1214 + Interview Questions in Chemistry in Class 8 Page 2 InterviewSolution

51.	Though coke is made from coal, it is used for metallurgical processes instead of coal. Give reason.
Answer» Solution :Coal is fed into the coke oven and heated in an oxygen FREE atmosphere and devolatized. The heating is DONE in various steps which SUBJECT the coal to different temperatures for VARYING time periods. During each step different VOLATILE compounds are driven off. At the end of the heating process coke remains. It is porous with good strength. SInce coke is a purer form of carbon then coal and is porous, it is a better reducing agent then coal.

Discussion

52.	Valency of a carbonate (CO_(3)) radical is
Answer» 2 3 4 5 Answer :A

Discussion

53.	Write the reaction involved in the preparation of silicon carbide .
Answer» SOLUTION :`SiO_(2)+3C to Sic+2COuarr `

Discussion

54.	Which of the following is a pure substance?
Answer» Duralumin Magnalium Bell METAL Magnesium Answer :C::D

Discussion

55.	Two research scholars Rony and Jony, needed red phosphorus and White phosphorus respectively, for a research programme. Both of them went to a chemical store to purchase red phosphorus and white phosphorus.The store keeper gave a normal glass bottle containing red phosphorus and a glass bottle containing white phosphorus which was kept in water.Justify the above observations
Answer» SOLUTION : The ignition temperature of white phosphorus Oleum is very low as COMPARED to RED phosphorus.And hence it catches fire in the presence of air. So White phosphorous is PRESERVED under water as it s density is high. The phosphorus settles down.As a result it is not exposed to air.Whereas red phosphorus has a high ignition temperature and does not catch fire on exposure to air. So it is stored in normal glass bottles.

Discussion

56.	Thesolubility of CaSO_(4)
Answer» DECREASE with INCREASE in TEMPERATURE increase and then decrease with increase in temperature decrease and then increase with increase in temperature Answer :C

Discussion

57.	Why are diesel and petrol replaced by CNG as fuels in automobiles?
Answer» Answer :CNG or COMPRESSED Natural Gas is a cleaner fuel and it produces harmful PRODUCTS in lesser amount. So, DIESEL and petrol are replaced by CNG as fuels in AUTOMOBILES.

Discussion

58.	What are catalytic reactions? Give an example.
Answer» SOLUTION :PRESENCE of a CATALYST.

Discussion

59.	The valencies of sulphur in hydrogen sulphide and sulphur dioxide are___________ and __________ respectively.
Answer» ANSWER :2,4

Discussion

60.	Which postulate of Dalton's atomic theory is considered to be correct even now?
Answer» Solution :TINIEST particles of MATER that TAKE part in CHEMICAL reactions

Discussion

61.	Tincture of iodine is a mixture of ________and________.
Answer» ANSWER :IODINE and ALCOHOL

Discussion

62.	Water is sprayed in orange grooves in very cold countries during winter. Give reasons.
Answer» SOLUTION :(i) Physical change in water in very cold COUNTRIES. (ii) Heat changes during these changes. (III) Effect of corresponding heat on plants. (IV) Conduction of heat through ice.

Discussion

63.	What happens during rusting and .burning of magnesium ribbon?
Answer» ANSWER :During rusting and burning of MAGNESIUM ribbon, FORMATION of oxides TAKES place.

Discussion

64.	X+O_(2)toY,Y+H_(2)OtoZ,Z turns red litmus to blue then X may be
Answer» Ca S C P Answer :A

Discussion

65.	What is the maximum number of electrons that can be present in the nth shell of an atom?
Answer» SOLUTION :`2N^(2)`

Discussion

66.	The temperature of troposphere decrease with increase in altitude. Is the same true of stratosphere? Justify.
Answer» Solution :The layer of atmosphere which is CLOSE to earth's SURFACE is called troposphere. Hence the temperature of troposphere is inversely proportional to distance between surface of the earth and the different regions of troposphere. Hence temperature in this layer decreases with INCREASE in altitude. Interconversion of ozone and oxygen is more in the upper layer of stratosphere. During this process lot of HEAT energy is RELEASED and hence with increasing altitude temperature also increases in stratophere.

Discussion

67.	What is plastic? Write a short note on different categories ofplastic.
Answer» SOLUTION :(1) Definition of PLASTIC. (II) Thermoplastics. (III) THERMOSETS

Discussion

68.	What is acrylic? Why are they widely used?
Answer» Answer :Acrylic is a typeof SYNTHETIC fibre which resembles NATURAL WOOL. These are used in MAKING sweaters.

Discussion

69.	what is coke?
Answer» Answer :Coke is a by-product of COAL. It is a TOUGH, POROUS and black SUBSTANCE and an ALMOST pure form of carbon

Discussion

70.	Which of the following is false regarding epoxy resin?
Answer» It is a thermosetting polymer It is less brittle in NATURE It has relatively weak bands. It has cross linking AMONG polymeric chains Solution :CHOICE(4)

Discussion

71.	Write the steps in naming a binary compound formed by two non-metallic ekmcnts, except hydrogen, with the help of an example .
Answer» Solution :(i) Less electronegative NONMETAL follm-ved by more dectronegative NON metal. (ii) Prefix is added co more ELECTRONEGA tive ELEMENT

Discussion

72.	Which of the following elements is used for vulcanization?
Answer» PHOSPHORUS SULPHUR Oxygen Nitrogen Solution :Sulphur is USED for VULCANISATION.

Discussion

73.	What is chemical decomposition? Give one example.
Answer» SOLUTION :SPLITTING of a COMPOUND

Discussion

74.	Though the dust particles cause air pollution, the presence of dust particles help in sustenance of life. Explain.
Answer» SOLUTION :(i) Role of DUST particales in FORMATION of cloud. (ii) Role of cloud formation in WATER cycle. (iii) Role of water cycle in sustenace of life.

Discussion

75.	Which of the following are used in air conditioning and refrigeration systems?
Answer» CO `CO_(2)` `CFCS` `O_(3)` ANSWER :C

Discussion

76.	What is the advantage of liquid CO_(2) fire extinguisher over soda-acid fire extinguisher? Explain.
Answer» Solution :(i) Comparison of the working principle of the given fire extinguisher . (ii) Comparison of composition of the MATERIALS used in soda fire extinguisher with that used in liquid `CO_(2)` fire extinguisher. (iii) TRANSFORMATION that takes place during the usage of both the fire EXTINGUISHERS. (iv) Comparison of physical properties of the products formed. (V) Types of fire where soda-acid fire extinguisher cannot be used.

Discussion

77.	What are the physical properties of carbon monoxide ?
Answer» SOLUTION :(i) Colour (II) Smell (III) VAPOUR density (iv) Solubility (v) Litmus test (vi) Nature

Discussion

78.	Who discovered neutrons ? How was the discovery made ?
Answer» SOLUTION :BOMBARDING Be NUCLEUS with `ALPHA` PARTICLES

Discussion

79.	The specific charge value of anode rays produced by _______ is the maximum.
Answer» ANSWER :HYDROGEN

Discussion

80.	Write in detail about the compounds formed by phosphorous and their uses.
Answer» Solution :(i) Phosphorous oxides. (ii) Phosphorous ACIDS. (III) Salts of acids. . (iv) Metal PHOSPHATES, metal PHOSPHATE, super phosphates. (v) Dehydrating AGENT, pharmaceuticals, petroleum field.

Discussion

81.	Water gas is mixture of
Answer» `CO_(2) and H_(2)` `H_(2) and CH_(4)` `CO and H_(2)` `CO and N_(2)` Solution :WATER GAS is a mixture of CO and `H_(2)`.

Discussion

82.	What is the valency of the two elements involved in this reaction? Mg+ O_2 toMgO
Answer» SOLUTION :VALENCY of both MAGNESIUM and OXYGEN is 2.

Discussion

83.	What type of ions do the following form? (i) a metal (ii) a non-metal
Answer» SOLUTION :(i) POSITIVE (II) NEGATIVE

Discussion

84.	Tiny diamonds fine applications in coating the tips and edges of cutting tools. Which properties of diamonds are made use of for this purpose ?
Answer» Solution :(i) PROPERTIES of cutting tools. (ii) CHARACTERISTICS of TOOL used for cutting. (iii) Arrangement of atoms in DIAMOND.

Discussion

85.	Which of the following compounds produces oxide on heating?
Answer» `PbO_(2)` `KNO_(3)` `Ag_(2)O` `NaNO_(3)` Solution :`2PbO_(2)to2P bO+O_(2)` `2KNO_(3)to2KNO_(2)+O_(2)` `2Ag_(2)Oto4Ag+O_(2)` `2NaNO_(3)to2NANO_(2)+O_(2)`

Discussion

86.	The temperature at which a liquid changes into a gas on heating at normal atmospheric pressure is called the ________ of that liquid.
Answer» SOLUTION :BOILING POINT

Discussion

87.	Which of the following uni-positive ions possesses all the three sub-atomicparticles
Answer» Helium Deuterium Tritium Hydrogen Answer :A::C

Discussion

88.	What is coal tar?
Answer» Answer :coal tar is a by product of coal. It is a black, THICK liquid with an UNPLEASANT smell. It is a mixture of around 200 SUBSTANCES

Discussion

89.	When the canal ray experiment was conducted by taking helium gas in the discharge tube, e/m value of the particles was found to be less under low voltage and it was found to be more under highvoltage . How do you explainthis ?
Answer» Solution :(i) The amount of energy required to cause ionisation . (II) Factors affecting e/m VALUES (III) Charge on helium gas under low PRESSURE and high pressure. (iv) The EFFECT of charge on e/m.

Discussion

90.	Which among the following types of glass is used in the manufacture of doors and windows 0f automobiles?
Answer» LAMINATED glass Fibre glass Foam glass Opaque glass Solution :Laminated glass is used in the manufacture of doors and WINDOWS of AUTOMOBILES becauseit PROVIDES good strength to the glass.

Discussion

91.	What is acrylic?
Answer» Answer :ACRYLIC is a type of synthetic FIBRE that resembles NATURAL wool.

Discussion

92.	What is cellulose?
Answer» ANSWER :A natural polymer which is made of a LARGE NUMBER of GLUCOSE UNITS is called cellulose.

Discussion

93.	When electric current is passed through water, it undergoes a …………….. Reaction.
Answer» SOLUTION :DECOMPOSITION

Discussion

94.	Visit five familiies in your neighbourhood and enquire about the kind of clothes they use, the reason for their choice and advantages of using them in terms of cost, durability and maintenance. Make a short report and submit it to your teacher.
Answer» ANSWER :STUDENTS SHALL do themselves.

Discussion

95.	What are the advantages of synthetic fibres over natural fibres
Answer» SOLUTION :LARGE SCALE PRODUCTION, cost, durability

Discussion

96.	Write the differences between reduction and oxidation.
Answer» Solution :(i) Addition of OXYGEN. removal of HYDROGEN is OXIDATION (ii) Removal of oxygen , addition of hydrogen is reduction

Discussion

97.	What was the aim of the Ganga Action Plan?
Answer» Answer :The aim of the Ganga ACTION Plan was to REDUCE the POLLUTION levels in the RIVER Ganga.

Discussion

98.	What is meant by oxidation and reduction?
Answer» SOLUTION :Oxidation-addition of mrygen, Reductionremoval of OXYGEN

Discussion

99.	Write one disadvantge of synthetic fibres.
Answer» SYNTHETIC FIBRES are very expensive. Synthetic fibres MELT on heating. Synthetic fibres are LESS durable. Synthetic fibres cannot be washed. Answer :B

Discussion

100.	Write the characteristics of chemical reaction.
Answer» Solution :(i) NEW SUBSTANCES FORMED. (II) Energy changes.

Discussion

Explore topic-wise InterviewSolutions in .

Though coke is made from coal, it is used for metallurgical processes instead of coal. Give reason.

Valency of a carbonate (CO_(3)) radical is

Write the reaction involved in the preparation of silicon carbide .

Which of the following is a pure substance?

Thesolubility of CaSO_(4)

Why are diesel and petrol replaced by CNG as fuels in automobiles?

What are catalytic reactions? Give an example.

The valencies of sulphur in hydrogen sulphide and sulphur dioxide are___________ and __________ respectively.

Which postulate of Dalton's atomic theory is considered to be correct even now?

Tincture of iodine is a mixture of ________and________.

Water is sprayed in orange grooves in very cold countries during winter. Give reasons.

What happens during rusting and .burning of magnesium ribbon?

X+O_(2)toY,Y+H_(2)OtoZ,Z turns red litmus to blue then X may be

What is the maximum number of electrons that can be present in the nth shell of an atom?

The temperature of troposphere decrease with increase in altitude. Is the same true of stratosphere? Justify.

What is plastic? Write a short note on different categories ofplastic.

What is acrylic? Why are they widely used?

what is coke?

Which of the following is false regarding epoxy resin?

Write the steps in naming a binary compound formed by two non-metallic ekmcnts, except hydrogen, with the help of an example .

Which of the following elements is used for vulcanization?

What is chemical decomposition? Give one example.

Though the dust particles cause air pollution, the presence of dust particles help in sustenance of life. Explain.

Which of the following are used in air conditioning and refrigeration systems?

What is the advantage of liquid CO_(2) fire extinguisher over soda-acid fire extinguisher? Explain.

What are the physical properties of carbon monoxide ?

Who discovered neutrons ? How was the discovery made ?

The specific charge value of anode rays produced by _______ is the maximum.

Write in detail about the compounds formed by phosphorous and their uses.

Water gas is mixture of

What is the valency of the two elements involved in this reaction? Mg+ O_2 toMgO

What type of ions do the following form? (i) a metal (ii) a non-metal

Tiny diamonds fine applications in coating the tips and edges of cutting tools. Which properties of diamonds are made use of for this purpose ?

Which of the following compounds produces oxide on heating?

The temperature at which a liquid changes into a gas on heating at normal atmospheric pressure is called the ________ of that liquid.

Which of the following uni-positive ions possesses all the three sub-atomicparticles

What is coal tar?

When the canal ray experiment was conducted by taking helium gas in the discharge tube, e/m value of the particles was found to be less under low voltage and it was found to be more under highvoltage . How do you explainthis ?

Which among the following types of glass is used in the manufacture of doors and windows 0f automobiles?

What is acrylic?

What is cellulose?

When electric current is passed through water, it undergoes a …………….. Reaction.

Visit five familiies in your neighbourhood and enquire about the kind of clothes they use, the reason for their choice and advantages of using them in terms of cost, durability and maintenance. Make a short report and submit it to your teacher.

What are the advantages of synthetic fibres over natural fibres

Write the differences between reduction and oxidation.

What was the aim of the Ganga Action Plan?

What is meant by oxidation and reduction?

Write one disadvantge of synthetic fibres.

Write the characteristics of chemical reaction.

The valencies of sulphur in hydrogen sulphide and sulphur dioxide are_ and respectively.

Tincture of iodine is a mixture of and.