Human Skeleton

Scientists around the world

Summer Vacations Holiday Homework

Class VIII

2011-12

Subject: Science

Physics ,Chemistry

1.    Learn and write all the questions already done in your notebook in a separate copy.

2.    Make a puzzle of 10-15 hints from the chapter ‘ Metals and Non-metals’.

3.    Make a working model on any one of the following topic-

a)    Types of friction

b)    Any 1 method of reducing friction

Biology

1.    Make a powerpoint presentation on any one topic-

a)    Project Tiger

b)    National Parks and wild life sanctuaries in India

2.    Make a project on the topic ‘ Food Preservation’.

3.    Revise following lessons for test-

a)    The Cell – Its structure and function

b)    Microorganisms- Friends or Foes

Class 7

SUBJECT- SCIENCE

HEAT

Revision assignment 1

Q1  State two impotant facts about Heat.

Q2  How do we express degree of hotness of a body?

Q3  Does a cold object possesses heat energy? Why? How is the temperature of an object related to the motion of its particles?

Q4  How many types of thermometers are there?

Q5  Explain the construction of an ordinary mercury thermometer.

Q6  Complete the answer of given question by filling up suitable words.

Ø  What are the physical effects of heat?

                                            i.            Change in _____ : Addition of heat ____ the temperature of object whereas removal of heat ______ it.

                                          ii.            Change of state: When heat is added to a solid, it changes into ______ and when heat is added into a _______, it changes into a _____.Similarly when heat is removed, ______ changes into _____ and ______ into ______.

                                        iii.            ___________: Most solids, ______ and _______ _______ on heating.

                  

Ø  What chemical effect does heat show?

                                            i.            Many ________ reactions occur on heating the _____. For example oxygen can be prepared on heating ________ with _______ as a catalyst over a flame.

Ø  What are the differences between clinical thermometer and laboratory thermometer?

There are two differences-

1.      The range of _____thermometer is from 35°C to _____ whereas the range of_______ thermometer is from -10°C to 110°C.

2.      _______ thermometer has a slight bend or ________ in its capillary tube whereas _______ thermometer does not have any such bend or _____.

       

Q7 A special instrument used to measure temperature is called __________.

Q8 The difference in the temperature of the two fixed reference points is called the _____ of the  

      thermometer.

Q9 The scales used to measure the temperature are ________ & ________.

Q10 A specially designed and calibrated thermometer to measure our body temperature is known

        as the _____________.

Q11 Why does a clinical thermometer has a constriction?

separation of substances

CLASS VI

                                                     SUBJECT- SCIENCE

                                                TOPIC- Separation of Substances

                                                      Revision assignment 1

Q1  Define 1) Mixtures  2) Pure substances

Q2  Can we use the method of crystallization to purify water?

Q3  Solve the following puzzle:

	1
2
									3
4
5

Across: 2 to separate husk from grains 4 method used at home to obtain butter 5 method to purify water fast

Down: 1 used to get tea by separating tea leaves 3 to get salt

      

Q5 What is the difference between homogenous and heterogenous mixtures?

Q6 Name the method

a.       In which dried stalks are beaten to separate the grains.

b.      In which mixture is allowed to fall fom a heigt and the lighter particles blow away with air and fall at a distance while heavier particles fall nearer.

c.       In which a wire mesh fixed tightly in a frame is used.

d.      In which a liquid with heavier insoluble solid impurity is left undisturbed and then removed in a separate container.

e.       In which mixture is rotated at a high speed.

Q7 In which situations ( properties of mixtures) are the following methods used?

a.       Hand picking

b.      Sublimation

c.       Filteration

d.      Loading

e.       Separating funnel

Q8 Complete the answer by filling up suitable words.

Ø  What is the difference between evaporation and crystallization?

Evaporation is the method used to separate ___ solid substances from a ____.In this liquid changes into___ form on ______.It is commonly used to obtain _____ from sea water. _____ water is collected in shallow ______ and due to the ________ water gets evaporated and ___ is left behind.                  

Crystallization is used to obtain ____ solids from a solution. It is a process in which               mixture is heated to separate a pure solid in the form of its _____ from a ____solution. It is commonly used purify ___ obtained by evaporation of sea water or to get crystals of _____ sugar.

Q9 A glass of water is kept on a table. Suddenly few dust paticles fall in it and stat floating on its  

Surface. Which methods out of the following can be used to separate the particles from water    and why?

                                           i.            Sedimentation and Decantation

                                         ii.            Loading

                                       iii.            Evaporation

                                       iv.            Filteration

Q10 Write about the method of Centrifugation.

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