Board Paper of Class 10 2009 Science (SET 3) - Solutions

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

(1) I

(2) II

(3) III

(4) IV

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

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

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.

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)

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

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

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.

The labelling has been done correctly by student:

(1) A

(2) B

(3) C

(4) D

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.

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.

The correct recording of observations is that of the student:

(1) (A)

(2) (B)

(3) (C)

(4) (D)

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.

In the experiment to show that CO₂ is given out during respiration, the student uses:

(1) Lime water

(2) Alcohol

(3) KOH solution

(4) Iodine solution

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)

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

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

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

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

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

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

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