answers are here
SECTION-A
Ans 1. Combination Reaction. (1)
Ans 2. To protect them from corrosion. (1)
Ans 3. Solar cell. (1)
Ans 4. Ammeter. (1)
Ans 5. Nitric acid is a strong oxidising agent. It oxidizes the hydrogen formed to
water and itself gets reduced to nitrogen oxides.
(1)
Ans 6. Bleaching powder is Calcium oxychloride (CaOCl2). It is prepared by the
action of chlorine on dry slaked lime (Ca(OH)2). (1)
Slaked lime
Uses: 1. It is used for bleaching cotton, linen and wood pulp etc.
(½)
2. It is used for disinfecting drinking water to make it free of germs.
(½)
Ans 7. When an acid reacts with a base of form salt and water, the reaction is called
neutralization reaction.
(1)
HCl + NaOH + → NaCl + H2O
Acid Base Salt (1)
Ans 8. The white solid is quick lime CaO which reacts vigorously with water
producing hissing sound. (1)
The reaction is:
CaO + H2O Ca(OH)2(aq) + Heat (1)
Slaked lime
The product formed is slaked lime Ca(OH)2.
Ans 9. Pancreatic juice contains the enzyme lipase for digestion of fats. (1)
Digestion of fats takes place in small intestine.
(1)
Ans 10. (i) The solar cooker covered with plane glass is more efficient. (1)
(ii) Because plane glass which covers the solar cooker prevents the heat to
escape from solar cooker. (1)
→Ans 11. (a) In series Rs = R1 + R2 + R3 + R4 (½)
4 + 8 + 12 + 24 = 48Ω (½)
(b) In parallel (1)
Rp = 2Ω
Ans 12. The lines drawn in a magnetic field along which a north people would move.
Properties: (1+1=2)
(i) Outside the magnet, magnetic lines of force originate from North pole
and merge at South pole.
(ii) Inside the magnet it is vice versa.
(iii) No two magnetic field lines intersect each other
(any two)
Ans 13. P = V x I = 0.8 x 250 (1)
= 200W
E = P x t =
= 0.2 x 240 (½)
= 48 kWh
Cost 48 x 3 = 144 Rs (½)
Ans 14. (a) Colour of silver chloride is white but
(½)it turns grey in sunlight.
(½)
(b) Decomposition reaction (1)
(c) 2Ag Cl 2Ag + Cl2
White Grey (1)
Ans 15. Chemically, plaster of paris is CaSO4. ½H2O. It is obtained from gypsum
(1)
CaSO4 .H2O on heating at 373K.
Uses of plaster of paris:
(i) Used for making statues. (1)
(ii) Used for setting fractured bone. (1)
Ans 16. White tooth enamel is calcium phosphate which is very hard. It gets effected
when the pH of our mouth falls below 5.5. (1)
The bacteria present in our mouth breaks down sugar and food particles into
acids which damages our teeth. (1)
To prevent the tooth decay, clean the mouth thoroughly after eating with
tooth paste. Tooth paste ch is basic in nature neutralises the excess of acid.
P 1 2 3 4
1 1 1 1 1
R R R R R
= + + +
P
1 6 3 2 1 12 1
R 24 24 2
+ + +
= = = ⇒
200
8 30
1000
× ×
sunlight
→
Ans 17. The path followed by stimulus during the refl
(1)
The brain is not involved in the reflex action, though the information reaches
the brain. Reflex arcs are formed on the spinal cord, although the information
input also goes onto reach the
Ans 18. The first step is the break
Carbon-compound, pyruvate, this process takes place in the cytoplasm and
does not required oxygen. Further oxidation of pyruvate occurs in the
following ways.
(i) In yeast, pyruvate is converted into ethanol and carbon dioxide in the
absence of oxygen.
(ii) In our skeletal muscles, pyruate is converted into lactic acid, when there
is deficiency/lack of oxygen.
(iii) The aerobic oxidation of pyruvate occurs in the mitochondria; the 3
carbon pyruvate molecule gives rise the three molecules of carbon dioxide
and water.
Cytoplasm Cytoplasm
3 carbon 2 carbon
molecule molecule
Glucose Pyruvate Ethanol CO Energy
− −
→ → + +
Cytoplasm Cytoplasm
6 carbon 3 carbon
molecule molecule
Glucose Pyruvate Lactic acid Energy
− −
→ → +
(1)
The path followed by stimulus during the reflex action is called a reflex arc.
The brain is not involved in the reflex action, though the information reaches
the brain. Reflex arcs are formed on the spinal cord, although the information
input also goes onto reach the brain.
The first step is the break-down of glucose, 6Carbon-compound into 3
compound, pyruvate, this process takes place in the cytoplasm and
does not required oxygen. Further oxidation of pyruvate occurs in the
) In yeast, pyruvate is converted into ethanol and carbon dioxide in the
absence of oxygen.
(ii) In our skeletal muscles, pyruate is converted into lactic acid, when there
is deficiency/lack of oxygen.
(iii) The aerobic oxidation of pyruvate occurs in the mitochondria; the 3
carbon pyruvate molecule gives rise the three molecules of carbon dioxide
Cytoplasm Cytoplasm
No oxygen 2
3 carbon 3 carbon 2 carbon
molecule molecule molecule
Glucose Pyruvate Ethanol CO Energy
− − −
→ → + +
Cytoplasm Cytoplasm
6 carbon 3 carbon
No oxygen 3 carbon
molecule molecule molecule
Glucose Pyruvate Lactic acid Energy
− − −
→ → +
ex action is called a reflex arc.
(1)
The brain is not involved in the reflex action, though the information reaches
the brain. Reflex arcs are formed on the spinal cord, although the information
(1)
compound into 3
compound, pyruvate, this process takes place in the cytoplasm and
does not required oxygen. Further oxidation of pyruvate occurs in the
) In yeast, pyruvate is converted into ethanol and carbon dioxide in the
(½)
(½)
(ii) In our skeletal muscles, pyruate is converted into lactic acid, when there
(½)
(½)
(iii) The aerobic oxidation of pyruvate occurs in the mitochondria; the 3-
carbon pyruvate molecule gives rise the three molecules of carbon dioxide
(½)
Glucose Pyruvate Ethanol CO Energy → → + +
2
Glucose Pyruvate Lactic acid Energy (½)
Ans 19. The dead remains of plants, animals and agricultural waste is called biomass.
(1)
(1)
Constituents: (1) Methane
(2) Hydrogen
(3) Hydrogen Sulphide
(4) Carbon dioxide (1)
Ans 20. I1 = A = 1.2A (½)
I2 = A = 0.6A (½)
I3 = A = 0.2A (½)
I = I1 + I2 + I3 = 2A (½)
Total resistance
(1)
Cytoplasm Mitochondria
No oxygen 2 2
6 carbon 3 carbon
molecule molecule
Glucose Pyruvate CO H O Engery
− −
→ → + +
6
5
6
10
6
30
P
1 1 1 1
R 5 10 30
= = = +
6 3 1
10
+ +
=
P
1 10 1
R 3 3
= =
R 3 P
= ΩAns 21. Resistance mean obstruction in flow of current (1)
Length = L Area of Cross section = A
L’ = 2L A’ =
R’ = R’ = (1)
R’ =
R’ = 4R
Resistivity of wire will be same. (1)
Ans 22. H = I
2
Rt (3)
R = =
= 3Ω
Ans 23. (a) Copper is extracted from its sulphide ore (Cu2S) by heating it in air
strongly. The steps of copper extraction are as follows:
(b)
Electrolytic refining of copper: In this process, the impure copper metal is made the anode
and a thin strip of pure copper metal is made cathode. An acidified solution of
copper sulphate is used as electrolyte. On passing the current through
electrolyte, pure copper from anode dissolves into the electrolyte and an
equivalent amount of pure metal is deposited from electrolyte on cathode.
The soluble impurities go into the solution while the insoluble impurities settle
down at the bottom of anode and known as anode mud. (5)
A
2
L
A
ρ
L '
P
A '
'
'
L
A
ρ
' 2L
R
A
2
= ρ
L
4P
A
L
A
ρ
8
8
12 3.14 10
3.14 4 10
−
−
× ×
× ×
2 (s) 2 2 (s) 2(g)
2 2 (s) 2(g)
2Cu S 3O 2Cu O 2SO
2Cu O Cu S 6Cu SO
∆
∆
+ → +
+ → +OR
(a)
where represents the number ofvalence shell
electrons. (5)
(b)
(c) Three properties of ionic compounds are:
(1) High melting and boiling point
(2) Hard Crystalline solid
(3) Conductors of electricity in aqueous state. Ans 24.
(a) (1)
(b) (i) Midbrain controls many of the involuntary actions. (1)
(ii) Hind brain: It has three parts
(a) Pons: it has centre for regulating the breathing rhythm. (1)
(b) Medulla: it controls is involuntary functions like blood pressure,
salivation, vomiting etc. (1)
(c) Cerebellum: it is responsible for (1)
(i) precision or coordination of voluntary actions
(ii) maintaining the posture and balance of the body.
OR
(a) Insulin – Regulates sugar metabolism/maintain blood sugar level (1)
Glycogen, Increases blood sugar level. (1)
(b) When adrenaline is produced, the hormone increases blood supply to
heart and skeletal muscles. It constricts arterioles and blood supply to skin and
gastrointestinal tract. The bronchioles dilate. There is increased rate of breathing,
oxygenation and heart beat to meet any emergency. (1)
(c) The timing and amount of hormone released are regulated by feedback
mechanism. (1)
Ex. When sugar level in blood rises – more insulin is secreted. Insulin
removes extra glucose from blood by converting into glycogen.
Falling glucose level reduces insulin secretion by pancreas (1)
Ans 25. (a) When a metal body of any electrical appliances is connected to a metal
wire dipped inside the earth it is said to be earthed. It is necessary to earth
all electrical appliances to avoid unwanted electrical shock.
(b) (i) An electric circuit is said to be short circuited if live wire and neutral wire come in contact with each other.
(ii) Over loading means to connect too many appliances with single socket
and using faulty device in electrical circuit. (5)
OR
(a) According to Fleming’s left hand rule, let the thumb, forefinger and central
finger of the left hand be stretched so that they are mutually perpendicular to
one another. If the forefinger points in the direction of the magnetic field and the
central finger points in the direction of a current, the thumb gives the direction of the
force acting on the conductor.
(b) (i) When bar magnet is pushed into the coil, due to
electromagnetic induction an induced current is produced. The galvanometer will
show deflection.
(ii) Same as above but deflection will be in opposite direction.
(iii) No deflection. (5)
SECTION-B
Ans 26. (a) (1)
Ans 27. (d) (1)
Ans 28. (d) (1)
Ans 29. (d) (1)
Ans 30. (a) (1)
Ans 31. (c) (1)
Ans 32. (b) (1)
Ans 33. (b) (1)
Ans 34. (a) (1) Ans 35. (c) (1)
Ans 36. (b) (1)
Ans 37. (b) (1)
Ans 38. (d) (1)
Ans 39. (c) (1)
Ans 40. (d) (1)
Ans 41. (a) (1)
Dear Student!!
I could not interpret your query. Please be a little specific so that I could provide you meaningful help.