| How many groups and periods are there in the modern periodic table? How do the atomic size and metallic character of elements vary as we move: |
| (a) down a group and |
| (b) from left to right in a period |
| From the following elements: |
| \[_{4}Be;{{\,}_{9}}F;{{\,}_{19}}K;{{\,}_{20}}Ca\] |
| (i) Select the element having one electron in the outermost shell. |
| (ii) two elements of the same group. |
| Write the formula of and mention the nature of the compound formed by the union of \[_{\mathbf{19}}\mathbf{K}\] and element X(2, 8, 7). |
| (i) ?Planaria, insects, octopus and vertebrates all have eyes. Can we group eyes of these animals together to establish a common evolutionary origin? Justify your answer. |
| (ii) ?Birds have evolved from reptiles?. State evidence to prove the statement. |
| After the examinations Rakesh with his friends went on a picnic to a nearby park. All friends carried cooked food packed in plastic bags or plastic cans. After eating the food some friends collected the leftover food and plastic bags etc. planned to dispose them off by burning. Rakesh immediately checked them and suggested to segregate the leftover food and peels of fruits from the plastic materials and respectively dispose them off separately in the green and red dustbins placed in the corner of the park. |
| (a) In your opinion, is burning plastic an eco-friendly method of waste disposal? Why? State the advantage of method suggested by Rakesh. |
| (b) How can we contribute in maintaining the parks and roads neat and clean? |
| 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. |
| How many pairs of chromosomes are present in human beings? Out of these how many are sex chromosomes? How many types of sex chromosomes are found in human beings? |
| 'The sex of a newborn child is a matter of chance and none of the parents may be considered reponsible for it.' Draw a flow chart showing determination of sex of a newborn to justify this statement. |
| (a) State the laws of refraction of light. Explain the term absolute refractive index of a medium and write an expression to relate it with the speed of light in vacuum. |
| (b) The absolute refractive indices of two media 'A' and 'B' are 2.0 and 1.5 respectively. If the speed of light in medium 'B' is \[2\times {{10}^{8}}\,m/s,\] calculate the speed of light in: |
| (i) vacuum, |
| (ii) medium 'A' |
| 'A convex lens can form a magnified erect as well as magnified inverted image of an object placed in front of it.' Draw ray diagram to justify this statement stating the position of the object with respect to the lens in each case. |
| An object of height 4 cm is placed at a distance of 20 cm from a concave lens of focal length 10 cm. Use lens formula to determine the position of the image formed. |
| A student is unable to see clearly the words written on the blackboard placed at a distance of approximately 4 m from him. Name the defect of vision the boy is suffering from. Explain the method of correcting this defect. Draw ray diagram for the: |
| (i) defect of vision and also |
| (ii) for its correction. |
| A student adds 2 mL of acetic acid to a test tube containing 2 mL of distilled water. He then shakes the test tube well and leaves it to settle for some time. After about 5 minutes he observes that in the test tube there is: |
| (a) a clear transparent colourless solution |
| (b) a clear transparent pink solution |
| (c) a precipitate settling at the bottom of the test tube |
| (d) a layer of water over the layer of acetic acid |
| A student prepared 20% sodium hydroxide solution in a beaker to study saponification reaction. Some observations related to this are given below: |
| (I) Sodium hydroxide solution turns red litmus blue |
| (II) Sodium hydroxide readily dissolves in water |
| (III) The beaker containing solution appears cold when touched from outside. |
| (IV) The blue litmus paper turns red when dipped into the solution |
| The correct observations are: |
| (a) I, II and IV (b) I, II, and III |
| (c) only III and IV (d) only I and II |
| Hard water is not available for an experiment. Some salts are given below: |
| (I) Sodium chloride |
| (II) Sodium sulphate |
| (III) Calcium chloride |
| (IV) Calcium sulphate |
| (V) Potassium chloride |
| (VI)Magnesium sulphate |
| Select from the following a group of these salts each member of which may be dissolved in water to make it hard. |
| (a) I, II, V (b) I, III, V |
| (c) III, IV, VI (d) II, IV, VI |
| A student identified the various parts of an embryo of a gram seed and listed them as given below: |
| (I) Testa |
| (II) Plumule |
| (III) Radicle |
| (IV) Cotyledon |
| (V) Tegman |
| Out of these the actual parts of the embryo are: |
| (a) I, II, III (b) II, III, IV |
| (c) III, IV, V (d) II, IV, V |
| Four students A, B, C and D reported the following set of organs to be homologous. Who is correct? |
| (a) Wings of a bat and a butterfly. |
| (b) Wings of a pigeon and a bat. |
| (c) Wings of a pigeon and a butterfly. |
| (d) Forelimbs of cow, a duck and a lizard. |
| Study the following diagram and select the correct statement about the device ?X?: |
 |
| (a) Device 'X' is a concave mirror of radius of curvature 12 cm. |
| (b) Device 'X' is a concave mirror of focal length 6 cm. |
| (c) Device 'X' is a concave mirror of focal length 12 cm. |
| (d) Device 'X' is a convex mirror of focal length 12 cm. |
| A student has obtained a point image of a distant object using the given convex lens. To find the focal length of the lens he should measure the distance between the: |
| (a) lens and the object only |
| (b) lens and the screen only |
| (c) object and the image only |
| (d) lens and the object and also between the object and the image |
| Four students P, Q, R and S traced the path of a ray of light passing through a glass slab for an angle of incidence \[\mathbf{4}{{\mathbf{0}}^{\mathbf{o}}}\] and measured the angle of refraction. The values as measured them were \[\mathbf{1}{{\mathbf{8}}^{\mathbf{o}}}\mathbf{;}\,\mathbf{2}{{\mathbf{2}}^{\mathbf{o}}}\mathbf{;}\,\mathbf{2}{{\mathbf{5}}^{\mathbf{o}}}\] and \[\mathbf{3}{{\mathbf{0}}^{\mathbf{o}}}\] respectively. The student who has performed the experiment methodically is |
| (a) P (b) Q |
| (c) R (d) S |
| After tracing the path of a ray of light through a glass prism a student marked the angle of incidence \[(\angle i),\] angle of refraction \[(\angle r),\] angle of emergence \[(\angle e)\] and the angle of deviation \[(\angle D)\] as shown in the diagram. The correctly marked angles are: |
 |
| (a) \[\angle i\] and \[\angle r\] |
| (b) \[\angle i\] and \[\angle e\] |
| (c) \[\angle i,\,\angle e\] and \[\angle D\] |
| (d) \[\angle i,\,\angle r\] and \[\angle e\] |
| To find the image-distance for varying object-distances in case of a convex lens, a student obtains on a screen a sharp image of a bright object placed very far from the lens. After that he gradually moves the object towards the lens and each time focuses its image on the screen. |
| (a) In which direction - towards or away from the lens, does he move the screen to focus the object? |
| (b) What happens to the size of image-does it increase or decrease? |
| (c) What happen when he moves the object very close to the lens? |
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