Q. How are we able to see distant and nearby objects clearly? Which part of eye helps in changing curvature of lens? Why no image is formed at blind spot?
Q. (a) Which property of carbon leads to formation of large number of compounds? Define it.
(b) What is the functional group in the following molecules?
(i) CH3CH2CH2OH
(ii) CH3COOH
Q. (a) Why magnification is taken negative for real images and positive for virtual images?
(b) Why convex mirror is used in rear view mirrors and not concave mirror?
Q. (a) What are ‘magnetic field lines’? How is the direction of a magnetic field at a point determined ?
(b) Draw two field lines around a bar magnet along its length on its two sides and mark the field directions on them by arrow marks.
Q. (a) Mention the pH range within which our body works. Explain how antacids
give relief from acidity. Write the name of one such antacid.
(b) Fresh milk has a pH of 6. How does the pH will change as it turns to curd? Explain your answer.
(c) A milkman adds a very small amount of baking soda to fresh milk. Why does this milk take a longer time to set as curd?
(d) Mention the nature of toothpastes. How do they prevent tooth decay?
Q. . (a) Define tidal energy.
(b) Explain how the tidal energy is harnessed and write one limitation of the use of tidal energy.
Q. In the experiment “Light is essential for photosynthesis”, why does the uncovered part of the leaf turn blue-black after putting iodine solution?
Q. Name the two sets of nerves that constitute the peripheral nervous system.
Q. What are the modes of excretion in plants?
Q. Mention the essential material (chemicals) to prepare soap in the laboratory. Describe in brief the test of determining the nature (acidic/alkaline) of the reaction mixture of saponificationreaction.
Answers
1)we can see nearby objects as well as far away objects clearly by the action of cilary muscles on the eye lens. when cilary muscles relax the lens becomes thin focal length increases ans we can see distant objects clearly. and vica - versa
no image is formed on the blind spot because there are no light sensitive cells present near the blind spot.
2)catenation. it is the self linking property of carbon to form long, straight, branched chains of different sizes.
b)1) aldehyde
2)carboxylic acid
a) the focal length, is positive for a concave mirror, and negative for a convex mirror. ... When the image distance is negative, the image is behind the mirror, so the image is virtual and upright. A negative m means that the image is inverted. Positive means an upright image
b) because they give wider field of view and image is always erect.
Answer:
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