Is burnt wood a chemical change?

Answer 1

it is a chemical change

Yes. Wood is composed of a number of complex chemical compounds, and cellulose is a principle one. Much of the material in wood is reduced to carbon dioxide and water, but there are a considerable number of combustion byproducts and also many products of incomplete combustion. But through burning, wood undergoes a chemical change to become ash and all the stuff that is carried away in the smoke stream. Heat, of course, is a byproduct. when the ashes are formed they can not be formed into a log or peice of wood
Yes, burning wood is a chemical change.

- A.Gibbs
Yes; the fire (combustion) is using oxygen in the air to release heat energy and carbon atoms in the wood. Wood is mostly made up of a gas called cellulose and the burning allows oxygen molecules to mix with the cellulose. This exerts various gases and the heating will obviously convert the wood to ash and scoot.
its chemical change
Yes, wood undergoes a chemical change when it is burned. For the most part it is a redox reaction.
Yes

Answer 2

Burning wood is a chemical change because new substances, principally carbon dioxide and water, are produced.
Because when the wood burns, the wood and oxygen are converted into carbon dioxide and water. This kind of reaction is called combustion.
Because when the wood burns, the wood and oxygen are converted into carbon dioxide and water. This kind of reaction is called combustion.

Burning wood is a chemical change because burning is a chemical reaction: oxidation.
This is simply due to the fact that the molecules that make up the wood and oxygen are converted by a chemical reaction called combustion into carbon dioxide and water.
Because the volume ,mass ,color ,texture ,shape and the size of the wood has changed.
Cellulose, the primary component of wood, reacts with oxygen to produce carbon dioxide, carbon monoxide, and water vapor. The cellulose and O2 are gone, changes into new substances.

It is a chemical change because it burns and makes smoke which is steam..
Because it breaks down the elements and changes the shape and form but isnt exactly changed.
1. A bomber drops a bomb from an aircraft flying at 2000 km/hr. at an altitude of 7km. The speed at which the bomb will strike the earth would be

A) greater than 2000 km/hr. B) less than 2000 km/hr.

C) equal to 2000 km/hr. D)Can't be compared with the given data

2. The velocity of a body was noted to be constant during five minutes of its motion. What was its acceleration during this interval ?

A) 9.81 m/s2 B) -9.81 m/s2 C) 6.67 ´ 1011 m/s2 D) 0 m/s2

3. Which of the following is /are vector(s)

A) Force B) Velocity C) Weight D) All of the above

4. If V1 and V2 be two vectors at 900 from each other, having magnitudes of 10 and 20 units each, what will be the value of V1.V2 ?

A) Equal to 200 units B) Equal to 10 units C) Equal to 20 units D) Equal to 0

5. Four samples of different material having the same mass were noted to have the following volumes, 5cc, 10cc, 3cc and 19cc. Which of them is more dense?

A) The one having volume 5cc. B) The one having volume 10cc.

C) The one having volume 3cc. D) The one having volume 19cc.

6. The centripetal force of a body having mass m and rotating at a linear speed of v in a circle of radius r is given by

A) mv/r B) mvr C) mv2/r D) mv/r2

7. The unit of specific gravity in S.I. units is

A) g/cm3 B) kg/m3 C) g/litre D) kg/litre

8. Temperature of 1000C is equal to

A) 1000F B) 2120F C) 1120F D) 50F

9. Specific heat is defined as the amount of heat required to

A) raise the temperature of a body by 273o C

B) change the temperature of unit mass of a body through 1o C

C) change the state of unit mass of a body

D) change the temperature of unit mass of a body through 212o F

10. The volume of a gas

A) is always independent of pressure B) is proportional to temperature at constant pressure

C) is proportional to pressure at constant temperature D) both B) and C)

11. On heating, the viscosity of liquids generally

A) Decreases B) Increases C) Remains the same D) It depends upon the liquid

12. A chemical compound having only carbon and hydrogen is called:

A) Sulfuric acid B) hydrocarbon C) hydride D) All of above

13. Which of the following is/are Halogens

A) Chlorine B) Iodine C) Fluorine D) All of above

14. Atomic number of an atom is equal to the number of

A) Protons B) Electrons C) Neutrons D) Protons and Neutrons

15. Which of the following is closer to the value of standard atmospheric pressure:

A) 14.7 psi B) 760 mm Hg C) 101.3 k Pa D) All of the above

16. If pressure of the liquid is decreased, the boiling point will

A) Increase B) Decrease C) Remain the same

D) Increase or decrease depending upon some other parameters

17. Cane Sugar is mainly composed of

A) Sucrose B) Sodium chloride C) Iodine D) None of above

18. If a body falls freely under gravity, the gravitational acceleration will be equal to

A) 9.8 m/s2. B) -8.9 m/s2. C) -9.8 m/s2. D) None of above.

19. The temperature at which the volume of a gas theoretically becomes zero is called:

A) Absolute zero B) Zero Celsius C) Freezing point D) Boiling point

20. A vessel used for production of steam is called:

A) Turbine B) Boiler C) Condenser D) Steam ejector

21. (a + 2b)2 = ________________

A) a2 + b2 + 2ab B) a2 + 4b2 + 8ab C) a2 + 4b2 + 4ab D) a2 + b2 - 4ab

22. If A and B be two matrices such that A = and B = the "A-1 = B"

A) The statement is false because inverse of 3´2 matrix is not possible

B) The statement is false because A-1 has some other value than the given above.

C) The statement may be false or true depending upon the values of a,b and x,y

D) The statement is true

23. A swimmer can swim with an average speed of 9km/hr in still water. What would be his net speed if he is crossing a river flowing at 20 km/hr, trying to swim straight along the breadth of the river?

A) About 22 km/hr B) Exactly 20 km/hr C) About 18 km/hr D) Exactly 9km/hr

24. The unit of solid angle is

A) Solid angle B) Radian C) Seradian D) Candela

25. LPG stands for

A) Liquid petroleum gas B) Low pressure gas

C) Lubricated and purified gas D) Low performance gas

26. A moving coil galvanometer can be used as an ammeter by adding;

A) A series resistance with its coil B) A parallel resistance with its coil

C) A diode in series with its coil D) A diode in parallel with its coil

27. Thermal parameters can be measured by

A) RTD B) Thermocouple C) Bi-metallic strip D) All of above

28. The working of thermocouple is based upon the principle called

A) Seebeck effect B) Newton's Law C) Thomson effect D) Photoelectric effect

29. For a liquid flowing through a tube, Bernoulli's theorem at a point states that

A) sum of pressure energy, P.E. and K.E. are constant

B) sum of pressure energy, P.E. and K.E. are variable

C) P.E and K.E are constant only D)None of above

30. The range of temperature on Kelvin scale can be

A) -273° to 273° B) 0° to 373° C) -1000° to 273° D)- 100° to 100°

31. Vacuum can be measured with the help of a;

A) Pyrometer B) Strip meter D) Induction meter D) Bourden Gauge

32. Electromagnetic induction principle is employed in

A) Moving coil instrumentation B) Bourden tube

C) Aneroid barometer D) Flow venture

33. The arrangement of resistances (R1,R2,R3,R4) and a galvanometer (G) in figure is called,

A) Kirchoff's apparatus B) Wheatstone bridge

C) Wheatmarble bridge D) Voltammeter

34. A galvanometer can be converted into a voltmeter by placing

A) Shunt resistance with its coil B)Series resistance with its coil

C) voltage can directly be measured

D) voltage cannot be measured with the help of a galvanometer

35. A Geiger-Mueller tube is used for:

A) Flow rate measurement of gases B) Flow rate measurement of volatile liquids

C) Measurement of very high voltage D) Detection of ionizing radiation

36. If the flow rate is 2 m3/s then what will be the velocity of the liquid through the tube having diameter of 50 cm nearly

A) 10 m/s B) 15 m/s C) 3.6 m/s D)4 m/s

37. The linear speed of a body revolving at 1200 rpm in a circular path of 0.8 meter radius would be closed to

A) 400 m/s B) 300 m/s C) 200 m/s D) 100 m/s

38. Which of the following atoms contains least number of neutrons?

A) 92U235 B) 93Np240 C) 92U238 D) 93Np239

39. For what value of x is it true that ?

A) All values of x B) All values of x except

C) All values of x greater than D) All values of x less than

40. If y=3 Sinx then dy/dx =

A) 3 Sinx B) 3Cosx C) 0 D)3

41. A circle has its centre at (0,0). The line y = -2 is tangent to it. The radius of the circle is

A)1 B) 2 C) 5 D)6

42. The Ozone layer is useful for us because

A) It protects us from harmful radiation B) It provides fresh air

B) It absorbs Earth pollution D)Ozone layer is not useful for us

43 pH of a perfect neutral solution is

A) 0 B) 7 C) 9 D) 1

44. 125 cm3 of a gas is collected at 150°C and 755 mm of Hg. What is the volume of gas at STP?

A) 118 cm3 B) 135 cm3 C) 100 cm3 D) 10 cm3

45. Sum of the masses of constituent nucleons is greater than mass of a nucleus. The difference is due to

A) Energy level within nucleus B) Binding energy

C) Potential energy D) Ionization potential

46. The Voltage drop across a 500 Watt electric heater having resistance of 5 Ohm is

A) 50 Volt B) 250 Volt C) 2500 Volt D) 100 VolT

47. The speed of a synchronous motor with 60 Hz. power supply is

A) 100 rpm B) 600 rpm C) 3600 rpm D) 4000 rpm

48. g- rays

A) are positively charged particles B) are negatively charged particles

C) are neutral particles D) can have any charge

49. A nuclear bomb is more dangerous than an equivalent TNT bomb because

A) of more weight B) of radiation C) of bad smell D) both B and C

50. 6C11 and 5B11 are two

A) isotopes B) isobars C) isotones D) isomers

51. Mass can be converted to energy. Einstein gave a mathematical relation for this statement. How much energy can be obtained approximately from 1 micro-gram of mass according to that formula?

A) 1 micro-joule B) 900 joules C) 90000 joules D) 90 x 109 joules

52. Which of the following is/are NOT real number(s)?

A) 0 B) -p C) D) All of the above are real numbers

53. A quadratic equation has ALWAYS

A) real roots B) imaginary roots C) equal roots D) None of the above

54 Log5 124 is

A) greater than 0 and less than 1 B) greater than 1 and less than 2

C) greater than 2 and less than 3 D) greater than 3 and less than 4

55. The equation of a line with slope - 2 and passing through the point (2,3) is

A) x - y = 0 B) x + 4y = 16 C) 2y + 4x - 16 = 0 D) x + 2y +16 = 0

56. The probability to draw a QUEEN OR a KING from a deck of 52 cards is

A) 52 B) 13 C) 8 D) 2/13

57. How many possibilities are there to select a team of 3 members from 9 players?

A) 20 B) 34 C) 70 D) 84

58. A bus leaves a station at 5 O'clock with an average speed of 50 km/h. A car leaves the same station at 8 O'clock with an average speed of 80 km/h. At what time will the car catch the bus?

A) 11 O'clock B) 12 O'clock C) 1 O'clock D) 30 past 1 O'clock

59. Choose fourth member for the team of Jamal, Kamal, Latif

A) Akram B) Majid C) Aman D) Ali

60. Separate the odd member from "Iron, Gold, Carbon, Silver"

A) Iron B) Gold C) Carbon D) Silver

61. Complete the series 23, 32, 43, 56, 71, -----, -----

A) 100, 127 B) 98, 128 C) 88, 107 D) 92, 111

62. If X = A t + B t2 where X is in kilograms and t is in hours, the unit of B will be

A) kg2/hr B) kg/hr2 C) kg/hr D) kg

63. If A be a binary number then =______

A) A B) C) 0 D) 1

64. The area of a square is 40000 cm2. What will be length of diagonal?

A) meter B) 2 meter C) meter D) 200 meter

65. Base and perpendicular of a right-angl triangle are 1, 1, then hypotenuse is.

A) 1 B) 2 C) .5 D) 1.414

66. A quadrilateral having opposite sides parallel is called

A) Kite. B) Triangle. C) Parallelogram. D) Trapezoid.

67. Two angles of a triangle measure 600, 800, the measure of third angle is

A) 600 B) 800 C) 400 D) 200

68. In an isosceles triangle, two angles are

A) Complementary B) Supplementary C) Congruent D) Right angle

69. 1 + tan2θ =

A) Sin2θ B) Cos2θ C) Cot2θ D) Sec2θ

70. x + 2 = 9 is a ______________.

A) Linear equation. B) Radical equation C) Quadratic equation D) Cubic equation

71. A father is 35 years of age. 3 years ago, he was 4 times as old as his son. The age of the son at that time was

A) 4 years B) 8 years C) 10 years D) 6 years

72. Rabia purchased 2.5 meters Lattha & 4.5 meter Mulmal both at the rate of Rs.25 per meter. She had a total amount of Rs.300. What amount remained with her after paying for the cloth purchased?

A) 125 B) 130 C) 200 D) 225

73. A rectangular park is 170 m long & 130 m wide. A road 5 m wide has been constructed in the inner side of the boundary. Find the area of road.

A) 2900 m2 B) 22100 m2 C) 3000 m2 D) 2100 m2

74. One horse power is equivalent to

A) 647 watts B) 467 watts C) 746 watts D) None of the above

75. The gas used in refrigerator is usually

A) Hydrogen B) Oxygen C) Freon D) Sulphur dioxide

76. The relation between frequency (f) and time period (T) of a wave is

A) f = 2T B) f = 1/T C) f = T2 D) None of the above

77. 2+14 in Hexadecimal numbers is equal to

A) 16 B) 12 C) 10 D) A

78. The area of triangle formed by the lines y=5-x, y=1 and , x=0 is

A) 16 B) 8 C) 4 D) 2

79. Simplifying the expression [ AB+ABC+AB(CD+AD+AB.CD)] using Boolean algebra will give.

A) ABD B) AB(CD.AD) C) ABCD D) AB

80. The price of sugar was Rs. 25.00 on November 30, 2006. It got increased in December by 40%. In April the price was reduced by 40%. The new price will be

A) Rs. 25.00 /kg B) More than Rs. 25.00 /kg

C) Les than Rs. 25.00 /kg D) Can not be calculated from the given data

Answer 3

yes
Yes It Is, Wood Basically Is An Organic Combustion, When Burned Decompose In To CO2 & Carbon Mainly. Also CO And Other Oxides Are Produced.

All burnings are chemical reactions (oxidations).
Yes, burning wood is a chemical reaction.

Answer 4

No, cutting through wood is a physical change, because the chemical identity of the wood remains the same. It is still wood after you cut it.
No, it's a physical change. Chemically - it's still wood !

Answer 5

Yes Because you can not change back the burnt wood into its original place. In other words, you cant change the ashes of the log and glue them back together to make it the way it looked before.

Answer 6

The only way for ALL this energy to be released is for the kilogram of water to be totally annhilated. This process involves the complete destruction of matter, and occurs only when that matter meets an equal amount of antimatter ... a substance composed of mass with a negative charge. Antimatter does exist; it is observable as single subatomic particles in radioactive decay, and has been created in the laboratory. But it is rather short-lived (!), since it annihilates itself and an equal quantity of ordinary matter as soon as it encounters anything. For this reason, it has not yet been made in measurable quantities, so our kilogram of water can't be turned into energy by mixing it with 'antiwater'. At least, not yet.

Another phenomenon peculiar to small elementary particles like protons is that they combine. A single proton forms the nucleus of a hydrogen atom. Two protons are found in the nucleus of a helium atom. This is how the elements are formed ... all the way up to the heaviest naturally occuring substance, uranium, which has 92 protons in its nucleus.

It is possible to make two free protons (Hydrogen nuclei) come together to make the beginnings of a helium nucleus. This requires that the protons be hurled at each other at a very high speed. This process occurs in the sun, but can also be replicated on earth with lasers, magnets, or in the center of an atomic bomb. The process is called nuclear fusion.

What makes it interesting is that when the two protons are forced to combine, they don't need as much of their energy (or mass). Two protons stuck together have less mass than two single separate protons!

When the protons are forced together, this extra mass is released ... as energy! Typically this amounts to about 0.7% of the total mass, converted to an amount of energy predictable using the formula .

Elements heavier than iron are unstable. Some of them are very unstable! This means that their nuclei, composed of many positively charged protons, which want to repel from each other, are liable to fall apart at any moment! We call atoms like this radioactive.

Uranium, for example, is radioactive. Every second, many of the atoms in a chunk of uranium are falling apart. When this happens, the pieces, which are now new elements (with fewer protons) are LESS massive in total than the original uranium atoms. The extra mass disappears as energy ... again according to the formula ! This process is called nuclear fission.

Both these nuclear reactions release a small portion of the mass involved as energy. Large amounts of energy! You are probably more familiar with their uses. Nuclear fusion is what powers a modern nuclear warhead. Nuclear fission (less powerful) is what happens in an atomic bomb (like the ones used against Japan in WWII), or in a nuclear power plant.

Albert Einstein was able to see where an understanding of this formula would lead.

Answer 7

Burning wood releases carbon dioxide, other gases and fine particle pollution into the atmosphere. It is a chemical and a physical change, as the wood turns from solid wood to a powdery ash, and the gases trapped in the wood is released.

Answer 8

All burnings are chemical reactions (oxidations).

Answer 9

Yes

Answer 10

Yes, it is.