Crystals that cannot tolerate water include selenite, halite, and pyrite. Selenite is a soft and fragile crystal that can dissolve in water, while halite is a type of salt crystal that will dissolve when exposed to water. Pyrite is a metallic crystal that can rust or tarnish when in contact with water, leading to its deterioration. It is important to keep these crystals dry to maintain their integrity and appearance. **

Air can be compressed because it is a gas and its particles are far apart, allowing them to be pushed closer together. Water, on the other hand, is a liquid with particles that are already close together and have strong intermolecular forces holding them in place. This makes it much more difficult to compress water compared to air. **

Air can be compressed because its molecules are further apart and have more space to move closer together under pressure. Water, on the other hand, is made up of closely packed molecules that are already in a relatively dense state, making it difficult to compress. Additionally, water is considered to be an incompressible fluid due to its high density and strong intermolecular forces, which resist compression. **

Yes, if you cannot answer the safety questions during the practical exam, it is likely that you will fail. Safety is a critical aspect of any practical exam, and not being able to demonstrate knowledge in this area can pose a risk to yourself and others. It is important to study and understand safety protocols before taking any practical exam to ensure a successful outcome. **

Salts can dissolve in water because they are composed of ions that can interact with the polar water molecules through ion-dipole interactions. This allows the water molecules to surround and separate the ions, breaking the ionic bonds holding the salt together. Metals, on the other hand, do not readily dissolve in water because they do not form ions in the same way that salts do. Instead, metals tend to form metallic bonds, which are much stronger and not easily broken by water molecules. **

When water cannot expand when freezing, it creates pressure within its container. This pressure can cause the container to crack or burst, leading to potential damage. It is important to use containers that can withstand this pressure or leave enough space for the water to expand when freezing to prevent any accidents. **

When water cannot expand when it freezes, it exerts pressure on its surroundings. This pressure can cause containers to crack or burst, leading to potential damage. For example, if water in a closed container cannot expand when it freezes, the container may rupture due to the increased pressure. This is why it's important to take precautions to prevent water from freezing in closed containers, such as leaving room for expansion or using containers designed to withstand the pressure. **

The sun cannot be seen at night because the Earth is rotating on its axis, causing the sun to be on the opposite side of the planet. This rotation creates the cycle of day and night. When the sun is on the opposite side of the Earth, it is nighttime for that part of the world, and the sun is not visible from that location. This phenomenon is a result of the Earth's orbit around the sun and its rotation on its axis. **