Select the correct observation about dilute solution of acetic acid. 1

(a) A student cannot see clearly a chart hanging on a wall placed at a distance of 3 from his eyes. Name the defect of vision he is suffering from. Draw a ray diagram to illustrate this effect . List its two possible causes.

(b) Draw a ray diagram to show how this defect maybe corrected using a lens appropriate focal length.

(c) An eye donation camp is being organized by social workers in your locality. and why would you help in this cause?

Explain the trends in the Modern Periodic Table of various properties like valency, atomic size, metallic and non-mettalic properties of the atoms of elements.

In the preparation of soap, a small amount of sodium chloride(common salt) is added to the mixture of fat and sodium hydroxide. The role of common salt is to

A student takes about 6 ml distilled water in four test tubes marked P, Q R and S. He dissolves sodium sulphate in P, potassium sulphate in Q, calcium sulphate in R and magnesium sulphate in S. After that he adds equal amount of soap solution in each test tube. On shaking these test tubes, he would observe a good amount of lather in the test tubes marked