In the following food chain, 100 J of energy is available to the lion. How much energy was available to the producer? |
Plant \[\to \] Dear \[\to \] Lion |
(a) Water is an elixir of life, a very important natural resource. Your science teacher wants you to prepare a plan for a formative assessment activity. "How to save water, the vital natural resource". Write any two ways that you will suggest to bring awareness in your neighbourhood, on how to save water. |
(b) Name and explain any one way by which the underground water table does not go down further. |
(a) Write the functions of each of the following parts in a human female reproductive system |
(i) Ovary (ii) Uterus (iii) Fallopian tube |
(b) Write the structure and functions of placenta in a human female. |
Analyse the following observation table showing variation of image-distance (v) with object distance (u) in case of a convex lens and answer the questions that follow without doing any calculations: | ||
S. No. | Object - Distance u (cm) | Image - Distance v (cm) |
1. | \[\text{ }100\] | \[+\text{ }25\] |
2. | \[\text{ }60\] | \[+\text{ }30\] |
3. | \[\text{ }40\] | \[+\text{ }40\] |
4. | \[\text{ }30\] | \[+\text{ }60\] |
5. | \[\text{ }25\] | \[+\text{ }100\] |
6. | \[\text{ }15\] | \[+\text{ }120\] |
(a) What is the focal length of the convex lens? Give reason to justify your answer. | ||
(b) Write the serial number of the observation which is not correct. On what basis have you arrived at this conclusion? | ||
(c) Select an appropriate scale and draw a ray diagram for the observation at S. No. 2. Also find the approximate value of magnification. |
(a) If the image formed by a mirror for all positions of the object placed in front of it is always diminished, erect and virtual, state the type of the mirror and also draw a ray diagram to justify your answer. Write one use such mirrors are put to and why. |
(b) Define the radius of curvature of spherical mirrors. Find the nature and focal length of a spherical mirror whose radius of curvature is +24 cm. |
(a) A student suffering from myopia is not able to see distinctly the objects placed beyond 5 m. List two possible reasons due to which this defect of vision may have arisen. With the help of ray diagrams, explain |
(i) Why the student is unable to see distinctly the objects placed beyond 5 m from his eyes. |
(ii) The type of the corrective lens used to restore proper vision and how this defect is corrected by the use of this lens. |
(b) If, in this case, the numerical value of the focal length of the corrective lens is 5 m, find the power of the lens as per the new Cartesian sign convention. |
When you add a few drops of acetic acid to a test-tube containing sodium bicarbonate powder, which one of the following is your observation? |
(a) No reaction takes place. |
(b) A colourless gas with pungent smell is released with brisk effervescence. |
(c) A brown coloured gas is released with brisk effervescence. |
(d) Formation of bubbles of a colourless and odourless gas. |
While studying the saponification reaction, what do you observe when you mix an equal amount of colourless vegetable oil and 20% aqueous solution of NaOH in a beaker? |
(a) The colour of the mixture has become dark brown |
(b) A brisk effervescence is taking place in the beaker |
(c) The outer surface of the beaker has become hot |
(d) The outer surface of the beaker has become cold. |
A student requires hard water for an experiment in his laboratory which is not available in the neighbouring area. In the laboratory there are some salts, which when dissolved in distilled water can convert it into hard water. Select from the following groups of salts a group, each salt of which when dissolved in distilled water will make it hard. |
(a) Sodium chloride, Potassium chloride |
(b) Sodium sulphate, Potassium sulphate |
(c) Sodium sulphate, Calcium sulphate |
(d) Calcium sulphate, Calcium chloride |
To perform an experiment to identify the different parts of an embryo of a dicot seed, first of all you require a dicot seed. Select dicot seeds from the following group. |
Wheat, Gram, Maize, Pea, Barley, Ground-nut |
(a) Wheat, Gram and Pea |
(b) Gram, Pea and Ground-nut |
(c) Maize, Pea and Barley |
(d) Gram, Maize and Ground-nut |
The following vegetables are kept in a basket: |
Potato, Tomato, Radish, Brinjal, Carrot, Bottle-gourd |
Which two of these vegetables correctly represent the homologous structures? |
(a) Carrot and Tomato |
(b) Potato and Brinjal |
(c) Radish and Carrot |
(d) Radish and Bottle-gourd |
Study the given ray diagram and select the correct statement from the following: |
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(a) Device X is a concave mirror and device Y is a convex lens, whose focal lengths are 20 cm and 25 cm respectively. |
(b) Device X is a convex lens and device Y is a concave mirror, whose focal lengths are 10 cm and 25 cm respectively. |
(c) Device X is a concave lens and device Y is a convex mirror, whose focal length are 20 cm and 25 cm respectively. |
(d) Device X is a convex lens and device Y is a concave mirror, whose focal length are 20 cm and 25 cm respectively. |
A student obtains a blurred image of a distant object on a screen using a convex lens. To obtain a distinct image on the screen he should move the lens |
(a) away from the screen |
(b) towards the screen |
(c) to a position very far away from the screen. |
(d) either towards or away from the screen depending upon the position of the object. |
A student very cautiously traces the path of a ray through a glass slab for different values of the angle of incidence \[(\angle i)\]. He then measures the corresponding values of the angle of refraction \[(\angle r)\] and the angle of emergence \[(\angle e)\] for every value of the angle of incidence. On analysing these measurements of angles, his conclusion would be: |
(a) \[\angle i>\angle r>\angle e\] |
(b) \[\angle i=\angle e>\angle r\] |
(c) \[\angle i<\angle r<\angle e\] |
(d) \[\angle i=\angle e<\angle r\] |
Study the following ray diagram |
![]() |
In this diagram, the angle of incidence, the angle of emergence and the angle of deviation respectively have been represented by |
(a) y, p, z |
(b) x, q, z |
(c) p, y, z |
(d) p, z, y |
A student focuses the image of a candle flame, placed at about 2 m from a convex lens of focal length 10 cm, on a screen. After that he moves gradually the flame towards the lens and each time focuses it?s image on the screen. |
(a) In which direction does he move the lens to focus the flame on the screen? |
(b) What happens to the size of the image of the flame formed on the screen? |
(c) What difference is seen in the intensity (brightness) of the image of the flame on the screen? |
(d) What is seen on the screen when the flame is very close (at about 5 cm) to the lens? |
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