C L,+SS x P)47Stcs

: : CBSE QUESTION BANK

Question Bank from ELECTRICITY1. What is the Sl Unit of electric Potential?2" What do you mean by the statement; "The electric potential between the

pointsAandBislV"?3. There are two electric bulbs, one marked 60W 22AV and the other marked

100W 220V . Which one of the two has a higher resistance?4. Of the two; a toaster of 1 kW and an electric heater of 2 k\l/, which has higher

resistance?

5. Name a metal which offers higher resistance to the passage of electricity thancopper.

6. calculate the ratio of resistances of a 50w bulb and a 25 w bulb.7. Why is tungsten preferred to make the filament of an incandescent lamp?8. A wire of resistance 10 Ω is bent in the form of a circle. What is the

effective resistance between the two points at the ends of any one of thediameter of the circle?

9" What is mean by saying that the "potential difference between two points is 1

volt".

10. Define electric power. What is its S.l. unit?11. A wire of resistivity p is stretched to twice its length. What is new resistivity?

(1 mark)12. Define the unit "ohm".

13. Name a device that helps to maintain a potential difference across aconductor.

14. Define resistivity. Write the S.l. unit of resistivity.15. Will current flow more easily through a thick wire or thin wire of the same

material when connected to the same sources? Why?16. A wire of resistance 10 Dlis drawn out so that its length is thrice its original

length. Calculate(i) lts new resistance (resistivity and. density of the wire remain

unchanged).(ii) Define resistivity and state its S.l. unit. Does it its value vary with

temperature.17. What are the factors on which the resistance of a conductor depends? Give

the corresponding relation.18. What is voltmeter? How is it connected in a circuit?19. Three resistors R1, R2 an R3 are connected in parallel. Find their equivalent

resistance (resultant resistance)"

2A

f,::lJ: ;';'j'f^,^:1'j::l' *l:, do vou understand bv the21" t.

d i re cti o nrcr

:o "_

^:,:*.:j.",,," nt ? ;; ;. ;"J # : JX:.. g. jH co n ve n t i o n a r

electrical appliance depends.I:ffi jn5:::;11.'il,1n,.'lT:ilf [,il:,x"J,::X,,"0 by an

l:Ir?'"n of the fo'owing cases more erectricar ener.gy is consumed per

a' A current of 1 ampere passed through a resistance of 300b'

ilfft"r, of 2 amperes passed throush a resisrance of 100

22' (a) what is meant by 'Erectric Resistance, of a conductor?(b) A wire of length L and resistance n i* .trut"hed so that its length isdoubred and the area of cross-section i, harved. How wi, its.(i) resistance change?

- (ii) resistivity change?2s' '.Hil:::tances

n.,, nirrd R3 are joined in series. Find their equivarent24 ,:'i:?X$lili;,i"'cribe an experiment with a neat rabered circu* diagram

Magnetic Effects of Electric Current1. Why natural magnet *r, .r,*O Lodestone?2. Write two common properties of magnet"3. Can you make a magnet n*in4. Define magnetic fieto tg a north pole only?

ii.

5.

6.

7.

8.

L10.

11.

12.

13.

14.

What are magnetic field lines?Draw magnetic field lines around a barmagnet.Write two properties of ,rgn"ti" flrcld lines.

[]:,n;t^e shape of magnetic fierd rines around a straight conductor carrying

State right hand grip rule.State two factors on which the strength of magnetic fierd at a point due to a. current carrying conductor depends..

'Draw a diagram of magnetic fierd rines due to current ciWhat is a solenoid? arrying circular loop

|jffi:agram showing the pattern of fierd rines around a current carrying

state the factors affecting the strength of magnetic fierd due to a sorenoid.

40

15.

16.

17"

18"

19.

20.21.

22.

23.24.

25.26.

zt-28.29.30"

31.

32"

33.

34.35.

36.

How will you determine the polarity of a solenoid from the direction ofcurrent?What is an electromagnet?How can we increase the strength of an electromagnet?State Fleming's left hand rule.

What is an electric motor?State the principle of working of an electric motor.What is electromaEnetic induction?What is magnetic flux?

State Fieming's right hand rule.

What is an electric generator or a dynamo?Write the differences between ac and dc dynamo.How is the alternating current produced in a dc generator converted to dc inthe output?Write the advantages of AC over DC.

Write the color coding of wires in domestic circuits"Why is switch connected always to the live wire only?What is an electric fuse? Explain its rnorking.

What is earthing?

Explain the terms "short circuiting" and "Over Loading"?What are the materials used for making electric fuse and explain why?State SNOW rule.

Draw diagram showing (i) uniform magnetic field (ii) Non uniform magneticfield.Draw a schematic diagram showing typical domestic wiring.

SOURCES OF ENERGY1. "Energy can neither be created nor be destroyed". Then why do we talk about

'Energy Crisis"?

What do you mean by "transformation of Energy"?State the law of conservation of energy.Write the characteristics of a good source of energy.What are the criteria for selecting a good fuel?What are fossil fuels?What are renewable and non renewable sources of energy?How can we decrease pollution caused by burning of fossil fuels?Write the advantages and disadvantages of fossil fuels.How is electrical energy produced in thermal powerplant?

How is electrical energy produced in hydel powerplant?

41

COLLECTION OF HOTS QUESTIONS

ELECTRICITY1. Why effective resistance is decreased when resistors are connected in

parallel

2. Explain the principle behind Faraday's Experiments on electromagnetic

induction

3.

4.

5.

6.

7.

Why Ohm's law does not hold good under conditions of varying temperature?

lf a wire of length I and area of cross section A is fused with a similar wire to

double its length, then what will be the new (a) resistance (b) Resistivity

How many KWh s make 1 joule?

How can you make a 3 O resistance by combining with a number of 2 Q

resistors available with You.

Four resistances 2.0 A each are connected end to end to form a Square

ABCD. Calculate the equivalent resistance of the combination between: (i)

any two adjacent corners (ii) any two opposite corners'

MAGNETIC EFFECTS OF CURRENT

1.

2.

lf a magnetic needle is Placed at

direction wilt it show? Why?

A wire hidden inside a wall carries

the wire is horizontal or vertical?

the North Pole in horizontal plane, which

a current. How will yoiu find out whether

1i.a:

::it'atit..i:r':'i:l:

HOLIDAY ASSIGNMENT

CLASS X (BIOLOGY)

Term I

Life Processes

Q.1. Why do aquatic animals breathe faster than the terrestrial animals?

Q.2. What advantage over an aquatic organism does a terrestrial organism have

with regard to obtaining O2 for respiration?

Q.3. What will be the outcome if a farmer floods his field every day?

Q.4 Due to availability of less water, how does the plant cope up with lack of water

in desert conditions?

Q.5 Food moves down the food pipe by peristalsis. Which region controls

peristalsis?

Q.6 Which equipment is used to facilitate breathing during serious breathing

problems?

Q.7 Tooth enamel is one of the hardest substances in our body. How does it

undergo damage due to eating chocolates and sweets?

Q.8 "If there are no algae there would be no fish in the sea" comment.

Q.9 Why does leaf appear green?

Q.10 What is the role of light in photosynthesis?

Q.11 In which direction does lymph flow?

Q.12 Why does anaerobic respiration produce less energy compared to aerobic

respiration?

Activity to be performed during holidays.

1 TO enable students learn opening and closing of stomata.

2. You must have heard about genetically modified foods. Find out from internet

and other sources about the nutritional value of GM food make a report

stating both the advantages and disadvantages of GM food.

CLASS X

CHEMICAL REACTIONS AND EQUATIONS

Q.1. What type of reactions are represented by the following equations ?

(a) A + B AB (b) C A+ B

(c) AL + X AX + L (d) AB + CD AD + CB

(e) Cl2 + 2KI 2KCl + I2 (f) 2 Mg + O2 2 MgO

(g) 4HNO3 4NO2 + 2H2O + O2 (h) AgNO3 + HCl AgCl + HNO3

Q.2. A Shiny brown substance X on heating in air turns black and a new compound Y

is formed. Name the substance X and black compound Y.

Q.3. Why oily and fatty food items are flushed with nitrogen gas ?

Q.4. Name the substances oxidized, reduced, oxidizing agent and reducing agent in

the following reactions :

(i) Ca + Cl2 CaCl2

(ii) 3MnO2 + 4 Al 3 Mn + 2Al2O3

(iii) Fe2O3 + 3CO 2 Fe + 3CO2

(iv) Fe + S FeS

Q.5. Gold and silver do not corrode in moist air. Give reason.

Q.6. (a) Does rusting represents oxidation or reduction of Iron ?

(b) Which process is responsible for the rancidity of fatty foods ?

(c) Write the main purpose of painting iron gates .

(d) Where butter will become rancid ? (i) in refrigerator (ii) on shelf in the kitchen

Q.7. Give an example to explain that oxidation and reduction occur simultaneously.

Q.8. What is meant by photo-decomposition reaction ? Give on example.

Q.9. A solution of a substance ‘X’ is used for testing CO2. Identify ‘X’. What will be its

reaction with CO2 ? Write balanced chemical equation for the reaction.

Q.10. What happens when ferrous sulphate crystals are heated? Explain with the help

of chemical equations. What type of reaction it is ?

CHAPTER2

ACIDS AND BASES

Q.1. Yellow spot of turmeric on clothes turns brown when it comes in contact with

water and soap. why ?

Q.2. Give one example of each of the of following :

(i) A basic oxide which is soluble in water what is the formula of the compound.

(ii) A hydroxide which is highly soluble in water.

(iii) A basic oxide which is insoluble in water.

(iv) A hydroxide which is insoluble in water.

Q.3. Do basic solutions also contain H+ (aq) ions ? If yes , then why are these basic ?

Q.4. Under what soil condition a farmer would treat the soil of his field with quick lime

or slaked lime or chalk ?

Q.5. The pH values of solutions marked A, B, C, D and E are 4, 1, 11, 7 and 9

respectively.

(i) Arrange these solutions in the decreasing order of pH values .

(ii) Arrange these solutions in the increasing order of hydrogen ion concentration

(iii) In the list of the given solutions identify :

(a) Neutral solution (b) highly alkaline solution

(c) highly acidic solution (d) less acidic solution

(e) Less basic solution

Q.6. What can you say about the pH of a solution that liberates CO2 from sodium

carbonate.

Q.7. How would you distinguish between baking powder and washing soda by

heating?

Q.8. Salt A commonly used in bakery products on heating gets a converted into

another salt B which itself is used for removal of hardness of water and gas C is

evolved. The gas C when passed through lime water, turns it milky. Identify A,

B.and C .

Q.9. What happens when nitric acid is added to egg shell ? Give equation also.

Q.10. What are strong and weak acids ? In the following list of acids, separate strong

acids from weak acids

HCl, citric acid, acetic acid, nitric acid, formic acid, sulphuric acid

Chapter 3

METALS AND NON METALSS

Q.1. A student was given Mn, Zn, Fe and Cu metal. Identify which of them

(a) will not displace H2 from dil. HCl

(b) will react only with steam to give H2 (g)

(c) will give H2 with 5% HNO3

Write the chemical reactions involved.

Q.2. A metal ‘X’ loses two electrons and a non metal ‘Y’ gains one electron. Show the

electron dot structure of compound formed between them. Is it ionic or covalent ?

Does it have high melting point or low ? Will it conduct electricity is solid state or in

aqueous solution and why ? Will it be soluble in water ?

Q.3. What is 24 Carat gold ? How will you convert it into 18 carat gold ?

Q.4. Give reasons :

(a) Aluminium oxide is considered as an amphoteric oxide

(b) Ionic compounds high melting points

Q.5. Give reasons for the following observations :

(a) Zinc fails to evolve hydrogen gas on reaching with dilute nitric acid.

(b) Metal sulphides occur mainly in rocks but metal halides occur mostly in sea and

lake waters.

Q.6. Why electric wires are covered with rubber like material ?

Q.7. From dilute hydrochloric acid, zinc can liberate hydrogen gas but copper can not .

Why ?

Q.8. Why is sulphide ore of a metal is first converted to its oxide to extract the metal

from it ?

Q.9. An ore on heating in air produces sulpher dioxide. Which process would you

suggest for its concentration. Describe briefly any two steps involved in the

conversion of this concentrated ore into related metal.

Q.10. Explain why

(a) Reactivity of Al decreases if it is dipped in HNO3

(b) Carbon can not reduce the oxides of Na or Mg.

SA – 2, CHAPTER 4

CARBON AND ITS COMPOUNDS

Q.1. Ethane, with the molecular formula C2H6 has :

(a) 6 covalent bond (b) 7 covalent bonds

(c) 8 covalent bonds (d) 7 covalent bonds

Q.2. Which of the following hydrocarbons undergo addition reactions :

C2H6, C3H8, C3H6, C2H2 and CH4

Q.3. How would you bring about the following conversions ?

(a) Ethane to Ethene

(b) Propanol to Propanoic acid

Q.4. Give chemical test to distinguish between saturated and unsaturated

hydrocarbons.

Q.5. An organic compound ‘A’ is a constituent of wine and is also used as a fuel in

spirit lamp. Compound ‘A’ on heating with alkaline potassium permanganate

gives another compound ‘B’ which turns blue litmus to red. Compound ‘A’ and ‘B”

combine in the presence of Conc. H2SO4 to give a sweet smelling compound ‘C’.

Identify compound ‘A’, ‘B’ and ‘C’ Also write the equations involved in the reaction.

Q.6. Why is CNG considered environmental friendly fuel ?

Q.7. Justify acidic nature of Ethanol with the help of a equation.

Q.8. A compound ‘A” has molecular formula C3H8O and react with Na-metal to evolve

H2 gas. Identify the compound and write all possible isomers of the compound.

Q.9. Explain the following terms :

(a) Esterification (ii) Saponifcation (iii) Decarboxylation

Q.10. Give reasons for the following observations :

(a) Air holes of a gas burner have to be adjusted/cleaned when the vessels kept on

flame get blackened by it.

(b) Use of synthetic detergents cause pollution of water.

Q.11. (i) Draw the electron dot structure or

(a) Propanal (b) Propyne

(ii) How would you name the following compounds :

(a) CH3 — CH2 — CH2 — CH2 — Cl

O II

(b) CH3 — CH2 — C — CH3

O II(c) H — C — H

CHAPTER 5

PERODIC CLASSIFICATION OF ELEMENTS

Q.1. Name two elements you would expect to show chemical reactions similar to

Magnesium. What is the basis of your choice ?

Q.2. Atomic number is considered to be more appropriate parameter than atomic mass

for classification of elements in a period table. Why ?

Q.3. (a) How do you calculate the valency of an element from its electronic

configuration ?

(b) What is the valency of Mg with atomic no. 12 and sulpher with atomic no. 16 ?

(c) How does valency vary across the period and down the group in modern pd.

table.

Q.4. Explain why sodium is more reactive than lithium ?

Q.5.Choose the following from modern periodic table:

(a) the most electropositive element .

(b the most electronegative element.

(c) the element with smallest atomic size.

(d) the element which is a metalloid.

(e) the element which shows maximum valency.

Q.6. A metal M forms an oxide having the formula M2O3 It belongs to third period in the

modern periodic table. Write the atomic number and valency of the metal.

Q.7. Suppose the elements of the triad proposed by Dobereiner are P, Q and R. If the

atomic mass of P is 6.9 and that of R is 39. Find the atomic mass of Q.

Q.8. If an element X is placed in group 14, what will be formula and nature of bonding

of its chloride ?

Q.9. Is it possible to have an element with atomic number 2.5 ?

Q.10. Compare the radii of two species X and Y. Give reasons for your answer :

(a) X has 12 protons and 12 electrons

(b) Y has 12 protons and 10 electrons