Questions

Dust particles such as coal dust(smoke) are fine particle of a solid (carbon in the case of smoke) dispersed in air. They are colloidal systems and the particles are charged either positive or negative. In an applied electrical field, they are attracted towards the opposite electrodes. Movement of the particles towards the electrodes is known as 'electrophoresis'. Hence electrophoresis is applied to remove smoke within the chimeny itself without allowing it to escape into the air and cause nuisance.

Dull means not sharp, not shining, not bright, ...

Hence, the given words are all that means the opposite of dull.

The Study of Blood is called as Hematology which involves treating diseases that affect the production of blood and its components, such as bloodcells, hemoglobin, blood proteins, bone marrow, platelets, blood vessels, spleen, and the mechanism of coagulation.

A typical giraffe neck can stretch as long as six feet, the giraffe's tongue usually measures 18-20 inches long.

Why that much long:

Giraffe's eat Acacia tree leaves. The acacia tree's tasty leaves are protected by very sharp thorns. The giraffe's long tongue allows it to reach the highest, tastiest leaves while avoiding the sharp thorns. Its tongue also features a thick, tough layer that protects it from being cut by the thorns. If a giraffe's tongue does get cut by a thorn, its extra-thick saliva has antiseptic properties that help it to heal quickly.