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Illusion [34]
3 years ago
15

Classify the following changes as physical or chemical changes. a. Water boils. b. Salt dissolves in water c. Milk turns sour d.

A metal rusts.
Chemistry
1 answer:
geniusboy [140]3 years ago
6 0

Answer:

Water boils - physical change

Salt dissolves in water- chemical change

Milk turns sour- chemical change

metal rusts - chemical change

Explanation:

A chemical change refers to changes that are irreversible and the process involves the evolution of heat along with the formation of a new substance, examples include;Salt dissolves in water, Milk turns sour, metal rusts etc

The boiling of water is a physical change. The water can be cooled and the vapour condensed,hence, the boiling of water is a physical change.

Physical changes are easily reversible and no new substance is formed.

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Match each term to its meaning. (3 points)
fenix001 [56]

Answer:

1-b 2-c 3-a

Explanation:

6 0
3 years ago
Read 2 more answers
Drag each item to indicate whether it is related to Aristotle's or Ptolemy's model of the solar system, or to both. Some items m
Romashka-Z-Leto [24]

Answer:

<u>Aristotle's Model :</u>

geocentric

planets fixed on nested spheres

<u></u>

<u>Ptolemy's model:</u>

geocentric

planets fixed on epicycles

accurately predicted the positions of the planets

Explanation:

Let's begin by the fact both models are geocentric  and make a brief explanation of them:

<u></u>

<u>Aristotle's Model :</u>

Aristotle built his model based on observations and philosophical assumptions, not on measurements or calculations, then he mistakenly thought the Earth was the center of the universe.

So, according to this model, the universe was spherical and finite, with the Earth immobile at its center, composed of the four fundamental elements (made up of spherical layers): <em>ground, water, air and fire</em>; and the Sun along with the fixed planets in their respective concentric spheres (also called nested spheres) revolving around the Earth.

<u>Ptolemy's model:</u>

Ptolemy's model of the universe was also geocentric, placing the Earth motionless in the center of the known universe and was the accepted model for a long time during the Middle Ages.

In this sense, ccording to Ptolemy's model of the universe our planet remains stationary while the other planets, the Moon and the Sun describe complicated orbits around it (called epicycles).

However, this model predicted with an acceptable accuracy for that time the motion of the known planets, until Copernicus appeared with the revolutionary Heliocentric model.

5 0
3 years ago
Explain the three types of cumbusion ??​
Alik [6]

Answer:

Complete Combustion

One of the types of combustion is Complete Combustion. Complete combustion occurs in an unlimited supply of air, oxygen in particular. Also, complete combustion is also known as clean combustion. Here the hydrocarbon will burn out completely with the oxygen and leave only two byproducts, water, and carbon dioxide.

An example of this is when a candle burns. The heat from the wick will vaporize the wax which reacts with the oxygen in the air. The two products of the reaction are water and carbon dioxide. In an ideal situation all the wax burns up and complete combustion takes place

2] Incomplete Combustion

Incomplete combustion takes place when the air is in limited supply. And as opposed to complete combustion it is otherwise known as dirty combustion. Due to lack of oxygen, the fuel will not react completely. This, in turn, produces carbon monoxide and soot instead of carbon dioxide.

An example is burning of paper. It leaves behind ash (a form of soot) as a byproduct. In a complete combustion, the only products are water and carbon dioxide. Also, incomplete combustion produces less energy than complete combustion.

3] Rapid Combustion

Another type of combustion is Rapid Combustion. Rapid energy needs external heat energy for the reaction to occur. The combustion produces a large amount of heat and light energy and does so rapidly. The combustion will carry on as long as the fuel is available.

An example is when you light a candle. The heat energy is provided when we light the candle with a matchstick. And it will carry on till the wax burns out. Hence it is a rapid combustion

4] Spontaneous Combustion

As the name suggests the combustion occurs spontaneously. This means that it requires no external energy for the combustion to start. It happens due to self-heating. A substance with low-ignition temperatures gets heated and this heat is unable to escape.

The temperature rises above ignition point and in the presence of sufficient oxygen combustion will happen. The reaction of alkali metals with water is an example.

5] Explosive Combustion

Explosive Combustion happens when the reaction occurs very rapidly. The reaction occurs when something ignites to produce heat, light and sound energy, The simple way to describe is it to call it an explosion. Some classic examples are firecrackers or blowing up of dynamite.

6 0
3 years ago
what happens when baking soda is mixed with vinegar a a new substance is formed B the substances are the same c but the baking s
Ray Of Light [21]

Answer:

NaHCO3 sodium bicarbonate is baking soda; added to the acetic acid, it forms sodium acetate (aqueous), CO2 gas & water. Remove the water & solid sodium acetate remains.

Explanation:

5 0
3 years ago
Which of the following statements are TRUE for BOTH oxygen and sulfur atoms?
irina1246 [14]

Answer:

b. have the same kind number of complete shells

4 0
2 years ago
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