CLASS VIII
SUBJECT SCIENCE
CH MICROORGANISM
1..I made the first vaccine. Guess who am I?
2.Microbes will never grow on food kept inside
refrigerator. Do you agree? Why?
3.a).What is food spoilage?
b).What are the various methods of food
preservation? Explain in detail any four
4. a).How vaccines help in preventing diseases?
b).Name the diseases (any two) against which
vaccines offer prevention.
5.Identify
the microorgnisms shown in the diagram
CH FORCE AND PRESSURE
1.
A force acts perpendicular to given surface..What is the quantity ‘force per unit area’ known as?
.2
A comb rubbed against dry hair, clings
to the bits of paper due to ______force.
. 3.When a person lifts a bucket full of water
against the ground, how many forces are acting on it?Name the forces.
.4.Calculate the pressure exerted by an object
applying force of 60N on 600m2 area.
5.i)What
do understand by Atmospheric pressure?Write one experiment to show that air exerts pressure in all
direction.Draw the diagram also to explain your answer.
6.Give one example
of a situation in which applied force causes a change in the speed of an
object.
7.Describe an experiment to show that air
exerts pressure in all directions. Draw
a well labelled diagram also.
.8. In the following
statements identify the agent exerting the force and object on which its acts.
State the effect of the force in each case.
(a) Squeezing a piece of lemon between the fingers
to extract its juice.
(b) Taking out paste from a toothpaste tube.
(c) A load suspended from a spring while its other
end is on a hook fixed to a wall.
(d) An athlete making a high jump to clear the bar
at a certain height.
CH FRICTION
1.
Friction
causes production of ________energy.
2.
Encircle the odd one out and give reason :
Oiling,streamlining,ball
bearing,grooves
3.
Rewrite
the correct statement :
Rolling friction is less than sliding friction.
4. Does air exert friction on an object moving
through it?
5. Friction
causes wastge of energy.(true/False)
6. Look at the picture and explain what is
depicted by this picture..Also write the conclusion of the activity
demonstrated through the picture.(30 -40
words)
8. ..give reason:
a). Suitcase is provided with wheels
b) Manjari tries to hold a glass with oily
hand,it slips from her hand.
c)School bags have broader strap.
Ch:
Reflection of light
Q1
Light is falling on three surfaces S1, S2 and
S3 as shown. In which case angle of incidence would be equal to angle of
reflection. Support your answer with reason
Light is falling on three surfaces S1, S2 and
S3 as shown. In which case angle of incidence would be equal to angle of
reflection. Support your answer with reason  |
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S1 S2 S3
Q2
a) The
distance between the object and its image formed by a plane mirror appears to
be 24cm. What is the distance between mirror and object?
b) If the object shifts 10cm towards the mirror what will
be the distance between object and image?
Q3)
Jatin stood in between two plane
mirrors to see his image? How many images he would see? Where are such parallel
mirrors used?
Q4) Look at the diagram and answer
a)
Which
phenomenon is depicted in the figure?
b)
Define
the process
c)
What
will we obtain on white screen ?
d)
Write
the sequence of colours.
e)
Mention
where else you see this phenomenon?
Q5Give reason why
a)
We cannot see
stars during the day
b) Red light is used as traffic signal for stopping the
vehicles.
ch
Metals and Nonmetals
Q1) Some elements have properties of both
metals and nonmetals. What are they called? Give two examples and their use
Q2)
Gold and silver are used to make jewellery .Why? Give two reasons to
support your answer
Q3) Purnima took two test tubes and labeled
them A&B as shown
A B
In test tube A she puts a substance X and dilute HCl. In
test tube B she puts Y and added dil HCl .Reaction starts taking place in test
tube B with evolution of a gas. No such chemical reaction is observed in test
tube A
a)
Which
of these substances “X” and “Y” do you think is a metal? Give reason for your answer
b)
Which
gas is evolved in test tube B?
Q3 Name
a) metal which is liquid at room temperature
b)
most abundant element on earth after oxygen
c) element used for making
matchsticks or crackers
Q 4 Write the reactions for the following
a)
Magnesium
when burnt in oxygen
b)
Zinc
hen added to hydrochloric acid
Q5)
.
Look at
the diagram and answer
a)
The
portion of grey nail which is inside the blue solution of copper sulphate
becomes --------------
b)
The
change of colour of nail happens because
--------------
c)
Blue
colour copper sulphate changes to ------------ colour
d)
The
activity shows that -------------
e)
Write
the chemical reaction for this activity
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