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Surface Tension Experiment (Capillary Rise Method)

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Surface Tension Experiment (Class 11)

 

Aim:

 

To find the surface tension of water by capillary rise.

 

Apparatus:

 

A narrow capillary tube of uniform bore of known radius, beaker containing water, travelling microscope, etc.

 

Principle:

 

Surface Tension, T = (1/2) x rhρg

where, h - capillary rise

r – radius of the bore

ρ – density of water

g – acceleration due to gravity

 

Procedure (Method 1):

A capillary tube is cleaned first with an acid, then with an alkali and finally with water. It is then passed through a hole in a cork and is arranged vertically with its lower end dipping in water contained in a beaker. A long pointer is passed through the same cork and fixed vertically so that its tip just touches the surface of water in the beaker. The water rises in the capillary tube. Least count of the vernier of the travelling microscope is noted. The microscope is kept horizontally and focussed on water level in the tube. Adjust the microscope till the horizontal crosswire just touches the lower meniscus. The total reading (R1) of the vernier is found out. The beaker containing water is carefully removed and the microscope alone is lowered till the horizontal cross-wire just touches the image of the tip of the pointer. The reading (R2) of the vernier is taken. The capillary rise, h = R1 — R2, of water in the tube is calculated, Surface tension (T) of water is calculated by the equation,

T = (1/2) x rhρg;

where r is the radius of the capillary tube and ρ is the density of water.

 

Procedure (Method 2):


A clean capillary tube is passed through a cork and is arranged vertically on a stand. Its lower end is arranged to be dipped in water taken in a beaker. A pointer is also passed through the same cork and its tip is made to touch the liquid surface. Due to capillarity water rises in the tube. The least count of the given travelling microscope is noted. The microscope is then focussed at the meniscus of the liquid in the capillary tube and the horizontal cross wire is made tangential to the meniscus. The microscope reading (MSR and VSR) is taken on the vertical scale. Total reading = M.S.R. + (V.S.R. x L.C.) is calculated. The beaker containing the liquid is carefully removed. The microscope is then focussed at the tip of the pointer and the microscope reading on the main scale and vernier scale are also noted. The difference between the two readings gives the capillary rise (h). The experiment is repeated by lowering the capillary tube to different depths in the beaker and the mean rise ‘h’ is determined. Knowing the values of r, ρ and g; surface tension (T) can be calculated.

 

Observations and Readings

 

To find capillary rise h


Least count of the vernier = ____ cm


Trial

Reading of meniscus

Reading of tip of pointer

Height, h=R1–R2

MSR

VSR

Total R1

MSR

VSR

Total R2

1

 

 

 

 

 

 

 

2

 

 

 

 

 

 

 

 

Mean height, h = _____m

Radius of the capillary tube = r = _____m

Density of water = ρ = 1000 kgm-3

Surface Tension of water, T = (1/2)rhρg = _____Nm-1


Result:


Surface tension of water =  ____

Potentiometer Experiment

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Potentiometer Experiment with Readings (Class 12)


POTENTIOMETER EXPERIMENT - 1


Aim:


To compare the e.m.fs of two primary cells (Daniel and Leclanche cells).


Apparatus:


Potentiometer, Accumulator (E), The given primary cells (E1 and E2), Rheostat (Rh), Key (K), Two way key (K1), Connecting wires etc.


Principle:


When a steady current flows through the potentiometer wire, the e m.f of the cell in the secondary circuit is proportional to its balancing length.


Let E1 and E2 be the e.m.fs of a Daniel cell and a Leclanche cell and l1 and l2 be their balancing lengths respectively, then


E1 l1 and

E2 l2

Therefore, E1/E2 = l1/l2


Procedure


The terminals A and B of the potentiometer are connected to an accumulator (E) through a rheostat (Rh) and a key (K). This forms the primary circuit. The positive terminal of the accumulator is connected to A. The Leclanche cell (E1) and the Daniel cell (E2) are included in the circuit using a two way key (K1) along with a galvanometer (G) and a high resistance (HR) through a jockey (J). This forms the secondary circuit.


The primary circuit is closed and the rheostat is adjusted for a suitable current. The Leclanche cell (E1) is included in the circuit. The jockey is pressed at the ends of the potentiometer wire (A and B). If the deflections obtained at the two ends are in opposite directions connections are correct. The jockey (J) is moved along the wire from A to B till the galvanometer shows zero deflection. The high resistance (HR) is then cut off and the exact balancing point is determined. The balancing length (l1) of the wire (distance from A to the jockey) is measured. The Daniel cell (E2) is then included in the circuit and the balancing length l2 is measured. The ratio E1/E2 = l1/l2 is calculated. The experiment is repeated by adjusting the rheostat (Rh) for different currents and the mean value of E1/E2 is determined.


Circuit Diagram

Observations and Readings


Trial

Balance length

E1/E2

Cell of emf E1, l1 cm

Cell of emf E2, l2 cm

1

150

374

0.40

2

141

364

0.38

3

139

365

0.38

4

190

392

0.48

5

177

399

0.44

 

Mean, E1/E2 = 0.416


Result:


The ratio of e.m.f’s = 0.416

 

POTENTIOMETER EXPERIMENT - 2


Aim:


To determine the resistance of the given cell using a potentiometer


Apparatus:


A potentiometer, accumulator (storage cell), the given cell (ex: Daniel or Leclanche cell), resistance box, keys, galvanometer, high resistance etc.


Theory:


When the key K is open, E l  ------------- (i)

When the key K is closed, ER/(R+r) 1’ ------------(ii)

Solving equation (i) and (ii), we get the internal resistance, r = R(l — l’)/l’

 

Procedure:


Connections are done as shown in the figure. The storage cell, the rheostat and a key are connected in series between the terminals A and B of the potentiometer wire. The positive terminal of the cell should be connected to A. The given cell, the galvanometer and a high resistance (HR) are connected in series between the terminal A and the jockey J of the potentiometer. See that the positive terminal of the battery is connected to the terminal A. A resistance box R is connected in parallel to the cell through a key K.


The primary circuit is closed. The key K is opened and the balancing length l is determined. (The rheostat is adjusted to get l as large as possible. Thereafter the rheostat should be adjusted).


The key K is closed. A suitable resistance R, say 5Ω, is taken from R. The balancing length I’ is determined. The internal resistance r of the cell is calculated using the relation,


r = R(l – l’)/l’ 


The experiment is repeated for different values of R in closed circuit. In each case, the internal resistance r of the cell is calculated. [The balancing  length l with R in open circuit need to be determined only at the beginning and at the end of the experiment. The average value l is taken].


Circuit Diagram


Observations and Readings


Balancing length with R in open circuit (l)

(1) 373 cm

(2) 369 cm

Mean l = 371 cm


Balancing length with R in closed circuit (l’)


Trial

R(Ω)

Balancing length, l’ cm

r = R(l – l’)/l’

1

1

81

3.58

2

2

134

3.53

3

3

152

4.32

4

4

163

5.10

5

5

207

3.96

 

Mean r = 4.098

 

Result:


Internal resistance of the cell is determined for different values of the external R.

 

Viva Questions and Answers


1. What is a cell?


A cell is a device by which electric energy is generated due to chemical action taking place inside it.


2. Define primary cell.


Primary cell is a cell in which gives electrical energy from chemical energy. This cell cannot be recharged.

Eg: Dry cell, Daniel cell, Leclanche cell


3. Define secondary cell.


Cell which stores electrical energy as chemical energy and returns it back as electrical energy, is called a secondary cell. This cell can be recharged.

Eg: Lead (acid) accumulator


4. Why is potentiometer called so?


Potentiometer works on the principle that for a constant current, fall of potential along a uniform wire is directly proportional to its length.


5. Define e.m.f. of a cell.


e.m.f. of a cell is defined as the p.d between the terminals of the cell when the cell is in an open circuit.


6. Why we prefer potentiometer rather than a voltmeter to measure e.m.f. of a cell?


Potentiometer method is a null deflection method. It does not draw any current from the source whose e.m.f. is to be measured. A voltmeter always draws some current.


7. The e.m.f. of the cell used in the primary circuit of the potentiometer should be more than the potential difference to be measured. Why?


If it is not so, the balance point will not attain on the potentiometer wire.


8 What is the principle of a potentiometer?


For a constant current, the potential drop across a wire is directly proportional to its length.


9. Which materials are suitable for potentiometer wire?


Manganin, constantan


10. What do you mean by sensitivity of a potentiometer?


Sensitivity of a potentiometer is the smallest potential difference that it can measure.

 

AC Sonometer Experiment with Readings (Class 12)

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FREQUENCY OF AC MAINS EXPERIMENT WITH READINGS (CLASS 12)

Aim:

 

To determine the frequency of ac main using a sonometer.

 

Apparatus:

 

Sonometer, a step down transformer (230 V – 6 V or 230 V – 9 V), horse-shoe magnet (or two powerful bar magnets), weight hanger, slotted weights, screw gauge, rheostat etc.

 

Principle:

 

If l is the length of the sonometer wire vibrating in resonance with the frequency n of the ac main, then,

Where M is the mass suspended at the end of the sonometer wire and mis the linear density of the sonometer wire.

 

Procedure:

 

The low voltage side (secondary) of the transformer is connected, through a rheostat R, across the sonometer wire. The bridge C is now placed closer to the bridge B. A horse-shoe magnet is mounted mid-way between B and C with the poles of the magnet on either side of the sonometer wire so as to produce a magnetic field perpendicular to the wire. (Instead of a horse shoe magnet, two powerful bar magnets can be clamped on either side of the sonometer wire with unlike poles facing each other). The wire can vibrate freely without touching the poles. The rheostat may be adjusted to reduce the current through the wire in order to prevent overheating.

 

A suitable mass M (say 20 g) is suspended from the free end of the sonometer wire. A light paper rider is placed on the wire between the bridges C and B. The primary of the transformer is connected to the ac main and the main supply is switched on. Since the current flows through the wire perpendicular to the magnetic field, the wire experiences a force. Since the current is alternating, the wire vibrates. The movable bridge C is adjusted until the vibrations of the wire BC show a maximum amplitude, indicating that resonance has been obtained. Now the paper rider will be thrown off. (The magnet is moved as the bridge is moved so that it is at the mid-way between the bridges B and C). The resonating length l of the wire between the bridges B and C is measured. Then (M/l2) is calculated. The experiment is repeated for different values of the load M and the average value of (M/ l2) is determined.

 

The radius r of the wire is measured by a screw gauge. The linear density in of the wire is calculated by the equation, m = πr2d; where d is the density of the material of the wire. The frequency n of the ac main is calculated using the equation,

Observations and Readings


Trial

Tension

Resonating length

Frequency (n)

1 (cm)

2 (cm)

Mean (l)

1

14.7

52.9

47.2

50.05

100

2

19.6

50.5

48

49.25

105

3

24.5

55.5

51.3

55.5

97

 

n = 100.66

Frequency = n/2 = 50.33 Hz


Calculations


Weight Suspended, T = 1.5 kg, 2 kg, 2.5 kg

Length of Sonometer wire = 1 m

Mass of wire, m = 1.5 x 10-4 kg

M = m/l = 1.5 x 10-4 kg/m

 

Result:

 

The frequency of the ac main = 50.33 Hz.

Metre Bridge Experiment with Readings (Class 12)

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Metre Bridge Experiment with Readings (Class 12) 


METRE BRIDGE EXPERIMENT - I


Aim: 


To find the resistance and hence determine the resistivity of the material of the wire.


Apparatus: 


Metre bridge, Battery (E), Key (K), Resistance box (R), Given resistance wire (X), High resistance (HR), Galvanometer (G), Jockey (J), Screw gauge etc.


Principle: 


The resistance of the given wire X = R[l/(100-l)]

where, R - Known resistance (Resistance put in the resistance box).

l - Balancing length from the side of X.

The resistivity of the material of the wire, ρ=  Xπr2/L

where, r - Radius of the given wire

X - Resistance of the given wire

L - Length of the given wire

Friction Experiment Viva Questions

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Coefficient of Friction Experiment Viva Questions and Answers


1. What is meant by friction?


Friction is an opposing force that comes into effect when a body moves or even tries to moves over another body’s surface.


2. Name the different types of friction.


(i). Static friction, (ii) limiting friction and (iii) kinetic friction

Frequency of AC Mains using Sonometer Viva Questions

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Frequency of AC Mains using Sonometer Experiment Viva Questions with Answers


1 Which is more dangerous in use a.c. or d.c.? Why?


Ans: For example, a 220V a.c has a peak value of 220 x 2 = 311 V whereas the peak value of a 220 d.c. is 220 V itself. Hence a.c. is more dangerous than d.c. of the same voltage.

Newton's Law of Cooling Viva Questions

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Viva Questions on Newton's Law of Cooling Experiment


1. What is meant by internal energy?


Ans: The sum of kinetic and potential energies of a body is called its internal energy.


2. Define temperature.


Ans: Temperature of a body is called as the degree of coldness or hotness of the body.


3. State Newton's law of cooling


Ans: The Newton's law of cooling is defined as the rate of decrease in heat from a body is directly proportional to the mean temperature difference between the body and its surroundings.


4. What is meant by thermodynamics?


Ans: Thermodynamics is a branch of science which deals with the study of transformation of heat energy into mechanical energy and vice-versa.


5. What is absolute zero of temperature?


Ans: —273.15° C


6. What is the tripple point temperature of water?


Ans: 273.16° K or 0.01°C


7. Define isothermal process.


Ans: Isothermal process is a physical change in which pressure and volume of a system change at constant temperature (It is a slow process).


8. Define adiabatic process.


Ans: Adiabatic process is a physical change in which pressure, volume and temperature change (It is a sudden process).


9. What is meant by irreversible process?


Ans: Any process that can't be retraced in the reverse order and in the opposite sense is called an irreversible process.


10. What is meant by reversible process?


Ans: A reversible process which can be made to proceed in two opposite directions with the same case, so that the system and the surroundings pass through exactly the same intermediate state as in the direct process.


11. Name the different modes of transmission of heat.


Ans: There are three modes of transmission of heat. They are conduction, radiation and convection.


12. What is radiation?


Ans: Radiation is energy or particles that origins from a source and travels through space or other medium. It may be able to go through various materials.


eg: Light, X-ray, Sound, Microwaves and so on


13. What is Stefan-Boltzmann law?


Ans: Stefan-Boltzmann law states that the total radiant heat power emitted from a surface is directly proportional to the fourth power of the black body’s absolute temperature.


ie, j* = σT4


14. Define emissivity (or relative emittance) of a surface.


Ans: Emissivity (ε) is defined as the relative ability of a surface to emit heat by radiation. It is the ratio of radiant energy from an object’s surface at given temperature to the radiant energy of a black body at same temperature.


15. State Kirchhoff's law.


Ans: Kirchhoff's law of radiation states that at thermal equilibrium, the power radiated by an object is equal to the power absorbed by that object.


16. What is the velocity of heat radiation?


Ans: Thermal radiation or Heat radiation is the energy transfer in the form of electromagnetic waves. The velocity of thermal radiation in the vacuum is same as that of light.

c0 = n0c

where, c0 = thermal radiation velocity

n0 = refractive index of medium

c = wave velocity


17. To which part of the electromagnetic spectrum do the thermal radiation belong?


Ans: Infrared region


18. What is a black body?


Ans: A black body is a surface that absorbs all radiant energy falls on it, regardless of frequency or angle of incidence.


19. What is meant by black body radiation?


Ans: Blackbody radiation is defined as the spectrum of light emitted by any heated object. It is the radiation emitted by the black body. For example, filament of a light bulb


20. What is Wien's displacement law?


Ans: The wavelength at which the maximum radiated power for a blackbody is inversely proportional to the absolute temperature.

ie, λmax = b/T

b = constant of proportionality

T = absolute temperature


21. Aim of Newton’s law of Cooling


Ans: To study the connection of temperature of a body to the time as it cools by radiating heat.


22. Apparatus of Newton’s law of Cooling


Ans: Calorimeter and stirrer, thermometer, clamp and stand, stop-watch, hot water and so on


23. Principle of Newton’s law of Cooling


Ans: By Newton's law of cooling, rate of cooling is directly proportional to mean temperature difference between the cooling substance (water) and the surrounding.

i.e., dθ/dt (θ-θ0)

where, θ - mean temperature of the cooling substance (water)

θ0 - temperature of the surrounding

As time increases, θ decreases, (θ-θ0) decreases and hence rate of fall of temperature dθ/dt also decreases.


24. Procedure of Newton’s law of Cooling


Ans: About 2/3 rd of the calorimeter is filled with hot water of about 110°C. A thermometer is suspended inside the calorimeter from a clamp and stand. Let θ0 be the temperature of the surrounding. Water is stirred continuously to make it cool uniformly. When the temperature of hot water falls to 100°C, a stop-watch is started. For every one minute the temperature is noted. The time-temperature observation is continued till the temperature falls to say 20°C.

A graph is plotted with time along the X-axis and temperature θ along the Y-axis, The graph is known as cooling-curve of the liquid.

Young's Modulus Experiment Viva Questions

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Viva Questions on Young's Modulus Experiment

 

1. What is meant by stress?


Ans: Stress is defined as the restoring force that is acting per unit area of a body.


2. What is meant by strain?


Ans: Strain is defined as the ratio of change in dimension to the original dimension.


3. What is the unit of stress?


Ans: Nm-2


4. What is the unit of strain?


Ans: No unit.


5. Define elasticity.


Ans: The property of a body to recover its original pattern when the deforming forces are removed is called elasticity.


6. Who was the first man to investigate the stretching of metals?


Ans: Robert Hooke


7. State Hooke's law.


Ans: Within the elastic limit, the stress grown is directly proportional to the strain created in a body.


8. Which is more elastic either steel wire or rubber wire of same diameters and lengths?


Ans: Steel wire


9. What is meant by Young's Modulus of elasticity?


Ans: The ratio between the normal stress to the longitudinal strain in elastic limit is called as Young's modulus of elasticity.


10. What is the unit of elastic limit?


Ans: Nm-2


11. Distinguish between stress and pressure.


Ans: The restoring force acting per unit area is Stress and the amount of force applied per unit area is Pressure.


12. What is meant by elastic limit?


Ans: The maximum stress for a body can withstand before the permanent deformation of size or shape.


13. What is the modulus of elasticity?


Ans: The relationship (ratio) between stress and strain is called as Modulus of Elasticity (Young's modulus of elasticity).

λ = stress/strain


14. What are the different moduli of elasticity?


Ans: (i) Young's modulus,

(ii) Shear modulus, and

(iii) Bulk modulus.


15. What is the unit of modulus of elasticity?


Ans: Nm-2 or Pa


16. Why do you use a micrometer or vernier instead of a metre scale to measure the increase in length of the wire?


Ans: It is because the vernier can slide freely against the main scale.


17. What is elastic hysteresis?


Ans: Elastic Hysteresis is the difference between the strain energy and stress energy. It is the lagging of strain behind the stress.


18. Aim of Young's Modulus Experiment


Ans: To find out the Young's modulus of the material for a given wire by Searle's apparatus.


19. Apparatus of Young's Modulus Experiment


Ans: The Searl's apparatus, weight hanger, slotted weights, screw gauge, metre rule etc. The Searl's apparatus consists of two long metal wires AB and CD each of length about 2 m suspended side by side from a rigid support. AB is the experimental wire whose Young's modulus is to be determined. CD is the observation wire. The experimental wire AB carries a vernier V and the observation wire CD carries a main scale S. The vernier can slide freely against the main scale. The observation wire is made taut by suspending a load W at the lower end of the main scale.


20. Procedure of Young's Modulus Experiment

Ans: The experimental wire is made taut by placing a suitable dead load Wo on the weight hanger attached to the lower end of the vernier. It is brought into elastic mood by repeatedly loading, and unloading.


With the dead weight W0 alone, the reading r0 of the vernier is taken. A suitable weight m, say 0.5 kg, is placed on the weight hanger over the dead load and the reading of the vernier is again taken. The experiment is repeated by adding load 2 m, 3 m, 4 m... over the dead load and the vernier is read in each case. The load are removed one by one and the vernier readings are again taken. The average readings r1, r2, r3, r4,... for the load (W0 + m), (W0 +2m) , (W0 +3m)(W0 +4m)…... are calculated. From these readings extensions for the loads M = m, 2m, 3m, 4m, …. are taken as (r1 — r0), (r2 — r0), (r3 — r0), (r4 — r0),….  A graph is drawn with extension along the Y-axis and load along the X-axis. The graph is a straight line. The reciprocal of its slope gives M/l, the load/extension of the wire.


The length L of the experimental were from the support to the point of attachment to the vernier is measured by a metre rule. The radius r of this wire is measured with a screw gauge. The Young's modulus of the material of the wire AB is calculated by the equation. Y = MgL/πr2l = Lg/πr2 x (M/l)

Atoms and Molecules Viva Questions

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ATOMS AND MOLECULES VIVA QUESTIONS (CLASS 9)

1. What is the Avogadro number of Helium (He) atoms weigh ?


Ans: 4.0 g


2. Determine the number of hydrogen atoms in 3 mole of NH3 ?


Ans: 9 x 6.02 x 1023


3. Which of the following weighs least among  the following?

(a) 0.224 litres of O2 at NTP

(b) 6.02 x 1023 molecules of oxygen

(c) 6.02 x 1023 atoms of carbon

(d) 10 g of CO2


Ans: 0.224 litres of O2 at NTP


4. An element's oxides contain 57.1 % and 72.1 % oxygen, respectively. What is the second oxide if the first oxide is MO?


Ans: MO2


5. What is the molarity of Na2CO3 solution containing 10.6 g per 500 ml solution?


Ans:  0.2


6. Determine the volume of 0.5 M HNO3 that can be prepared from 25 mL of 2.5 M HNO3


Ans: 125 mL


7. If 30 L is converted into SI unit and expressed in scientific notation,  determine the value obtained?


Ans:  3 x 10-2 m3


8. The average density of earth is 5.5 g cm-3. In kg m-3, determine the average density?


Ans: 5.5 x 10-3


9.  In 1.0046, how many significant figures are there?


Ans:  five


10. From the given lists, which of the following has more number of rnolecules ?

(a) 1 g CO2

(b) 1 g N2

(c) 1 g H2

(d) 1 g CH4


Ans: 1 g H2


11. Carbon monoxide and carbon dioxide may be taken as examples for illustrating which  law ?


Ans: Law of multiple proportions


12. From the given, which of the following contains Avogadro number of atoms,

(a) 11.2 L of H2 at STP

(b) 32 g of oxygen

(c) 28 g nitrogen

(d) 22.4 L of Cl2 at STP


Ans: 11.2 L of H2 at STP


13. Find the volume of oxygen at STP required to react with 3 g graphite to give CO2  ?


Ans: 5.6 L


14. A solute has a molecular mass of 60 g and 90 g of it is dissolved in a litre of solution. Then what is its molarity?


Ans: 1.5


15. From the given samples, determine which of the following is not a mixture?

(a) air (b) milk (c) smoke (d) water


Ans: Water


16. The volume of l g of a gas at STP is 1.12 L. What will be its molecular mass ?


Ans: 20


17. A mass of 16 g of an element was mixed with 32 g oxygen when 32 g of compound was formed. If the element was the limiting reagent, what will be the mass ratio of the element to oxygen in the compound ?


Ans:  1:1


18. Chemical equations are balanced so that they are in accordance with which law?


Ans: Law of conservation of mass


19. At NTP, 0.225 g of carbon reacts with 140 mL of oxygen. What would the compound's molecular formula be then?


Ans: C3O2


20. 0.25 g of a tetratomic element is 3.125 x 10-3 mole. Then what is the atomic mass of the element is


Ans:  20


21. Neon contains two isotopes of atomic masses 20 and 22 in the mass ratio 9 : 1  respectively. Find the atomic mass of the element ?


Ans: 20.2


22. What is the atomicity of ozone?


Ans: The atomicity of ozone is 2


23. Determine which molecule from the following elements is tetratomic?

(a) ozone (b) phosphorus (c) sulphur (d) xenon


Ans: Phosphorus


24. What is the number of significant figures in 6.023 x 1023 ?


Ans: The number of significant figures is  4  


25. Determine the approximate number of atoms present in lg CH3COOH ?


Ans:  The approximate number of atoms present is 1022


26. Find the number of significant figures in 0.0480 ?


Ans: The number of significant figures is 3


27. Give the number of dimensionally independent physical quantities in SI units?


Ans: 7


28. Give the equivalent of 1 cm3 of volume?


Ans: 10-3 dm3


29. Determine the equivalent of one joule of energy ?


Ans:  0.2381 cal


30. From the following, determine the SI unit of work?

(a) cal (b) Joule (c) litre-atm (d) ergs


Ans: Joule

 

31. One kg weight is equivalent to


Ans:  9.8 N


32. The unit of J. Pa-I is equivalent to


Ans:  m3


33.  From the listed elements, determine which of the element is not an element?

(a) Diamond (b) 22 carat gold (c) graphite (d) oxygen


Ans: 22 carat gold


34.  From the given mixtures, find which one is not a homogeneous mixture?

(a) one rupee coin (b) gasoline (c) iodised table salt (d) air


Ans: Iodised table salt


35.  Give the mass of a Mg atom ?


Ans: The mass of Mg atom is 24.3/6.02 x 1023 g  


36.  Determine the number of mols of carbon present in 1 mot of ethanol?


Ans:  2


37. 615.00 has...........significant figures


Ans: 5


38. How will you measure the Luminous intensity ?


Ans: The luminous intensity is measured in terms of Candela


39. The prefix tera means


Ans: 1012


40. Pure water can be obtained from sea water by which process?


Ans:  Distillation process


41. From the listed elements, find which one contains the largest number of molecules?

(a) 1g CO2  (b) 1g N2 (c) 1 g H2  (d) 1 g CH4    


Ans:  1 g H2   


42. Carbon forms two oxides CO and CO2. This illustrates which law?


Ans: Law of  Multiple proportions


43. Two oxides of a metal contain 50% and 60% of oxygen respectively. If the formula of the first oxide is MO, determine the formula of the second one?


Ans: The formula of the second one is M2O3


44. What is the simplest formula for a compound with 50% of element X (atomic mass 10) and 50% of element Y (atomic mass 20) in it?


Ans: The simplest formula is: X2Y


45. Which of the following contains the same number of atoms as in 6 g carbon?

(a) 24 g Mg  (b) 23 g Sodium  (c) 20 g Ca  (d) 63.5 g Cu


Ans: 20 g Ca 


46. 3.2 g of gas contains 6.02 x 1022 molecules. determine its vapour density?


Ans: The vapour density is 16


47. Find the volume of 1 M NaOH required to convert 1.2 g of NaHSO4 completely to Na2SO4 ?


Ans: 10 ml


48. How many moles of water would be formed when 4 g of methane (CH4) are burnt?


Ans: 0.5


49. calculate the number of significant figures of the following numbers?

(a) 100.04   

Ans: 5


(b) 4.20 x 1010 

Ans: 3


(c) 324.0

Ans: 4


(d) 500.00

Ans: 5


(e) 0.02670 

Ans: 4


50. Compute the following:

(a) 5.28 x 0.156 x 3/0.428

Ans: 5.77


(b) 5.28 x 0.156 x 3/0.421

Ans: 5.67


51.  List the proper number of significant figures in the following and indicate which zeros are significant?

(a) 0.216

Ans: 3 Significant figures


(b) 90.1

Ans: 3 Significant figures and zero is significant


(c) 800.0

Ans: 4 Significant figures all zeros are significant


(d) 0.0670

Ans: 3 Significant figures, last zero is significant


52.  Determine the number of moles of Oxygen atoms are there in

(a) one mole of HNO3

Ans: 3 moles


(b) one mole of H2SO4

Ans: 4 moles


53. Determine the number of moles of water produced when 8 g of methane (CH4) are burnt?


Ans: 1 mol.


54. How many moles of KClO3 are needed to give 1.5 moles of oxygen?


Ans: 1 mol.


55. How many moles of KCl are formed when 0.33 mol of KClO3 is decomposed?


Ans: 0.33 mol.


56. A chemist weighs 10 g of water, 10 g of ammonia and 10 g of hydrogen chloride. Calculate the total number of moles contained in the mixture?


Ans: 1.4 moles


57. Give the mass of a silver atom?


Ans: 1.794 x 10-22


58. Determine the number of molecules contained in a drop of water weighing 0.04 g?


Ans: 1.34 x 1021 molecules


59. Express 0.000000367 in scientific notation and calculate the significant figures?


Ans: 3.67 x 10-7 ; Number of significant figures is 3


60. What is the mass of HCl required to neutralise completely 5g  of NaOH?


Ans: 4.545 g


61. Which contains more molecules: 1 g of sulphur dioxide or 1 g of sulphur trioxide?


Ans: 1 g of SO2