10th science sa-1 question paper 2017-18
9th Mathematics sa-1 question paper 2017-18
1oth Mathematics sa-1 question paper 2017-18
9th science sa-1 question paper 2017-18
10th science sa-1 question paper 2017-18
9th Mathematics sa-1 question paper 2017-18
1oth Mathematics sa-1 question paper 2017-18
SA1 question paper class 9 and 10th 2017-18
DAV sample question papers with Marking Scheme class - VIII (Term - I & II) 2017-18
In order to enable the teachers and students to prepare well for the Annual
Examination at the end of the academic session 2017-18, the DAV Centre for
Academic Excellence provides Sample Question Papers. It is hoped that these
sample question papers will certainly improve the classroom transaction of the
subject matter in our schools. These Sample Question Papers have been prepared
by practicing teachers of DAV Public Schools under the guidance of experienced
resource persons in workshops conducted by the DAV Centre for Academic
Force and Pressure Class 8 Living Science Solution
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8th Reflection of sound_living science answer
8th chemical effect of current living science solution
8th Refraction and dispersion living science solution
Class8 Natural phenomena (living Science) answer
8th Our universe living science solution
8th Synthetic Fiber_plastic (Living science answer)
8th Metals and Non metals solution(living science)
8th combustion and flame living science solution
8th Coal and Petroleum solution(living science)
8th Pollution of water and air living science solution
9th gravitation Extra score solved Questions
P. 71 Oral Questions For Formative Assessment (Living Science)
1. acetic acid and citric acid
2. Acids are corrosive in nature. Strong acids can corrode even metals like iron and aluminium. Hence, acids are not stored in metal containers.
3. litmus paper and methyl orange; acid-base indicators
4. neutralization reaction, salt
5. Organic acids are naturally occurring acids that are present in animal and plant products. They are normally weak acids. Hydrochloric acid, sulphuric acid and nitric acid are known as mineral acids. They are normally strong acids.
P. 72 Oral Questions For Formative Assessment
1. Bases which are soluble in water are called alkalis. But some bases are not soluble in water, so they are not alkalis. That is why all alkalis are bases but all bases are not alkalis.
2. I will not recommend that quicklime or slaked lime be added to the soil to neutralize the acid present in it.
3. sodium hydroxide (NaOH)
4. hydrochloric acid (HCI), magnesium hydroxide is used as an an acid to neutralize the excess add in the stomach
P. 74 Oral Questions For Formative Assessment
1. If we replace hydrogen of an acid with a metal, a salt is formed.
2. a salt and water
3. a. nitric acid
b. carbonic acid
c. hydrochloric acid
d. sulphuric acid
4. a salt; sodium bicarbonate (NaHCO3)
Page 74 For Formative and Summative Assessment
A. 1. d 2.a 3.c 4. d 5. c 6. a 7. d 8. d 9. b
B. 1. sodium chloride 2. an acid 3. red 4. false
5. nitric acid
6. lactic 7. carbon dioxide 8. neutralization 9. sulphuric add 10. alkali
11. ammonium hydroxide
12. a base 13. pale yellow 14. caustic soda 15. magnesium hydroxide
16. true 17. blue
C. 1. The substance which can be used to test if a given substance is acidic or basic in nature is known as an acid-base indicatdr, for example, methyl orange.
2. lemon, antacid, common salt 3. When dilute sulphuric acid is added to zinc, hydrogen gas is produced along with zinc sulphate.
4. Dilute acids react with carbonates such as calcium carbonate (CaCO3) to form salt and carbon dioxide gas.
5. Examples of strong acids: (I) Nitric acid (ii) Sulphuric acid
Examples of weak acids: (i) Lactic acid (ii) Acetic acid
6. Ant bite injects formic acid inside the skin, and thus skin irritates for some time. To get relief, a base (baking soda) is applied to neutralize the acid. The irritation ends with forming salt and water and provides relief.
7th Acids bases and Salt Living science solution
For Formative and Summative Assessment
A. 1. b 2. a 3. d 4. b 5.d 6. a 7. c 8. b
B. 1. Biodiversity means the variety of plants, animals and microorganisms generally found in an area.
2. `Flora' refers to plants.
3. Yes - I agree
C.1. Biodiversity is the variety of plants, animals and microorganisms generally found in an area.
2. Flora: Species of all plants found in a particular area is known as flora of that area. Fauna: Species of all animals found in a particular area is known as fauna of that area.
3. Cutting down forests and using the land for other purposes is known as deforestation.
4. Some animals cannot adjust to the environmental changes and begin to die. These animal species become endangered as their population becomes very small.
5. A biosphere reserve is a large protected area set aside for conservation of wildlife, plant, animal and microorganism resources, and the traditional life of the tribals living in that area.
6. Endemic species are those species of plants and animals that are found exclusively in a particular area and are not naturally found anywhere else. For example, the Indian giant squirrel and flying squirrel are endemic to the Pachmarhi Biosphere Reserve area.
7. IUCN prepared Red Data Book to highlight those animals who are threatened with extinction, with the aim of promoting their conservation. Those threatened with extinction.
8th Conservation of plants_animal science solution
Q. 26. How is pressure developed in a container full of a gas ?
Gaseous molecules are free to move in the container. The molecules collide with each other and with the wall of the container. On the wall the molecules exert force. The force per unit area is called the pressure of the gas.
Q. 27. What are the applications of interconversion of states of matter ?
The inter conversion of states of matter is used to :
(i) generate electricity in thermal power plant.
(ii) separate nitrogen and oxygen from air by liquefaction.
(iii) prepare machine parts.
(iv) prepare room fresheners.
(v) prepare ice-creams.
Q.28. What happens to a gas if its inter molecular space is reduced ?
If the inter molecular distance between molecules of a gas is reduced, it changes to liquid. Further reduction it is changed to solid.
Q. 29. Which of the following substances is most compressible?CO2, H2O, NaCl.
Q. 30. Which property of a gas results in steady pressure of the gas ?
Answer: The constant bombardment of the gas molecules with the walls of the container
Q. 31. In which of the following substances, weakest inter molecular force is expected: H2O, CH3OH,
Answer: Al, He. He
Q. 32. One gas mixes with another gas easily. What is this property called ?
Q. 33. Describe briefly (i) Melting point and (ii) Boiling point.
(i) Melting point :- The melting point of a solid is that temperature at which it changes into the liquid. From the beginning to the end of melting, the temperature does not change.
(ii) Boiling point :- The boiling point of a liquid is that temperature at which a liquid starts boiling at the atmospheric pressure.
Q. 34. How would you find out whether a sample of sodium chloride is pure or impure ?
Answer: Pure substance melts at its melting point. If sodium chloride melts at 97ºC,then the sample is pure otherwise impure.
Q. 35. How will you find out whether a sample of water is pure or impure ?
Answer: The boiling point of water at one atmospheric pressure is 100ºC. If the given sample of water boils at 100ºC then it is pure otherwise impure.
Q. 36. Why do solids have a fixed shape and gases have neither a fixed shape nor a fixed volume ?
Answer: In solids the molecules are close due to intermolecular force. The molecules are arranged in a fixed pattern. The movement of molecules are not possible. Hence its shape are fixed .
In gases the intermolecular force are negligible. Molecules are free to move in any direction. The distance between the molecules is very large. Hence gases do not have fixed shape and fixes volume.
Q. 37. What is Vaporization ?
Answer: The change of liquid into its gaseous form (vapour) when temperature of liquid is increased is called vaporization.
Q. 38. What is Sublimation ?
Answer: A change of state directly from solid to gas without changing into liquid state or vice-versa is called sublimation.
Q. 39. What is Condensation ?
Answer: A change of gaseous state to liquid state or solid state is called condensation.
Q. 40. What is Deposition ?
Answer: A change of vapour to solid is called deposition. It is the reverse process of sublimation
Q. 41. What is Liquefaction ?
Answer: A substance which is gas in normal condition, when changed to liquid by cooling it under pressure is called liquefaction.
Q. 42. What is Solidification ?
Answer: A substance which is a liquid in normal condition, when changed to solid to by cooling it under pressure is called solidification.
Q. 43. What is difference between vapour and gas.
Answer: Vapour is used to denote the gaseous state of fluids which exists as liquids under normal conditions, while gas is used to denote the gaseous state at normal temperature. We always speak water vapour and carbon dioxide gas.
Q. 44. Why do the three states of matter differ ?
Answer: The three states of matter differ due to :
(i) Difference in packing and arrangement of molecules in the three states.
(ii) Intermolecular force of attraction are different in the three states.
Q. 45. Why does the temperature remain constant until whole of the solid changes into liquid, though the heat energy is constantly supplied ?
Answer: During melting, temperature of the liquid phase remains the same as that of the liquid phase. The heat energy supplied is utilized to destroy the crystal pattern and is stored in the liquid phase as potential energy.
Q. 46. Why does the temperature remain constant during boiling though heat is constantly supplied ?
Answer: The heat energy supplied is utilized to destroy the intermolecular force amongst the molecules of the liquid and is stored as potential energy.
Q. 47. Why does a gas fill a vessel completely ?
Answer: The molecules of a gas are moving continuously with a high speed in all direction and intermolecular force amongst the molecules are negligible. Hence it fills the vessel completely.
Q. 48. How does the state of matter changes from solid to liquid and then to gas on heating ?
Answer: In solids particles are very close. When heat is given to solid, the distance between particles increases and it takes the shape of the container. On further heating the distance between the particles increases in such an extent that the molecules are free to move. This is a gaseous state.
Q. 49. Explain the term boiling on the basis of kinetic theory of gases.
When a liquid is heated up to its boiling point, the heat is absorbed by the molecules and stored in the form of potential energy . When potential energy of the molecule is is increased, the intermolecular distance is increased. It means intermolecular force of attraction reduces to zero. The molecules start escaping in air causing the liquid to boil.
Q. 50. Explain the term melting on the basis of kinetic theory.
Answer: The molecules of solids vibrate about its mean position. When it is heated, its kinetic energy is increased and it starts vibrating vigorously. At the melting point the intermolecular force of attraction is reduced and particles can not hold each other with strong force to hold them in their fixed position. The crystalline structure is destroyed and it starts melting.
Matter in our surrounding solved questions class9 Step-01 Read_Download
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CBSE - Class X Examination 2017 Announced on 03rd June 2017
Q. Mention one reason why tungsten is used for making filament of electric lamp. [CBSE 2014]
Ans: tungsten does not oxidize, i. e. burn easily at high temperatures as it has higher melting and boiling point than metals
Q. List two characteristics of the material to be used in fuse wire. Name the material it is made of. A fuse is always connected in series in an electric circuit ? Justify this statement giving reason [CBSE 2014]
two characteristics of the material to be used in fuse wire
(a) Low melting and boiling point (b) high electric resistance
Fuse is generally made up of an alloy of tin and lead
In series connection the current for the entire house pass through the fuse. So, when fuse melts , it breaks down the entire home circuit and no current flows to the household circuitry. Thus, a fuse is always connected in series
Q. A circuit has a line of 5 A. How many lamps of rating 40 W; 220 V can simultaneously run on this line safely ?[CBSE 2014]
Solution : P = VI so, I = P/V = 40/220
No of lamp can simultaneously run on this line safely = 5A/(40/220 )A = 27
Q. Several electric bulbs designed to be used on a 220 V electric supply line, are rated 10 W. How many lamps can be connected in parallel with each other across the two wires of 220 V line if the maximum allowable current is 5 A?
Resistance R 1 of the bulb = V^2/p1 = (220)2/10 = 4840 Ohm
Let lamps can be connected in parallel with each other
According to O hm’s law, V = I R
Where, R is the total resistance of the circuit for x number of electric bulbs
R = V/I = 220/5 = 44 Ohm
Number of lamp = 4840/44 = 110
Q. Express work done in an electric field in terms of charge and potential difference. Calculate the amount of work done in carrying a charge of 5 mC against a potential difference of 100 V [CBSE 2014]
Solution : Work dome = charge x potential difference
the amount of work done in carrying a charge of 5 mC against a potential difference of 100 V = 5 × 10^3 × 100 = 0. 5 J
Q. Distinguish between kilowatt and kilowatt hour. For a heater rated at 4.4 kW; 220 V . Calculate the -
(i) current drawn by the heater (ii) resistance of the heater element
(iii) energy consumed by the heater in 5 hours (iv) cost of running the heater if 1 kWh costs Rs. 6.50 [CBSE 2014]
Answer: Kilowatt is the unit of Power where as KiloWatt Hour is the commercial unit of energy.
Given, P = 4.4 kW = 4400 W and V = 220 volts
(i) As P = V /I So, I = P/V = 4400/220 = 20 A
(ii) As P = I^2R So, R = P/I^2 = 4400/(20) 2 = 11 ohms
(iii) since, electric energy = electric power X time = 4.4 kW X 4 hours = 17.6 kWh
(iv) Since, 1KwH costs Rs. 6.50, hence, costs of 17.6 kWh = 17.6 X 6.50 = Rs. 114.4
Q.Distinguish between resistance and resistivity of a conductor.
The resistors are generally made of thin wires of Eureka or Manganin while the wires used in connections are made comparatively thicker and are of copper or aluminium. Why ? Give reason.
What would happen to the resistance of a wire if it is stretched to double its length ? Justify your answer.[CBSE 2014]
1. It is the measure of a material’s ability to oppose the flow of current.
2. It depends on the property of the material. Its value is constant for a particular range of temperature.
3. Unit of resistivity is Ohm meter
1. It is a measure of the opposition that a circuit (or an electrical element) offers to the flow of electric current.
2. Resistance of a conductor is directly proportional to its length and inversely proportional to its area of cross section.
3. Unit of resistance is Ohm
The resistors are generally made of thin wires of Eureka or Manganin while the wires used in connections are made comparatively thicker and are of copper or aluminium. This is because thicker wire has less resistance than thinner wire
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