5. How does the speed of sound change on increasing the temperature? 1 6.What do you mean by photoperiod? Name two processes that are dependent on photoperiod. 2 7. What will happen if:
i) The skin epithelium is not stratified.
ii) Stratified squamous epithelium lines blood vessels. 2 8. Name the target organ/organ system of AIDS virus. What is the cause of death in case of people suffering from AIDS? 2 9. What is meant by (i) a solute and (ii) a solvent in a solution? Identify the solute and the solvent in a homogenous mixture of iodine and alcohol. 2 10. A housewife churned full cream milk with a milk churner. (i) What did she observe after churning milk?
(ii) What could be the possible reason for this observation? 2
11. The average atomic mass of a sample of an element ‘X’ is 16.2µ. What is the percentage of each isotope 16X and 18X in the sample? 2 12.Why does a wooden block float and an iron block sinks when both are placed on the surface of water ?2
13. The gravitational force of attraction between two masses is 16 N. What would be the force of attraction between them if each mass and the distance between them are doubled? 2 14. A child winds his toy car by moving its key. Name the type of energy – i) used up in the process
ii) energy transformation taking place in it
The car then runs on the floor of the room. Give the transformation of energy taking place in it now. 2
15. To increase productivity per unit area ,the farmers grow two different types of crops on the same field in definite rows. What is this practice called? What care is required to be taken before selecting two crops for such practice and why? Give any two reasons 3.
16. Draw a neat diagram of the leaf epidermis showing pores through which exchange of gases takes place. Label any two parts giving one function of each. 3 17. i) Which of the following diseases are protozoan in origin? a)Dengue b)Malaria c)Kalaazar d)AIDS ii) Suggest any two ways you would like to adopt, to prevent being infected by them. 3 18. Write two properties each of a solution, suspension and a colloid with respect to stability and filterability. 3
19. (i) State ‘Law of constant proportions’.
(ii) Taking the example of water, explain the law of constant proportions. (iii) Which postulate of Daltons’ atomic theory explains this law? 3
20. (i) Write the names of the compounds represented by the following formulae: a) Na 2Sb) KNO 3
(ii) Write the chemical formulae of :
(iii) Find out the mass of 12.044 × 10 23 atoms of magnesium (Given at mass of Mg = 24.0µ) 3
21. A stone is dropped from the edge of the roof.
a) How long does it take to fall 4.9 m?
b) How fast does...