Common Chemical Compounds and Reactions

This option is correct because the crystal of sodium carbonate are exposed to air to form a fine powder in which nine water molecules are exposed to air. It gives monohydrated sodium carbonate. These types of crystal are called as efflorescence.

Agar is more often used solidifying agent in culture media. It melts completely at the temperature of boiling water (97-100^oC) and solidifies when cooled to about 45^oC. It is chemically polysaccharide and is not attacked by bacteria and others microbes growing on it. Agar is obtained from seaweeds(Algae) called kelps.

NaCl is sodium chloride. It is the common salt that we use for cookoing.

It is a mixed salt. Salt that contains more than one acid radical or basic radical is called as mixed salt. Other examples are bleaching powder ;Ca(OCl) and sodium potassium sulphate;NaKSO_4.

NaOH is a strong base and it is used in many industries, mostly as a strong chemical base in the manufacture of textiles, drinking water and soaps. 

Iodine sublimes and directly changes into gas when heated.

It is the chemical name of salt.

It is insoluble in water.

Silver bromide is a light-sensitive chemical used in traditional photographic films and papers to capture images. When exposed to light, it undergoes a chemical reaction that creates a latent image. Sodium chloride and aluminum hydroxide do not have the necessary light-sensitive properties for this application.

Baking soda is the common name for sodium bicarbonate, which has the chemical formula NaHCO3. Sodium carbonate (Na2CO3) is known as washing soda.

Both water and ammonia have fixed composition.

Air is a homogeneous mixture of many gases.

This option is correct because the barium is reacting with water to formed barium hydroxide. This is called baryta water.

This option is correct, because plaster of paris when heated above 200^oC is converted in to anhydrous calcium sulphate. This anhydrous is known as dead burnt. Because it does not set like plaster of paris when moistened with water.