Question

state the difference between:
(a) Convection and conduction
(b) Physical and chemical change
(c) autotrophic nutrition and heterotrophic nutrition
(d) cutting of paper and burning of paper

Answer 1

A; Convection is the transfer of energy by movement of a medium, whereas radiation isthe transfer of energy by, well, thermal radiation. Conduction also requires a medium, but, again, it is a fundamentally different mechanism than either convection or radiation; in this case it is the transfer of energy through a medium.
B; There are several difference between a physical and chemical change  in matter or substances. A physical change in a  substance doesn't change what the substance is. In a physical change where there is a chemical reaction , a new substance is formed and energy is either given off or absorbed.
C; it means that the organism prepare its own food and is not dependent on any other organism. 1) it means that the organism does not prepare its own food and dependent on other organism for food. 2) food is prepared from co2 ,water,sunlight.
D; Tearing of a paper is  a physical change because when the paper is  torn only the appearance of the paper is changed and no new substance is  formed. ... Hence compared burning of paper is  a chemical change and tearing of paper is  physical change.

Answer 2

a) Convection takes place in liquids and gases. It is a modern transfer of heat in liquids and gases from one part fluid to another by the movement of particles.
Conduction takes place in solids .It is a modexcellent of transfer of heat in solids by which heat flows from hotter end to the colder end.
b) Physical change is a change in which none new substance is formed. It may undergo in shape , size and state.
Chemical changet is a change in which a new substance is formed.It is usually irreversible change.
c)