the reactants or the products are solid, and some are liquid.

[ad_1]

This problem is to apply Roult’s Law.

Roult’s Law states that the vapor pressure, p, of a solution of a non-volatile solute is equal to the vapor pressure of the pure solvent, Po solv, times the mole fraction of the solvent, Xsolv

p = Xsolv * Po sol

X solv = number of moles of solvent / number of moles of solution

The solvent is water and the solute (not volatile) is glycerin.

Number of moles = mass in grams / molar mass

mass of water = 132 ml * 1 g/ml = 132 g

molar mass of water = 18 g/mol

=> number of moles of water = 132 g / 18 g/mol = 7.33333 mol

mass of glycerin = 27.2 g

molar mass of glycerin:, C3H8O3: 3 * 12 g/mol + 8 * 1 g/mol + 3*16 g/mol = 92 g/mol

number of moles of glycerin = 27.2g / 92 g/mol = 0.29565

total number of moles = 7.33333 moles + 0.29565 moles = 7.62898 moles

=> X solv = 7.33333 / 7.62898 = 0.96125

=> p = 0.96125 * 31.8 torr ≈ 30.57 torr ≈ 30.6 torr.

Answer: 30.6 torr

[ad_2]

Categories
Assignment Help

According to Le Chatelier’s principle, a change in pressure affects the chemical equilibrium of the reaction system under what condition? The reactants and the products are in the solid phase. The reactants and the products are in the liquid phase. Some of the reactants or the products are in the gaseous phase. Some of the reactants or the products are solid, and some are liquid.

[ad_1]

This problem is to apply Roult’s Law.

Roult’s Law states that the vapor pressure, p, of a solution of a non-volatile solute is equal to the vapor pressure of the pure solvent, Po solv, times the mole fraction of the solvent, Xsolv

p = Xsolv * Po sol

X solv = number of moles of solvent / number of moles of solution

The solvent is water and the solute (not volatile) is glycerin.

Number of moles = mass in grams / molar mass

mass of water = 132 ml * 1 g/ml = 132 g

molar mass of water = 18 g/mol

=> number of moles of water = 132 g / 18 g/mol = 7.33333 mol

mass of glycerin = 27.2 g

molar mass of glycerin:, C3H8O3: 3 * 12 g/mol + 8 * 1 g/mol + 3*16 g/mol = 92 g/mol

number of moles of glycerin = 27.2g / 92 g/mol = 0.29565

total number of moles = 7.33333 moles + 0.29565 moles = 7.62898 moles

=> X solv = 7.33333 / 7.62898 = 0.96125

=> p = 0.96125 * 31.8 torr ≈ 30.57 torr ≈ 30.6 torr.

Answer: 30.6 torr

[ad_2]

Categories
Assignment Help

Instructions:Select the correct answer. Why does a solid change to liquid when heat is added? A-The spacing between particles decreases. B-Particles lose energy. C-The spacing between particles increases. D-The temperature decreases.

[ad_1]

There are two systems in the human body that are responsible for the coordination between the functions of different systems to achieve the unity of the living organism’s body. These two systems are the nervous system and the endocrine system. The action of the nervous system is fast and takes a short time, while the action of the endocrine system is slow and takes a long time.

The functional unit of the nervous system is the nerve cell or the neuron. The neuron consists of a cell body and the axon. The cell body starts with the dendrites that receive the messages or the impulses from other neurons or from different sense organs or receptors. These impulses are then transmitted through the cell body. The cell body contains a nucleus and different organelles which help the nerve cell to perform its functions. The nerve impulse is then transmitted to the axon.

The axon is an extension from the cell body. There are some cells called Schwan cells that secrete a myelin sheath to insulate the axon from the surrounding medium. The insulated axons have more ability to conduct the impulses than non-insulated axons. The axon ends with the terminal arborizations. The terminal arborizations of a nerve cell connect to the dendrites of the next cell or to the afferent organ. The gaps between the dendrites and the terminal arborizations are called the synapses.

The nerve impulse is an electrochemical phenomenon i.e. an electrical phenomenon with a chemical nature. The membrane of the axon acts as a barrier between an outside positively charged medium and an inside negatively charged medium. This makes a potential difference of  -70mV. This state is called the resting potential. When the membrane is subjected to a stimulus, the positive charges enter to inside and the negative charges exit to the outside. The potential difference now becomes +40mV. This state is called the depolarization state. The point of stimulation acts as a new stimulus for the next point and so on. The membrane sooner gains its permeability again and the positive charges return to the outside and the negative charges to inside. This state is called repolarization.

The nerve impulse reaches the synapse. There are some neurotransmitters that are excited by the nerve impulse coming and carry the message across the membrane. Some receptors receive theses neurotransmitters on the dendrites of the next neuron. These receptors act as a stimulus for the new cell.

[ad_2]

Categories
Assignment Help

What state of matter has a fixed volume and a fixed shape A. liquid B. gas C. plasma D. solid

[ad_1]

Answer: The correct answer is all of these.

Explanation:

Organic compounds are defined as the chemical compounds where one or more carbon atoms are covalently bonded to other atoms of hydrogen, oxygen or nitrogen.

They occur naturally in nature and the main sources of these organic compounds are petroleum, coal and natural gases.

Petroleum are the naturally occurring substances which contain organic compounds in the form of gases, liquid or semi-solid. Thus, they are a major source of organic compound.

Coal is also a form of fossil fuel which are the major source of organic compound.

Natural gas contains hydrocarbons and also is the major source of organic compounds.

Thus, the correct answer is all of these.

[ad_2]

Categories
Assignment Help

Aqueous magnesium chloride and hydrogen gas are produced when solid magnesium reacts with aqueous hydrochloric acid (HCl). What is the equation for this reaction? Do not worry about balancing this equation.

[ad_1]

Explanation :

In the net ionic equations, we are not include the spectator ions in the equations.

Spectator ions : The ions present on reactant and product side which do not participate in a reactions. The same ions present on both the sides.

(a) The given balanced ionic equation is,

Ni(NO_3)_2(aq)+Na_2S(aq)rightarrow NiS(s)+2NaNO_3(aq)

The ionic equation in separated aqueous solution will be,

Ni^{2+}(aq)+2NO_3^-(aq)+2Na^+(aq)+S^{2-}(aq)rightarrow NiS(s)+2Na^+(aq)+2NO_3^-(aq)

In this equation, Na^+text{ and }NO_3^- are the spectator ions.

By removing the spectator ions from the balanced ionic equation, we get the net ionic equation.

The net ionic equation will be,

Ni^{2+}(aq)+S^{2-}(aq)rightarrow NiS(s)

(b) The given balanced ionic equation is,

NaNO_3(aq)+KBr(aq)rightarrow KNO_3(s)+NaBr(aq)

The ionic equation in separated aqueous solution will be,

Na^+(aq)+NO_3^-(aq)+K^+(aq)+Br^-(aq)rightarrow KNO_3(s)+Na^+(aq)+Br^-(aq)

In this equation, Na^+text{ and }Br^- are the spectator ions.

By removing the spectator ions from the balanced ionic equation, we get the net ionic equation.

The net ionic equation will be,

NO_3^-(aq)+K^+(aq)rightarrow KNO_3(s)

(c) The given balanced ionic equation is,

Li_2SO_4(aq)+BaCl_2(aq)rightarrow BaSO_4(s)+2LiCl(aq)

The ionic equation in separated aqueous solution will be,

2Li^+(aq)+SO_4^{2-}(aq)+Ba^{2+}(aq)+2Cl^-(aq)rightarrow BaSO_4(s)+2Li^+(aq)+2Cl^-(aq)

In this equation, Li^+text{ and }Cl^- are the spectator ions.

By removing the spectator ions from the balanced ionic equation, we get the net ionic equation.

The net ionic equation will be,

SO_4^{2-}(aq)+Ba^{2+}(aq)rightarrow BaSO_4(s)

[ad_2]

Categories
Assignment Help

The phase change in which a substance changes from a liquid to a solid is A. freezing. B. melting. C. sublimation. D. condensation.

[ad_1]

The formula for freezing point depression is:

ΔT = Kf * m         —>1

Where,

ΔT = change in temperature = 2.88 degrees Celcius

Kf = freezing point molar constant of solvent

m = molality (moles solute/mass solvent)

First we calculate for molality since we are given the mass
of solute and solvent.

Molar mass of pentane = 72.15 g / mol

molality m= (0.123 g / 72.15 g / mol) / (2.493 x 10^-3 kg)

m = 0.684 molal

Going back to equation 1:

ΔT = Kf * m

2.88 = Kf * 0.684

Kf = 4.21 degC / molal

 

Value for Kf in question 1 given that m = 0. 829
mol/kg:

2.88 = Kf * 0.829

Kf = 3.47 degC / molal

[ad_2]

Categories
Assignment Help

Which of the following describes an insulator? A.Does not allow electrons to move through it B.Allows electrons to move through it C.Is always a solid D.Is always a gas

[ad_1]

There are two systems in the human body that are responsible for the coordination between the functions of different systems to achieve the unity of the living organism’s body. These two systems are the nervous system and the endocrine system. The action of the nervous system is fast and takes a short time, while the action of the endocrine system is slow and takes a long time.

The functional unit of the nervous system is the nerve cell or the neuron. The neuron consists of a cell body and the axon. The cell body starts with the dendrites that receive the messages or the impulses from other neurons or from different sense organs or receptors. These impulses are then transmitted through the cell body. The cell body contains a nucleus and different organelles which help the nerve cell to perform its functions. The nerve impulse is then transmitted to the axon.

The axon is an extension from the cell body. There are some cells called Schwan cells that secrete a myelin sheath to insulate the axon from the surrounding medium. The insulated axons have more ability to conduct the impulses than non-insulated axons. The axon ends with the terminal arborizations. The terminal arborizations of a nerve cell connect to the dendrites of the next cell or to the afferent organ. The gaps between the dendrites and the terminal arborizations are called the synapses.

The nerve impulse is an electrochemical phenomenon i.e. an electrical phenomenon with a chemical nature. The membrane of the axon acts as a barrier between an outside positively charged medium and an inside negatively charged medium. This makes a potential difference of  -70mV. This state is called the resting potential. When the membrane is subjected to a stimulus, the positive charges enter to inside and the negative charges exit to the outside. The potential difference now becomes +40mV. This state is called the depolarization state. The point of stimulation acts as a new stimulus for the next point and so on. The membrane sooner gains its permeability again and the positive charges return to the outside and the negative charges to inside. This state is called repolarization.

The nerve impulse reaches the synapse. There are some neurotransmitters that are excited by the nerve impulse coming and carry the message across the membrane. Some receptors receive theses neurotransmitters on the dendrites of the next neuron. These receptors act as a stimulus for the new cell.

[ad_2]