States Of Matter ( Grade 9c)

Explanation
The statement is referring to the compressibility of different states of matter. In general, gases are compressible because their particles are far apart and can be easily compressed closer together. On the other hand, liquids and solids have particles that are already close together, making them less compressible. Therefore, the correct answer is gas, as it is the only state of matter that is compressible.

Explanation
The process of changing from a solid state to a liquid state is called melting. This occurs when heat is applied to a solid substance, causing the particles to gain energy and move more rapidly, eventually breaking the bonds that hold them together in a solid structure. As a result, the substance transitions into a liquid state, where the particles are able to move freely and flow.

Explanation
During the melting of ice, the temperature remains constant at 0 degrees Celsius. This is because the energy being added to the ice is being used to break the intermolecular bonds between water molecules, rather than increasing the temperature. Once all the ice has melted, the temperature can start to increase again.

Explanation
The condensation of vapor is exothermic because it releases heat energy to the surroundings. When vapor cools down and changes into a liquid state, the molecules lose energy and slow down, resulting in the release of heat. This process is commonly observed when steam condenses into water droplets on a cold surface, such as a mirror or a window. The heat released during condensation is the reason why clouds form and rain falls in the water cycle.

Explanation
Particles are close to each other in solid and liquid states. In a solid, particles are tightly packed and have a fixed position, resulting in a rigid structure. In a liquid, particles are also close together but have more freedom to move around, allowing the liquid to flow and take the shape of its container. In a gas, particles are far apart and have a lot of freedom to move, resulting in a lack of definite shape or volume.

Explanation
At -10oC, oxygen is actually a gas, not a liquid. Oxygen only becomes a liquid at temperatures below -182.96oC. Therefore, the statement is false.

Explanation
When salt is added to water, it increases the boiling point of the water. This is due to a phenomenon called boiling point elevation. Salt molecules disrupt the formation of water vapor bubbles during boiling, requiring the water to reach a higher temperature in order to boil. As a result, the boiling point of the saltwater solution is higher than that of pure water. Therefore, the statement "Adding salt to water increases its boiling point" is true.

Explanation
Tap water does not always boil at 100oC. The boiling point of water depends on various factors such as altitude, impurities in the water, and the presence of dissolved substances. At sea level, pure water boils at 100oC, but at higher altitudes, where the atmospheric pressure is lower, water boils at a lower temperature. Additionally, impurities and dissolved substances can also affect the boiling point of water, causing it to boil at temperatures higher or lower than 100oC. Therefore, the statement that tap water always boils at 100oC is false.