a) DNA & RNA
RNA:
It is single stranded molecule
Contains Ribose sugar
contains adanine, guanine ,cytosine, & uracil bases
generally located in cytoplasm
is of three kinds
DNA:
Double stranded
deoxyribose
contains adanine, guanine cytosine and thymine bases
is of one kind
b) Alloy and Amalgam:
Alloy:
Substance composed of two or more metals. Alloys, like pure metals, possess metallic luster and conduct heat and electricity well, although not generally as well as do the pure metals of which they are formed. Compounds that contain both a metal or metals and certain nonmetals, particularly those containing carbon, are also called alloys. The most important of these is steel. Simple carbon steels consist of about 0.5 percent manganese and up to 0.8 percent carbon, with the remaining material being iron.
Amalgam:
Amalgam is an alloy of mercury with one or more metals.
d) Stars and Planets:
Stars:
Heavenly bodies that shine by its own light and remains relatively fixed in position among the other bodies in the universe.light and energy is generated in a star by the conversion of hydrogen into helium.
Planet: Opaque bodies revolving around the sun in its own orbit & also rotating on its own axis, shines by reflection of the light of other stars( such as sun).
e) Gas and Vapour: The terms vapor and gas can be used interchangeably, although in practice, vapor is used for a substance that is normally in liquid or solid state, such as water, benzene, and iodine. It has been proposed that the use of the term vapor be restricted to a gaseous substance below its critical point; the temperature at which it may be liquefied by the application of sufficient pressure) and the term gas should be used above the critical temperature when the existence of the substance in the liquid or solid state is impossible. This usage is essentially arbitrary because all gaseous substances follow a similar behavior both above and below the critical point.
f) Brass and Bronze: Brass: an alloy of copper and zinc Bronze: an alloy of copper and tin