States of Matter

Eosin methylene blue agar and hektoen enteric agar are the correct examples of a Selective and differential media.

Water is a compound (H2O) with fixed chemical composition. Air is a mixture of several gases (nitrogen, oxygen, carbon dioxide, etc.) that are not chemically combined and can vary in proportion. This is the correct analogy: water:compound::air:mixture.

When warm air containing water vapor comes in contact with a cool surface, condensation occurs. This phase change from gas (water vapor in air) to liquid (water droplets) is the same process that causes dew to form on grass or water droplets on cold drinks.

Changing of water vapour into water is called condensation.

The melting of an ice candy is a reversible change because ice candy melts due to increased temperature (room temp).

When a state change occurs from solid to liquid, particles gain energy.

because plaster of Paris has a property of setting into a hard mass on getting mixed with water due to the formation of a new compound. The hard mass cannot be converted back into the previous plaster of Paris.

Changes that can be reversed is called reversible changes.

Air is a mixture of gases, primarily nitrogen (78%), oxygen (21%), and trace gases like argon, carbon dioxide, and water vapor. A mixture can be separated by physical means, unlike a compound which has fixed chemical bonding. The composition of air varies slightly with location and altitude, confirming it's a mixture rather than a compound.

The chemical reactions in all plants and animals that support life take place in as water medium. Water not only provides medium to make these reactions possible but is itself an important reactant or product of these reactions. Water is thus an important universal solvent. It consists of 2 hydrogen atoms and one oxygen atom which are held together by covalent bonds. Oxygen is more electronegative than hydrogen molecules. Hydrogen is positively charged and oxygen is negatively charged. Thus it can dissolve and dissociate most of the compounds. Positive part will be attracted towards oxygen and negative part of the compound towards hydrogen.

Condensation is process in which water vapours present in atmosphere are changed or cooled down to form water droplets. These water droplets combine together to form clouds. Thus clouds are composed of millions of little droplets of water.

Water drops appear on the outer surface of glass containing cold water. The cold surface of the glass containing cold water cools the air around it, and the water vapour of the air condenses to form water droplets on the surface of the glass. Thus, it is a process of change of gaseous state into liquid state.

All the choices given i.e. evaporation, transpiration and condensation are natural phenomena. Crystallization is a process of formation of crystals by boiling a liquid and then cooling it until gets solidify into a crystalline solid either by natural process or artificially. Ice crystals are formed naturally by the freezing of water. So crystallization is an artificial process.

The boiling point of a liquid is the temperature at which its vapor pressure equals the surrounding atmospheric pressure. By decreasing the external pressure, less vapor pressure is needed for the liquid to boil, thereby reducing its boiling point.

Milk is an emulsion - specifically, it's an oil-in-water emulsion where fat globules are dispersed in water. Emulsions are colloidal systems where one liquid is dispersed as droplets in another immiscible liquid, stabilized by emulsifying agents like casein proteins in milk.