10th (X) Science solved Paper SA Term-1 (Sep)
Q.1. What changes in
the colour of iron nails and copper sulphate solution do you observe after
keeping the iron nails dipped in copper sulphate solution for about 30 minutes?
Ans: Iron nails get
coated with a reddish brown substance. Copper sulphate solution becomes light
green
Q.2. A charged
particle enters at right angles into a uniform magnetic field. What should be
the nature of charge on the particle if it begins to move in a direction pointing
vertically out of the page due to its interaction with the magnetic field ?
Ans: Positive charge
/ Proton
Q.3. What happens
when an aqueous solution of sodium sulphate reacts with an aqueous solution of
barium chloride? State the physical conditions of reactants in which the reaction
between them will not take place. Write the balanced chemical equation for the
reaction and name the type of reaction.
Ans: (i) A white
precipitate / Insoluble substance is formed.
(ii) If the
reactants are in solid state. (iii) Na2SO4
+ BaCl2 Ã
2 NaCl + BaSO4
(iv) Double displacement
/ Double decomposition / Precipitation
Q.4. What is the
main constituent of biogas ? How is biogas obtained from biomass ? Write any
two advantages of using this gas.
Ans: (i) Methane / CH4 (ii) By anaerobic decomposition of biomass in
the presence of microorganisms. (iii) It is a clean fuel. It burns without smoke. It leaves no residue.Its
heat capacity / calorific value is high.
It is used for lighting purpose. Safe and efficient method of waste disposal.slurry left behind
can be used as an excellent manure. (Any two)
Q.5. What is a
solenoid ? Draw the pattern of magnetic field lines of a solenoid through which
a steady current flows. What does the pattern of field lines inside the
solenoid indicate ?
Ans: Solenoid is a
coil of many circular turns of insulated copper wire wrapped closely in the shape of a cylinder.
Draw diagram:
Pattern indicates
that the magnetic field is uniform at all points inside the solenoid.
Q.6. A coil of insulated wire is connected to a
galvanometer. What would be seen if a bar magnet with its north pole towards
one face of the coil is moved quickly towards it, moved
quickly away from the coil and placed near its one face ? Name the phenomenon
involved
Ans: (i) Momentary deflection in the
galvanometer to one side.
(ii) Momentary deflection in the galvanometer, now in the opposite
direction. (iii) No deflection in the galvanometer. Phenomenon
involved is electromagnetic induction.
Q.7. Mention any
four limitations in harnessing wind energy on a large scale.
Ans: Any four of the
following :
(i) It can be used
only at those places where wind blows for the greater part of the year.
(ii) Wind speed
should be higher than 15 km/h to rotate the turbine at the required speed.
(iii) Need of a back
up facility when there is no wind.
(iv) Requires large
area for setting up wind energy farms.
(v) Tower and blades
require a high level of maintenance.
Q.8. No chemical
reaction takes place when granules of a solid, A, are mixed with the powder of
another solid, B. However when the mixture is heated, a reaction takes place
between its components. One of the products, C, is a metal and settles down in
the molten state while the other product, D, floats over it. It was observed
that the reaction is highly exothermic.
Based on the given
information make an assumption about A and B and write a chemical equation for
the chemical reaction indicating the conditions of reaction, physical state of
reactants and products and thermal status of the reaction.
Mention any two
types of reactions under which above chemical reaction can be classified.
Ans: A : Fe2O3 ; B :
Al
(i) Fe2O3(s) + 2 Al
(s) ---Heat-Ã
2 Fe (l) + Al2O3(s) + heat
condition of the
reaction, physical state of reactants and products,thermal status.
(ii) Displacement
Reaction ,Redox Reaction,Exothermic Reaction
Q.9. What is meant
by refining of a metals ? Name the most widely used method of refining impure
metals produced by various reduction processes. Describe with the help of a
labelled diagram how this method may be used for refining of copper.
Ans: Removal of
impurities from a crude metal is called refining of metals.
Description :
On passing the
current through the electrolyte, the pure metal from the anode dissolves into
the electrolyte. An equivalent amount of pure metal from the electrolyte is
deposited on the cathode. The soluble impurities go into the solution, whereas,
the insoluble impurities settle down at the bottom of the anode and are known
as anode mud.
Q.10. Derive the
expression for the heat produced due to a current ‘I’ flowing for a time
interval ‘t’ through a resistor ‘R’ having a potential difference
‘V’ across its ends. With which name is the relation known ? How much
heat will an instrument of 12W produce in one minute if it is connected to a
battery of 12V ?
Ans: (i) Work done
in moving the charge W = VQ
Power input, P =(VQ)/t
= V I
Energy, E = P × t
= V I t
This energy gets
dissipated in the form of heat. H = V I t
Applying Ohm's law,
we get H = I2Rt 2
(ii) The relation is
known as Joule's law of heating.
(iii) P = 12
W t = 1 minute = 60s
H = P × t =
12 W × 60s
H =
720 J
Set-2
1. What change in colour is observed when white silver
chloride is left exposed to sunlight ? State the type of chemical reaction in
this change.
Answer:
White colour changes to grey. Decomposition reaction
2. Which
bases are called alkalis ? Give an example of alkalis.
Answer:
Water soluble bases are called alkalis . NaOH / KOH / Ca (OH)2 / Mg (OH)2 (Any
one)
3. Write
the names and chemical formula of the products formed by the action of chlorine
on slaked lime.
Answer:
Calcium Oxychloride / Bleaching Powder .CaOCl2
4. State
in brief the reaction involved in harnessing nuclear energy from uranium.
Mention any two environmental hazards involved in harnessing nuclear energy.
Answer:
Reaction involved is : Nuclear fission ½
Nucleus
of uranium, when bombarded with low energy neutrons, splits into lighter nuclei
releasing tremendous amount of energy.
Environmental
hazards – (Any two of the following)
(i)
Improper nuclear waste storage and disposal results in environmental contamination.
(ii)
Risk of accidental leakage of nuclear radiations affects the environment.
(iii)
Genetic mutation / Skin cancer
5. What
happens when an iron strip is put into separate beakers containing aqueous solutions
of copper sulphate and zinc sulphate ? Where is iron placed in the activity series
with respect to copper and zinc ? Describe the steps involved in the extraction
of zinc from its sulphide and carbonate ores. Support your answer with balanced
chemical equation for the chemical reactions involved in the process.
Answer:
Colour of copper sulphate solution changes from blue to light green.
Reddish
brown substance is deposited on the iron nail.
No
change is observed in zinc sulphate solution.
Iron
is above copper and below zinc. / Iron is between copper and zinc in the reactivity
series of elements. 1
Roasting
: 2 ZnS + 3 O2 ---Heat------Ã 2 ZnO + 2 SO2
Calcination
: ZnCO3 ---Heat------Ã ZnO + CO2
Reduction
: ZnO + C ------Ã Zn + CO
6. (a)
Give an example of a metal which (i) is
a liquid at room temperature. (ii) is kept immersed in kerosene for storing. (iii)
is both malleable and ductile. (iv) is the best conductor of heat.
(b)
Name the process of obtaining a pure metal from an impure metal through electrolysis.
Suppose you have to refine copper using this process, then explain with the
help of a labelled diagram the process of purification, mentioning in brief the
materials used as (i) anode, (ii) cathode and (iii) electrolyte.
Answer:
a) (i) Mercury / Hg (ii) Na / K (iii)
Cu / Zn / Al / Au / Ag (or any other)
(iv)
Ag / Cu
b)
Electrolytic refining:
Description
: Draw diagram
On
passing current through the electrolyte, the pure metal from anode dissolves
and an equivalent amount of pure metal from electrolyte is deposited on the
cathode. Insoluble impurities settle down at the bottom. (Note : The
description should mention the following: )
Cathode
: Pure copper Anode : Impure
copper
Electrolyte
: Acidified copper sulphate solution
7. Describe an activity to (i) demonstrate the pattern of
magnetic field lines around a straight conductor carrying current, and (ii)
find the direction of the field produced for a given direction of current in
the conductor. Name and state the rule to find the direction of magnetic field
associated with a current carrying conductor. Apply this rule to determine the
direction of the magnetic field inside and outside a current carrying circular
loop lying horizontally in the plane of a table. Assume that the current through
the loop is clockwise.
Answer:
draw diagram
(i) A
thick copper wire is passed through a cardboard and the ends of the wire are
attached to the battery and key. When current is passed through the wire as
shown, the iron filings on tapping the cardboard align themselves in the form
of concentric circles whose centre lies on the wire. On placing a compass
needle at a point (say P) the direction of the north pole of the needle gives
the direction of field at the point P.
(ii)
When the direction of current is downwards the direction of magnetic field
lines is clockwise.
Rule :
Right hand thumb rule
Statement
: Imagine that you are holding a current-carrying straight conductor in your
right hand, such that the thumb points towards the direction of the current,
then your fingers will wrap around the conductor in the direction of magnetic
field lines.
8. What
is electromagnetic induction ? State different ways of inducing current in a coil.
Suggest the most convenient situation for inducing current in a coil. State the
situation in which the induced current in the coil is found to be the highest.
Name and state the rule used to know the direction of the induced current.
Answer:
Electromagnetic induction is the process by which :- a changing magnetic field in
a conductor induces a current in another conductor / motion of a magnet with respect
to the coil produces an induced potential difference which sets up an induced
electric current in the circuit.
Different
ways of inducing current :
(i) by
moving a coil in a magnetic field
(ii)
by changing the magnetic field around a coil
Most
convenient situation :
To
move the coil in the magnetic field.
Condition
for maximum induced current : When the direction of motion of the coil is at
right angles to the magnetic field.
Fleming's
right hand rule : Stretch the thumb,
forefinger and middle finger of right hand so that they are perpendicular to
each other such that the forefinger points in the direction of the magnetic
field, the thumb shows the direction of motion of conductor, then the middle
finger will show the direction of induced current.
9. What
is an ore ? Name the steps involved for obtaining zinc metal from its sulphide ore.
Write the chemical equations for the reactions involved.
Ans: Ore
: A mineral from which a metal can by
extracted profitably
Steps for obtaining
zinc from its sulphide ore :
(i) Roasting
Zn S + O2 -------heating
------Ã
ZnO + SO2
(ii) Reduction
Zn O + C – heating----Ã
Zn + CO ½
10. (a)
State Fleming’s left hand rule. (b) For what purpose is it used ? (c) Name two
devices where this rule is applicable.
Ans : (a)
Fleming's Left Hand Rule : Stretch the thumb, forefinger and middle finger
of your left hand such that they are mutually perpendicular to each other. If
the forefinger points in the direction of magnetic field and middle finger
points in the direction of current, then the thumb will point in the direction
of motion/force on the conducter.
(b)
For finding the direction of force exerted on a current carrying conductor placed
in a magnetic field
(c) Devices:
Electric motor / Electric fan / Electric grinder / Electric meters such as
Galvanometer. ammter etc. (Any Two)
CLASS X SAMPLE PAERS 2013-2014(Sep)
Mathematics SA 1 (with Solution)
1. X MATHSSAMPLE PAER- 1
2. X MATHS SAMPLE PAER-2
3. X MATHS SAMPLE PAER 3
4. X MATHS SAMPLE PAER- 4
5. X MATHS SAMPLE PAER-5
Mathematics SA 1 (with Solution)
1. X MATHSSAMPLE PAER- 1
2. X MATHS SAMPLE PAER-2
3. X MATHS SAMPLE PAER 3
4. X MATHS SAMPLE PAER- 4
5. X MATHS SAMPLE PAER-5
9th science sample paper- S A -1- 2013-1
9th science sample paper-SA1-2013-1-Solution
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9th science sample paper-SA1-2013-2-Solution
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