# 10th Science Paper Solutions Set 3 (Practical) : CBSE Delhi Previous Year 2009

General Instructions:
1. Attempt all questions.
2. There are 30 multiple choice questions in total. Only one of the options in every question is correct.
3. The question paper consists of two sections - Section A and Section B. Each of the 20 questions in Section A carries half mark and each of the 10 questions in Section B carries one mark.
4. 15 minutes additional time will be given to you to read the questions.
Q1 :

The ‘set up’, used in the laboratory, to collect sulphur dioxide, is that shown in figure:

(1) I

(2) II

(3) III

(4) IV

SO2is heavier than air and as a result, is collected by the upward displacement of air in a jar.

Q2 :

A student determines the focal length of a device X, by focussing the image of a far off object on the screen positioned as shown in the figure below.

The device X is a:

(1) Convex lens

(2) Concave lens

(3) Convex mirror

(4) Concave mirror

It can be observed that the parallel rays of light falling on device Xreflect and converge at a point on the screen. Since concave mirrors tend to focus all the incoming parallel rays after reflection, device X is a concave mirror.

Q3 :

A student traces the path of a ray of light passing through a rectangular glass slab.

For measuring the angle of incidence, he must position the protractor in the manner shown in figure:

(1) A

(2) B

(3) C

(4) D

The protractor must be placed along the normal to the base so that its zero degree marking line (base) coincides with the normal, and its readings lie on the side of the incident ray, as shown below.

Q4 :

In an experiment on finding the equivalent resistance of two resistors, connected in series, a student connects the terminals of the voltmeter, to:

(1) one terminal of each of the two resistors and these terminals are not interconnected.

(2) one terminal of each of the two resistors and these terminals are also interconnected.

(3) both the terminals of each of the two resistors.

(4) both the terminals of one resistor and one terminal of the other resistor.

Q5 :

For plotting temperature-time graph for a hot body, as it cools to room temperature, a student is to choose one each from each of the following pairs.

A: Calorimeter

(i) blackened from outside

(ii) polished from outside

B: Base for keeping the calorimeter

(i) insulated

(ii) metallic

In order to get the correct graph he should prefer to choose:

(1) A (i), B (ii)

(2) A (ii), B (ii)

(3) A (i), B (i)

(4) A (ii), B (i)

Q6 :

A student sets up a slinky on a smooth table top in the manner shown here.

How can he produce transverse waves in the slinky by moving its free end Q?

(1) at an angle of 45°with the table top

(2) backward and forward along the length of the slinky

(3) up and down

(4) left and right

Q7 :

A student carefully observes the parts labelled A and B in the given diagram and classifies the plant correctly as:

(1) a bryophyte

(2) a pteridophyte

(3) a gymnosperm

(4) an angiosperm

Q8 :

Four students (A − D), independently observed parenchyma under the microscope and labelled the parts, marked I, II, III, IV, V, as per the record given below.

 Student I II III IV V A Cell membrane Nucleus Cell wall Vacuole Cytoplasm B Cytoplasm Cell membrane Vacuole Cell wall Nucleus C Vacuole Cell wall Nucleus Cell membrane Cytoplasm D Cell wall Inter cellular space Nucleus Cytoplasm Vacuole

The labelling has be

Q9 :

The correct procedure for preparing a colloidal solution of egg albumin in water is:

(1) to break the egg shell, take only the white portion and to add it to water with constant stirring.

(2) to break the egg shell, take only the yellow portion and to add it to boiling water with constant stirring.

(3) to boil the egg first, to break the egg shell, to add the white portion to ice cold water and to mix.

(4) to boil the egg first, to break the egg shell, to add the yellow portion to water and to mix.

Q10 :

Four students (A), (B), (C) and (D) independently observed the evaporation of water under different conditions, and recorded the temperature of water at regular intervals as shown below.

 Student Placing of experimental set up in/under Temperature recording for 15 minutes (A) sun increased gradually (B) open air decreased gradually (C) a fan initially increased, then became constant (D) a corner of the room initially increased, then gradually decreased

The correct recording of observations is that of the student:

(1) (A)

(2) (B)

(3) (C)

(4) (D)

Q11 :

A student takes a mixture of sand and ammonium chloride in china dish and heats it under a funnel fitted with a plug over a flame. He would observe that:

(1) solid sand gets deposited on the lower cooler parts of the funnel while solid ammonium chloride remains in the china dish.

(2) sand and ammonium chloride get deposited on hotter parts of the funnel.

(3) ammonium chloride gets deposited on the cooler parts of the funnel and sand remains in the china dish.

(4) sand collects on cooler parts of the funnel while ammonium chloride melts in the china dish.

Q12 :

In the experiment to show that CO2is given out during respiration, the student uses:

(1) Lime water

(2) Alcohol

(3) KOH solution

(4) Iodine solution

Q13 :

Raisins are soaked in water for determining the percentage of water absorbed by raisins. The formula, used by a student, for calculating the percentage of water absorbed, is:

(1)

(2)

(3)

(4)

Q14 :

The steps, necessary for setting up the experiment, “To demonstrate that light is necessary for photosynthesis” are not given here in proper sequence.

I. Keep the potted plant in sunlight for 3 to 4 hours.

II. Keep the potted plant in darkness for about 48 hours.

III. Cover a leaf of the plant with a strip of black paper.

IV. Pluck the leaf and test it for starch.

The correct sequence of steps is:

(1) I, III, IV, II

(2) I, IV, III, II

(3) II, IV, III, I

(4) II, III, I, IV

Q15 :

A specimen of a fish was given to students to identify the externally visible chordate feature in it. The students would look for:

(1) Operculum

(2) Notochord

(3) Dorsal tubular nerve cord

(4) Post anal tail

Q16 :

A student adds a few drops of the universal indicator to a solution of dilute hydrochloric acid in the way shown here. He would observe that the colour of the solution changes from colourless to:

(1) red

(2) yellow

(3) violet

(4) green

Q17 :

A student takes some zinc granules in a test tube and adds dilute hydrochloric acid to it. He would observe that the colour of the zinc granules changes to:

(1) white

(2) black

(3) brown

(4) yellow

Q18 :

A student takes some water in a beaker and heats it over a flame for determining its boiling point. He keeps on taking its temperature readings. He would observe that the temperature of water:

(1) keeps on increasing regularly

(2) keeps on increasing irregularly

(3) first increases slowly, then decreases rapidly and eventually becomes constant

(4) first increases gradually and then becomes constant

Q19 :

While performing an experiment on verifying the laws of reflection of sound, a student is to choose between (i) a narrow or a wide tube and (ii) a strong or a faint source of sound.

The observed experimental difference, between the values of angle of incidence and angle of reflection, is likely to be minimum when he chooses a:

(1) narrow tube and a faint source

(2) wide tube and a faint source

(3) narrow tube and a strong source

(4) wide tube and a strong source

Q20 :

The magnitude of zero error of the spring balance and least count of the measuring cylinder, shown here, are, respectively:

(1) 2.5 g and 0.1 mL

(2) 5.0 g and 0.1 mL

(3) 2.5 g and 0.2 mL

(4) 5.0 g and 0.2 mL

Q21 :

Four students observed the colour and odour of acetic acid and its reaction with sodium hydrogen carbonate. They tabulated their observations as given below.

 Student Colour of acetic acid Odour of acetic acid Action with sodium hydrogen carbonate A B C D blue colourless light green light brown fruity smell of vinegar odourless rotten egg gas evolves without bubbles effervescence gas evolves without bubbles effervescence

The correct set of observation is that of student:

(1) A

(2) B

(3) C

(4) D

Q22 :

Four students A, B, C and D while performing an experiment on establishing the relation between the loss of weight of a small solid when fully immersed in tap water, and the weight of water displaced by it, used for different shapes of overflow cans containing water as shown.

The arrangement, that would give correct results, is that of student:

(1) (A)

(2) (B)

(3) (C)

(4) (D)

Q23 :

Four stages of binary fission in amoeba are shown below. The stage at which nuclear fission and cytokineses are observed is, stage

(1) I

(2) II

(3) III

(4) IV

Q24 :

A student takes Cu, Al, Fe and Zn strips, separately in four test tubes labelled as I, II, III and IV respectively. He adds 10 mL of freshly prepared ferrous sulphate solution to each test tube and observes the colour of the metal residue in each case.

He would observe a black residue in the test tubes:

(1) (I) and (II)

(2) (I) and (III)

(3) (II) and (III)

(4) (II) and (IV)

Q25 :

Four students, (A), (B), (C) and (D) observed the colour and solubility of iron, sulphur and iron sulphide in carbon disulphide. The tick mark (||) represents ‘soluble’, and cross mark (&mnCross;) represents ‘insoluble’, in carbon disulphide. Their observations are tabulated below.

 Student Colour Solubility in carbon disulphide Fe S FeS Fe S FeS (A) Yellow Silvery Greyish silver (||) (&mnCross;) (||) (B) Silvery Orange Reddish brown (&mnCross;)

Q26 :

For three circuits, shown here

the same two resistors R1and R2have been connected in parallel in all the circuits but the voltmeter and the ammeter have been connected in three different positions. The relation between the three voltmeter and ammeter reading would be:

(1) V1 = V2= V3and I1= I2= I3

(2) V1V2V3and I1= I2= I3

(3) V1 = V2 = V3and I1I2I3

(4) V1V2V3and I1

Q27 :

While observing the occurrence of plasmolysis in onion peel cells, four students (W−Z) respectively placed the peels in four different liquids (A−D): (A): Water, (B): Sugar solution, (C): Alcohol and (D): Safranin

The correct choice of liquid is that of student:

(1) W

(2) X

(3) Y

(4) Z

Q28 :

Four students, A, B, C and D, make the records given below, for the parts marked X and Y in this diagram.

 Student X Y A B C D Stoma Guard cell Epidermal cell Stoma Guard cell Stoma Stoma Epidermal cell

The correct record, out of these, is that of student:

(1) A

(2) B

(3) C

(4) D

Q29 :

The following ‘precautions’ were listed by a student in the experiment on study of ‘Dependence of current on potential difference’.

(A) Use copper wires as thin as possible for making connections.

(B) All the connections should be kept tight.

(C) The positive and negative terminals of the voltmeter and the ammeter should be correctly connected.

(D) The ‘zero error’ in the ammeter and the voltmeter should be noted and taken into consideration while recording the measurements.

(E) The ‘key’ in the circuit, once plugged in, should not be taken out till all the observations have been completed.

The ‘precautions’ that need to be corrected and revised are:

(1) (A), (C) and (E)

(2) (C) and (E)

(3) (B) and (E)

(4) (A) and (E)

Q30 :

Which one of the following is the correct step, in the procedure for making a temporary slide of human cheek cells?

(1) Place the cheek cell scrapings in a watch glass containing water.

(2) Place cheek cell scrapings in the centre of a clean slide.

(3) Dip the toothpick, containing cheek cell scrapings, in the stain and then transfer to a clean slide.

(4) Obtain cheek cells, directly on the slide, using its edge to scrape the inside of the cheek.