The correct statement is that metals are shiny, hard, malleable, and have a high melting point. This accurately describes the physical properties of metals, distinguishing them from non-metals.

Salt water is more dense than fresh water, which allows your body to float more easily in sea water. This increased buoyancy makes swimming in the ocean easier compared to a lake.

Gasoline has a lower density than ammonia, glycerine, and water. This makes it the least dense liquid among the options provided.

Ammonia has a density of about 0.73 g/cm³, which is higher than gasoline (approximately 0.7 g/cm³). Therefore, the correct statement is that ammonia is higher than gasoline.

State A is a solid because solids have particles that are closely packed together, giving them a definite shape and volume. In contrast, liquids and gases have particles that are more spread out.

Gases fill their containers because their molecules are loosely packed. This allows them to move freely and occupy the entire volume of the container, unlike solids or liquids where molecules are tightly packed.

A liquid has a definite volume but takes the shape of its container, making it distinct from solids, which have a fixed shape, and gases, which have neither a fixed shape nor volume.

Metals are commonly used to create alloys, which are mixtures of two or more metals that enhance properties like strength and durability. This makes 'Alloys in metal' the correct choice for common metal uses.

Rare earth elements are essential for producing strong magnets, which are used in various applications like electric motors and hard drives. While they have roles in other areas, their primary significance lies in magnet production.

The density of salt water is greater than fresh water, causing the carrot to float in salt water. The carrot's density is greater than fresh water but less than salt water, explaining its behavior in both solutions.