MODEL PAPER 6 Science - MODEL PAPER 6

Assertion (A): Decomposers help in recycling of nutrients between living and non-living components of ecosystem.
Reason (R): Decomposers help in decomposing dead bodies of organisms and return various nutrient elements to their source viz soil, water and air.

Assertion (A): A compass needle is placed near a current-carrying wire. The deflection of the compass needle decreases when the compass needle is displaced away from the wire.
Reason (R): Strength of a magnetic field decreases as one moves away from a current-carrying conductor.

Assertion (A): During fertilization, the only head of the spermatozoa enters the egg.
Reason (R): If several spermatozoa hit the egg at the same time, all can enter the egg.

Assertion (A): Colour of copper sulphate solution changes when an iron nail is kept immersed in it.
Reason (R): The colour of copper sulphate solution changes when iron nail is kept immersed in it due to the decomposition reaction taking place between iron and copper leading to formation of iron sulphate.

Ozone depletion has resulted in:

Assertion (A): Colour of copper sulphate solution changes when an iron nail is kept immersed in it.
Reason (R): The colour of copper sulphate solution changes when iron nail is kept immersed in it due to the decomposition reaction taking place between iron and copper leading to formation of iron sulphate.

Assertion (A): During fertilization, the only head of the spermatozoa enters the egg.
Reason (R): If several spermatozoa hit the egg at the same time, all can enter the egg.

Assertion (A): A compass needle is placed near a current-carrying wire. The deflection of the compass needle decreases when the compass needle is displaced away from the wire.
Reason (R): Strength of a magnetic field decreases as one moves away from a current-carrying conductor.

Assertion (A): Decomposers help in recycling of nutrients between living and non-living components of ecosystem.
Reason (R): Decomposers help in decomposing dead bodies of organisms and return various nutrient elements to their source viz soil, water and air.

What happens to a beam of white light when it gets refracted through glass prism? Which colour deviates the most and the least after refraction through a prism? What is likely to happen if a second identical prism is placed in an inverted position with respect to the first prism. Justify your answer.

Mention the form of energy transfer, if a grasshopper is eaten by a frog.

What is the role of decomposers in the ecosystem?

State the function of Bowman's capsule and glomerulus.

a. What is the meaning of electric power of an electrical device? Write its SI unit.
b. An electric kettle of 2 kW is used for 2h. Calculate the energy consumed in (i) kilowatt hour and (ii) joules.

i. Name the spherical mirror used as:
a. shaving mirror
b. Rear view mirror in vehicles
c. Reflection in search-light.
ii. Write any three difference between a real and a virtual image.

Give the respective scientific terms used for studying
 i. The mechanism by which variations are created and inherited.
ii. the development of new types of organisms from the existing ones.

Describe internal structure of a human heart.

Draw a ray diagram in each of the following cases to show the formation of image, when the object is placed:
i. between optical center and principal focus of a convex lens.
ii. anywhere in front of a concave lens.
iii. at 2F of a convex lens.
State the signs and values of magnifications in the above mentioned cases (i) and (ii).

Form the image in case an object is moved from infinity to the concave mirror.

Following are the two examples of plant movement. One is drooping of leaves in touch-me-not plant and second is
attaching of pea plant to a support with the help of tendrils.
i. What is the stimulus which is common for movement in both the cases?
ii. What is the difference in movement in both the plants? Explain
iii. Give appropriate scientific terms for the movements described in both cases.

a. What is reproduction? List its two types.
b. How are the modes of reproduction different in unicellular and multicellular organisms?

An insulated copper wire wound on a cylindrical cardboard tube such that its length is greater than its diameter is called a solenoid. When an electric current is passed through the solenoid, it produces a magnetic field around it. The magnetic field produced by a current-carrying solenoid is similar to the magnetic field produced by a bar magnet. The field lines inside the solenoid are in the form of parallel straight lines. The strong magnetic field produced inside a current-carrying solenoid can be used to magnetize a piece of a magnetic material like soft iron when placed inside the solenoid. The strength of the magnetic field produced by a current-carrying solenoid is directly proportional to the number of turns and strength of the current in the solenoid.


(a) What would be the strength of the magnetic field inside a long current-carrying straight solenoid?
(b) Which end is north and which end is south pole when current flows through a solenoid?
(c) A long solenoid carrying a current produces a magnetic field B along its axis. If the current is double and the number of turns per cm is halved, then what will be the new value of the magnetic field?

OR

A soft iron bar is enclosed by a coil of insulated copper wire as shown in the figure. When the plug of the
key is closed, then where would the face B of the iron bar be marked?

Fill a conical flask with water. Cover the neck of the flask with a wire mesh. keep two or three freshly germinated bean seeds on the wire mesh. Take a cardboard box which is open from one side. Keep the flask a wire mesh. Kin the box in such a manner that the open side of the box faces light coming from a window as shown in the given figure. After two or three days, you will notice that the shoots bend towards light and roots away from light. Now turn the flask so that the shoots are away from light and the roots towards the light. Leave it undisturbed in this condition for a few days. Plants show tropism in response to other stimuli as well. The roots of a plant always grow downwards while the shoots usually grow upwards and away from the earth. This
upward and downward growth of shoots and roots, respectively, in response to the pull of earth or gravity, is obviously, geotropism.



(a) What has represented by the given activities?
(b) Do old parts of the shoot and root change direction? Is there any difference in the direction of the new growth?
(c) What can we conclude from this activity?

OR

What is geotropism?

Salt of a strong acid and strong base is neutral with a pH value of 7. NaCl common salt is formed by a combination of hydrochloride and sodium hydroxide solution. This is the salt that is used in food. Some salt is called rock salt, bed of rock salt was formed when seas of bygone ages dried up. The common salt thus obtained is an important raw material for various materials of daily use, such as sodium hydroxide, baking soda, washing soda, and bleaching powder.
(a). If given acids are phosphoric acid, carbonic acid, hydrochloric acid and sulphuric acid, then which acid
does not form an acidic salt?
(b). What is the formula of baking soda?

OR

Name the substance which on treatment with chlorine to obtain bleaching powder.