10 Science Solved Sample Paper 5 – Page 4
Question: 22. The pH value of water below 25° C is greater than 7. Does water have basic nature? Give reason for your answer. 
Answer: Yes, then such water will be basic in nature. As bases have pH value greater than 7. Such cold water has more (OH)¯ ions, and thus such water will turn red litmus to blue.
Riya performs two set of experiments to study the length of the foam formed which are as follows:
Set I: She takes 10 ml of distilled water in test tube “A” and adds 5-6 drops of liquid soap in it and shakes the test tube vigorously.
Set II: She takes 10 ml of distilled water in test tube “A” and adds 5-6 drops of liquid soap with half spoonful of CaSO4 in it and shakes the test tube. Write your observation and reason.
Question: 23. Two equivalent resistors are connected in series. Draw the circuit diagram for determining the resultant resistance. Give the formula to determine the result resistance. 
Question: 24. Why is epidermal peel generally taken from lower surface of the leaf? Name the cells which surround the stomata. 
Hint: As lower surface of the has stomata pores in the lower epidermis of the leaf.
Gaurd cells suround the stoma (stomata).
Question: 25. How will you test gas evolved in the reaction of acetic acid with sodium bicarbonate? Give two tests and reason for your observation. 
- Pass the gas through lime water, if it turns milky due to formation of CaCO3(s), it is Co2.
- Bring a burning matchstick near the gas; if it gets extinguished, it shows gas is CO2 as it does not support combustion.
Question: 26. In the experiment “To study fission in amoeba and budding in yeast”, mention the difference between the two reproduction methods based on parental identity only. 
Answer: In binary fission, the parental identity is lost; In budding, the parental cell continues to live.
A student observed a permanent slide showing asexual reproduction in yeast. Draw diagrams of the observations he must have made from the slide. Name the process also.
Question: 27. Ria obtained a sharp image of the grill of a window on a screen, using a convex lens. For getting better results the teacher suggested focusing of a distant tree instead of grill. In which direction should the lens be removed for this purpose? Give reason in support of your answer.
Answer: As distant tree is at a much greater distance than the grill of a window of room, the image will be formed at a lesser distance. Hence, should be moved towards the screen.