Science Pre Board 1

Why is Government of India imposing a ban on the use of polythene bags? Suggest two alternatives to these bags and explain how this ban is likely to improve the environment.

What are artificial magnets? What are their common shapes?

A cross was made between pure breeding pea plants one with round and green seeds and the other with wrinkled and yellow seeds.

(a) Write the phenotype of F1 progeny. Give reason for your answer.

(b) Write the different types of F2 progeny obtained along with their ration when F1 progeny was selfed.

Given below are some elements of the modern periodic table:             ₄Be, ₉Fe, ₁₄Si, ₁₉K, ₂₀Ca

(i) Select the element that has one electron in the outermost shell and write its electronic configuration.

(ii) Select two elements that belong to the same group. Give reason for your answer.

(iii) Select two elements that belong to the same period. Which one of the two has bigger atomic size?

Write the functions of the following in human female reproductive system:  Ovary, oviduct, uterus. How does the embryo get nourishment inside the mother's body? Explain in brief.

Explain Mendel’s law of independent inheritance. Give one example.

Define evolution. How does it occur? Describe how fossils provide us evidences in support of evolution.

List four points of significance of reproductive health in a society. Name any two areas related to the reproductive health which have improved over the past 50 years in our country.

Draw the pattern of magnetic field lines around a straight conductor carrying electric current. Apply right hand thumb rule to mark the direction of magnetic field.

(a) Define the term 'isomers'.        

(b) Draw two possible isomers of the compound with molecular formula C₃H₆O and write their names.

(c) Give the electron dot structures of the above two compounds.

(a) A person cannot read newspaper placed nearer than 50 cm from his eyes. Name the defect of vision he is suffering from. Draw a ray diagram to illustrate this defect. List its two possible causes. Draw a ray diagram to show how this defect may be corrected using a lens of appropriate focal length.    

(b) We see advertisements for eye donation on television or in newspapers. Write the importance of such advertisements.

A gas is liberated immediately with a brisk effervescence when you add acetic acid to sodium hydrogen carbonate powder in a test tube. Name the gas and describe the test that confirms the identity of the gas.

Dry raisins were soaked in water for 2 hours, to determine the percentage of water absorbed by raisins. Before final weighing of swollen raisins, the extra water left on the surface of soaked raisins was removed by:

In the figure, the parts marked A, B and C is sequentially: 

Iron nails were dipped in an aqueous solution of copper sulphate. after about 30 mintues, it was observed that the colour of the solution changed from

A student has obtained a magnified image of a flame on a screen using a convex lens. To draw the corresponding ray diagram to show the image formation, which of the following two rays whose paths after refraction are shown, should he select?