'A very small sample of tissue or even a drop of blood can help determine paternity.'' Provide a scientific explanation to substantiate how it is possible.

The main application of osmotic pressure measurement is in the determination of the molar mass of a substance which is either slightly soluble or has a very high molar mass such as proteins, polymers of various types and colloids.This is due to the fact that even a very small concentraion of the solution produces fairly large magnitude of osomotic pressure.In the laboratory the concentrations usually employed are of the order of 10^(-3) to 10^(-4) M.At concentration of 10^(-3) mol dm^(-3) , the magnitude of osmotic pressure of 300 K is : P=10^(-3)xx0.082xx300=0.0246 atm or 0.0246xx1.01325xx10^5=2492.595 Pa At this concentration, the values of other colligative properties such as boiling point elevation and depression in freezing point are too small to be determined experimentally. Further polymers have following two types of molar masses : (A) Number average molar mass (barM_n) , which is given by (undersetisumN_iM_i)/(undersetisumN_i) where N_i is the number of molecules having molar mass M_i . (B) Molar average molar mass (barM_m) , which is given by (undersetisumN_iM_i^2)/(undersetisumN_iM_i) Obviously the former is independent of the individual characteristics of the molecules and gives equal weightage to large and small molecules in the polymer sample.On the other hand later gives more weightage to the heavier molecules.Infact with the help of a colligative property only one type of molar mass of the polymer can be determined. One gram each of polymer A (molar mass=2000) and B(molar mass=6000) is dissolved in water to form one litre solution at 27^@C .The osmotic pressure of this solution will be :

Read the following statements about respiratory system of humans : I. Type II alveoli help in secretion of a chemical surfactant called lecithin , which decreases the surface tension around alveoli. II. The diffusion membrane for exchange of gases is made up of three major cellular layers. III. Binding of oxygen with hemoglobin is primarily related to the partial pressure of O_2 . IV. Every 100 ml of oxygenated blood can deliver around 5 ml CO_2 to the tissues under normal physiological conditions. How many statement is /are correct from the above ?

It is very commonly thought that the sciences and humanities are producing two cultures which are opposed to each other. Science is even accused of not being sympathetic to the well-being of society. All this is due to the debatable use made by some scientists of their discoveries. However, science has now become increasingly aware of its responsibility towards society. Consequently, many scientists are of the opinion that science should be defined in humanistic terms. According, I.I. Rabi defines science as follows : "Science is an adventure of the whole human race to learn to live in and perhaps to love the universe in which they are. To be a part of it is to understand it, to understand oneself, to begin to feel that there is a capacity within man far beyond that he felt he had, of an infinite extension of human possibilities - not just on the material side..." Rabi proposes that science be taught “with a certain historical understanding, with a certain philosophical understanding, with a social understanding and a human understanding". At the moment, we are dealing with physics and one might well ask if we can define physics also in humanistic terms. Gerald Halton provides us with a relevant definition of physics. According to him : "Physics is a sequence of related ideas whose pursuit provides one with the cumulative effect of an even higher vantage point and a more encompassing view of the working of nature. Physics is neither an isolated bloodless body of facts and theories with mere vocational usefulness, nor a glorious entertainment restricted to an elite of specalists. Rather students of physics may leave them unprepared for their own time. They can be neither participants nor even intelligent spectators in one of the great adventures”. It will be no exaggeration if we say that the fate of society is linked to physics as whatever is thought or discovered in physics immediately affects the society. Our intellegence lies in applying physics to solve the pressing problems that the society faces and not to annihilate it. According to I.I Rabi