Production function of a firm is a functional relationship between inputs used and output produced by the firm. Returns to a factor relate to the short period production function when one factor is varied keeping the other factor fixed in order to have more output

Human wants to refer to our desire for goods and services and for which we have the ability to buy. Human wants are unlimited, whereas the means to satisfy these wants are not only limited but have alternate uses also. The Scarcity of resources is one of the main reasons for all economic problems. Since the resources to satisfy our wants are limited, i.e. the supply of these resources are less as compared to their demand,  we have to choose the best alternative to which these resources can be put. In other words, we have to decide which wants are to be fulfilled by utilising the given resources for choosing, we can rank the wants according to our priorities. The want which appears high on the priority list and for which we have the ability to pay will be first chosen to be satisfied.

Budget line is a graphical representation which shows all the possible combinations of the two goods that a consumer can buy with his given income and market prices of commodities. It is also called consumption possibility line.

Consumer Equilibrium :  It is a situation  when the consumer gets maximum satisfaction with the given income and the given market prices. Indifference curve approch of consumers equillibrium: According to the indifference curve analysis, consumer's equilibrium is at a point where the slope of indifference curve is equal to the slope of budget line or price line.
Two conditions of the consumer's equilibrium are :

1. Indifference curve must be tangent to the budget line which means that the slope of indifference curve Should be equal to the slope of budget line.      Marginal Rate of Substitution of X on Y= ratio of the prices of the two goods i. e. {tex}\left( M R S _ { x y } \right) = \frac { \text { Price of } X \left( P _ { x } \right) } { \text { Price of } Y \left( P _ { y } \right) }{/tex}
2. At the point of MRS =Px/Py, indifference curve must be convex to the origin. It implies that at the point of equilibrium, MRS must be diminishing i.e. the rate at which one good is sacrificed for another should be falling. 

In the diagram given, P is the equilibrium point at which budget line touches the higher Indifference Curve IC₂, within the consumer budget.

• Point A could not be the point of equilibrium because at point A, MRS > P_x / P_y. Hence consumer will prefer to consume more of good X and less of good Y, as a result, Marginal utility of X (MU_X) will fall and Marginal utility of Y (MU_y) will rise, this process will continue till the time MRS =P_X/P_y.
• At point B MRS < Px/Py, hence consumer will demand more of good Y and less of good X. Because of this MU_X will rise and MUy will fall till the time MRS =P_X/P_y. So, the consumer will be at equilibrium only at point P. 

Differences between microeconomics and macroeconomics are given below

Normative economics deals with what ought to be based on value judgments. It is used to judge whether the economic events are desirable or not. 

Positive economics is objective and fact based, while normative economics is subjective and value based.
Positive economic statements must be able to be tested and proved or disproved. Normative economic statements are opinion based, so they cannot be proved or disproved.

Economic problem arises because of scarcity of resources and unlimited human wants.

(i) Wants are unlimited:

(a) This is a basic fact of human life. Human wants are unlimited.

(b) They are not only unlimited but also grow and multiply very fast. 

(ii) Resources are limited:

(a) The resources to produce goods and services to satisfy human wants are available in limited quantities. Land, labour, capital and entrepreneurship are the basic scare resources.

(b) These resources are available in limited quantities in every economy, big or small, developed or underdeveloped, rich or poor. Some economies may have more of one or two resources but not all the resources. Moreover the resources have alternate uses.

(c) For example, Indian economy has relatively more labour but less capital and land. The U.S. economy has relatively more land but less labour. No economy in the world has all the resources in abundance. (iii) Resources have alternative uses:

(iii) Generally a resource has many alternative uses.

(b) A worker can be employed in a factory, in a school, in a government office, self employed and so on.

(c) Like this, nearly all resources have alternative uses. But the problem is that which resource should be put to which use.

So, the economy has to decide as to how to utilise theser resources and which will be the best alternative for utilising the resources so that wants are satisfied to the maximum and the economy moves towards solving their central problems.

{tex}Median = l_1+ \frac{(\frac {n}{2} - c.f.)}{f} \times i{/tex}
where
{tex}l_1 {/tex} = lower limit of the median class
c.f. = cumulative frequency of the class preceding the median class
f = simple frequency of the median class
i = class interval of the median group or class.

You can check NCERT Solutions here : https://mycbseguide.com/ncert-solutions.html

Fuller utilisation of resources refers to a situation where the resources are used in a best possible manner. Generally any point on the production possibility curve will be fuller utilisation of resources. So, points on PPF the economy operates means resources are fully and efficiently used.