11. The respiration rate of a goldfish ismeasured. The goldfish is then placed in
cold water and the respiration rate is
measured again.

Activation energy is the energy needed to start a chemical reaction. The correct answer to the given question is option   b. activation energy.

The energy needed to get a reaction started is called the activation energy. It is the minimum amount of energy required for a chemical reaction to occur. Activation energy is needed to break the existing bonds in reactant molecules and form new bonds to produce product molecules.

The correct answer to the given question is option   b. activation energy.

For more such questions on Activation energy, click on:

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The correct matches are as follows:

1. HYDRO POWER: Most common renewable energy source.

Hydro power refers to a type of energy which uses water to produce electricity. This type of energy is derived from the energy of falling water; the energy is used to drive the turbines that generate electricity. The quantity of electricity that can be generated in an hydro power plant depend on the quantity of water available and the height from which the water is falling. Hydro power is a renewable source of energy because of availability of water.

2. SOLAR: Depends on time of day and time of year.

Solar power is the type of electrical power that is derived from the energy of the sun. It is a renewable form of energy and it is considered to be the cleanest and most reliable source of energy. Solar panels are usually used to trap energy from the sun and to convert them to electrical energy. One property of solar power is that, the quantity of solar power that can be obtained depend on the strength of the sun light. On days and time of the year when there is little sunlight, little solar power can only be generated during this time.

3. COAL: Most polluting energy source.

Coal is obtained naturally from underneath the ground through mining. There are different types of coal and these coals were formed millions of years ago. Coal is a non-renewable energy source and is considered to be the most polluting energy source. Burning of coal releases greenhouse gases, which damage the ozone layers. The burning also resulted in production of gases such as carbon monoxide, which brings about acid rain. The extraction of coal also endangered the environment.

4. OIL: Liquid formed from remains of plants and animals.

Crude oil is a natural resource that is obtained from underneath the earth through the process of drilling. Crude oil was formed millions of years ago from the remains of plants and animals. Oil is one of the products that are obtained from the purification of crude oil. Oil is a fossil fuel and it is not renewable. Oil is majorly used to power vehicles and machines. Burning of oil [petrol], results in production of high amount of carbon dioxide and other gases, which pollute the environment.

5. BIOMASS: Renewable source formed from organic material.

Biomass are renewable and energy sources that are formed from organic materials. They are used to create electric power and other forms of power. Examples of materials from which biomass power are derived from are: animal wastes, forest debris, certain waste residues, certain crops and woody fuels. Energy in biomass are released in form of heat when they are burned. The heat is used to power turbines, which generate electricity.

Energy can neither be created nor be destroyed, which can only be transformed into one form or another. The energy obtained from different sources has different properties.

Which of the following energy sources matches correctly with its description?

• Hydropower is the most common renewable energy source, in which water is used to generate electricity. The energy is derived from the use of turbines. It is a renewable source of energy due to the availability of water.

• Solar energy depends on the day and time of the year. Solar energy refers to energy utilized from the sun's rays. The day and time of the year are important in deriving solar energy.

• Coal is the most polluting energy source. It is formed from the remains of fossils billion years ago and produces harmful and toxic gases to the environment when burnt. It is the most common source of air pollution.

• Oil is the liquid produced from the dead remains of plants and animals. It is also referred to as crude oil, which is used as fossil fuel and is not renewable.

• Biomass is a renewable energy source that is produced from organic materials. Electric power can be generated using biomass. Animals' watches, certain residues, and forest debris are the biomass and when burnt produce heat.

Thus, energy is a vital source required to carry out many actions and activities, which can be obtained from different sources.

Learn more about energy sources here:

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Answer:

0.22 grams of magnesium

This seems too low, so check the calculations/

Explanation:

How is the heat delivered?  Is the magnesium hot and added to the water?  If so, at what temperature.

Is the heat generated from an exothermic chemical reaction?

=================

I'll assume here that the heat comes from the reaction of magnesium with water.  The balanced equation is:

   Mg + 2H2O = Mg(OH)2 + H2

It has a heat of reaction of  −924.7 kJ/mol.

We need enough Mg to heat 30 ml of water from 22°C to 90°C.  The specific heat of water is needed.  It is 4.184 J/g-K.  It tells us that 4.184 Joules are needed to raise the temperature of water by 1 degree K.

30 ml of water with density 1 gram/ml means we have 30 grams of water.  (We'll ignore the water that is added from the chemical reaction.).

Lets calculate the Joules required to raise 30 grams of water from 22°C to 90°C.  Note that the specific heat has units of g and Kelvin.  Since we need a temperature change, the number value for ΔT is the same for both °C and °K.  So the temperature change is +68°K.

We can now calculate the Joules required:  

(30 grams H2O)*(4.184 J/g-K)*(+68°K)  = 8535.4 Joules or 8.5 kJ to 2 sig figs.

The Mg/H2O  heat of reaction of  −924.7 kJ/mol. will allow us to calculate the amount of Mg needed to supply 8.5 kJ.  The minus sign tells us that the reaction RELEASES energy (the energy leaves the "system" of Mg and H2O).  

Calculate the moles of Mg needed to release 8.5 kJ:

   (924.7 kJ/mole)*(x moles) = 8.5 kJ

x moles = 0.0092 moles

Whoa.  That is only (0.0092 moles)*(24.03 g/mole) = 0.22 grams of magnesium

This seems low to me, so check on the heat of reaction figure I used.  And don't let the hydrogen get away.  

Answer:

1. gold and rust

2. carbon dioxide

3. sea water

4. carbon

Answer:

1. Gold and Iron

2. Helium

3. Seawater

4.Rust

Explanation:

The experiment that used alpha particles to bombard a thin sheet of gold foil indicated that most of the volume of the atoms in the foil is taken up by

Further Explanation:

Rutherford’s experiment:

Rutherford's model of atom is the classic model of the atom instead of having many limitations. He designed an experiment that used alpha particles emitted by radioactive elements as objects that can demonstrate the structure of the atom. Rutherford showed his own physical model for the subatomic structure as a result of the experimental observations.

The postulates of Rutherford’s model are as follows:

1. An atom consists of a positive charge in a very small volume. Most of its mass is concentrated in a very small region of the atom and this region was termed as the nucleus of the atom.

2. The nucleus of the atom is surrounded by the negatively charged particles which were called electron. These electrons were supposed to revolve around the atomic nucleus in a circular path at a very high speed. This circular path is called orbit.

3. A very strong electrostatic force of attraction holds together the negatively charged electrons revolving around the nucleus positively charged concentrated in the nucleus.

Limitations of Rutherford’s model:

1. It did not tell anything about the distribution of electrons in various orbits.

2. This model failed to explain Maxwell’s theory of electromagnetic radiation.

3. It was unable to explain the stability of an atom.

Therefore most of the volume of an atom is taken up by empty space in the atom.

Learn more:

1. The major contribution of Antoine Lavoisier to chemistry: brainly.com/question/2500879

2. Example of physical change: brainly.com/question/1119909

Answer details:

Grade: High School

Subject: Chemistry

Chapter: Atomic Structure

Keywords: Rutherford, atom, volume, nucleus, orbit, postulates, limitations, Maxwell, electromagnetic radiations, distribution of electrons, stability of atom.