O A physical change does not change the chemical formula of the substance
O A physical change has similar characteristics as a chemical change.
A physical change is a change in how the substances react with other substances.
The correct answer is physical change does not change the chemical formula of the substance.
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Answer:
B. a physical change does not change the chemical formula of the substance
Explanation:
Physical change does not change the substance or identity of an object
Answer:
According to collision theory, to preventing a dangerous reaction from occurring, the best is to keep reactants in separate containers (last statement).
Justification:
Collison theory states that the the reactant substances (atoms, ions or molecules) must first collide to react and form the products.
Additionally, to form the products, the collisions must meet two requirements:
Hence, the collision theory permits youpreventing a dangerous reaction from occurring, by using the elemental knowledge that the substances must first collide in order to they react, and so the most effective way is to keep the reactants in separate contaners, preventing the reactants from coming into direct contact.
Answer: Option (d) is the correct answer.
Explanation:
According to collision theory, the particles should colloid frequently and they should be placed in proper orientation.
Whereas sometimes even at low temperature, reactant particles have enough energy. As a result, they tend to colloid or react with each other. Hence, it leads to a chemical reaction which might be dangerous.
Therefore, it is suitable to keep the reactant particles in separate containers so that a chemical reaction cannot take place.
So, we can conclude that the statement keep the reactants in separate containers best applies collision theory to preventing a dangerous reaction from occurring.
Elements and compounds are types of mixtures.
Pure substances are made up of mixtures combined in specific ratios.
Mixtures are classified based on the distribution of particles in them.
Answer: Option (d) is the correct answer.
Explanation:
When two or more different substances are mixed together then it results in the formation of a mixture.
Mixture are of two types, that is, homogeneous mixture and heterogeneous mixture.
In homogeneous mixture, the constituent particles are distributed evenly throughout the mixture.
Whereas in heterogeneous mixture, the constituent particles are non-uniformly distributed.
Thus, we can conclude that mixtures are classified based on the distribution of particles in them.
(2) ethanol (4) water
The compound that has the lowest vapor pressure is ethanoicacid. The correct option is 1.
Vapor pressure is a measure of a material'stendency to change into a gaseous or vapor state, and it rises with temperature.
The boilingpoint of a liquid is the temperature at which the vapor pressure at its surface equals the pressure exerted by its surroundings.
A liquid with weak intermolecularforces evaporates faster and has a higher vapor pressure. A liquid with stronger intermolecular forces is more difficult to evaporate and thus has a lower vapor pressure.
At 50°C, ethanoloicacid has the lowest vapor pressure, which is 0.08 atm. Propanone has a vapor pressure of 0.84 atm at 50°C. At 50°C, ethanol has a vapor pressure of 0.30 atm.
Thus, the correct option is 1.
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Answer : Option A) Ethanoic Acid
Explanation : Ethanoic acid has the lowest vapor pressure i.e 0.08 atm at the temperature of 50°C compared to the other given options.
The vapour pressure of propanone at 50°C is 0.84 atm
Ethanol has vapour pressure as 0.30 atm at 50°C
water has vapour pressure of 0.12 atm at 50°C.
Answer:
1. Sand Casting: Sand casting is a popular method used to create pewter objects. Here's how it's achieved:
- First, a pattern or model of the desired object is created using materials like wood, plastic, or metal.
- The pattern is then pressed into a special type of sand called green sand, leaving an impression.
- Next, the pattern is removed, leaving a cavity in the sand.
- Molten pewter is poured into the cavity and left to cool and solidify.
- Once cooled, the sand is carefully removed, revealing the pewter object.
2. Spin Casting: Spin casting, also known as centrifugal casting, is another way to mold pewter. Here's how it works:
- A rubber mold of the object is created, usually using a master pattern made of wax or another material.
- The rubber mold is placed in a casting machine that rotates at high speed.
- Molten pewter is poured into the mold while it spins.
- The centrifugal force evenly distributes the pewter, filling the mold's cavities.
- As the pewter cools, it solidifies and takes the shape of the mold.
- Once cooled, the mold is opened, and the pewter object is removed.
3. Die Casting: Die casting is a method used for producing high-quality pewter objects. Here's how it's done:
- A metal mold, called a die, is created to match the desired shape of the object.
- Molten pewter is injected into the die under high pressure.
- The pressure ensures that the pewter fills the mold completely and captures all the intricate details.
- After a short cooling period, the die is opened, and the pewter object is ejected.
Explanation:
These are just a few ways to form or mold pewter. Each method has its advantages and is suitable for different types of objects. It's important to choose the appropriate method based on the complexity of the design and the desired quality of the final product.