1214 + Interview Questions in Chemistry in Class 8 Page 3 InterviewSolution

101.	Valency of sulphur in SO_2 is 2.
Answer» ANSWER :FALSE

Discussion

102.	What is the shape of the meniscus observed when water and mercury are taken in two differentcapillary tubes and why?
Answer» SOLUTION :(i) Type of forces between Hg MOLECULES and Hg-glass molecules. (ii) Type of forces between WATER molecules and water-glass molecules. (iii) Effect of these forces on the shape of MENISCUS.

Discussion

103.	When water, containing equal amounts of CO_(2), O_(2), NO_(2), N_(2)O_(3)gases respectively , subjected to heating, which gas is evolved out in maximum precentage ? Give reason.
Answer» Solution :(i) Comparision of reactivity of GASES with water. (ii) Conditions required for any gas to be present is maximum percentages in water. (iii) Relation between solubility of the gas and TEMPERATURE. (IV) EFFECT of heating on rise in temperature on the gases present.

Discussion

104.	The velocity of alpha particels increases then angle of deviation
Answer» increases decreases remains same Cannot be predicated Answer :B::C

Discussion

105.	What is S.I. unit for atmospheric pressure? Define it.
Answer» SOLUTION :Pascal. One NEWTON of FORCE acting per SQUARE metre of SURFACE area.

Discussion

106.	Write the steps in naming oxyacids , (i) with greater number of oxygen atoms and (ii) with less number of oxygen atoms.
Answer» SOLUTION :(i) CORRESPONDING prefix (II) Comparison with other OXYACIDS

Discussion

107.	What is the change that takes place when common salt is dissolved in water?
Answer» SOLUTION :PHYSICAL CHANGE

Discussion

108.	Which of the following reactions is a synthesis reaction?
Answer» When STEAM is passed over red hot coke, a mixture of carbon monoxide and hydrogen 15 fomed . Sodium reacts with WATER co form sodium HYDROXIDE and hydrogen . When the milkof lime (CALCIUM hydroxide) is added to hot sodium carbonate solution, sodium hydroxide is obtained and calcium carbonate separates out as mud. Stannic chloride is perpared by passing chlorine into molten tin. Answer :C::D

Discussion

109.	What is smog?
Answer» ANSWER :A thick fog-like LAYER in the atmosphere ESPECIALLY SEEN during winters which is made of smoke and fog is known as SMOG.

Discussion

110.	What are thermoplastics? Give examples. Where are they used?
Answer» Answer :THERMOPLASTICS are a TYPE of PLASTIC which can be moulded into different shapes on heating and canbe BENT easily. For example, polythene and PVC.

Discussion

111.	What happens when mercuric oxide is subjected to heating?
Answer» SOLUTION :FORMATION of MIRROR LIKE SURFACE.

Discussion

112.	Tick true/false against the following statements. Kerosene is not a fossil fuel.
Answer» ANSWER :F

Discussion

113.	What is an inhibitor? What is the inhibitor used in the preparation of H_2SO_4?
Answer» SOLUTION :DECREASES the RATE of REACTIONS.

Discussion

114.	What do you mean by solubility ?
Answer» SOLUTION :The maximum AMOUNT of a GIVEN solute in grams which can DISSOLVE 100 grams of solvent at a given TEMPERATURE.

Discussion

115.	What are synthetic fibres popularly used for making dress materials?
Answer» ANSWER :Synthetic fibres are popularly used for making DRESS mateials DUE to their special CHARACTERISTICS.

Discussion

116.	What were the comparative values of diameter of nucleus an atom given by Rutherford ?
Answer» SOLUTION :ANGSTROM, FERMI

Discussion

117.	What is explosion?
Answer» ANSWER :EXPLOSION is a kind of sudden reaction with the evolution of heat, light and SOUND, alongwith large amount of GAS. For example, PRESSURE applied on a cracker is a kind of explosion.

Discussion

118.	Tick true/false against the following statements. Coke is almost pure form of carbon.
Answer» ANSWER :T

Discussion

119.	Thetransition temperature ofrhombic and monoclinic sulphur "___________"
Answer» SOLUTION :`96.5^@`

Discussion

120.	What are the products obtained from coal?
Answer» Answer :Products such as coke. COAL tar and coal GAS can be OBTAINED from coal when it is PROCESSED in industry

Discussion

121.	When different gases are taken in the discharge tube, how do the e/m values of cathode rays and canal rays vary ?
Answer» SOLUTION :ATOMIC MASS

Discussion

122.	The valency of nitride ion is same as the valency of __________ ion
Answer» FERRIC plumbic zinc calcium Solution :Nitride : `N^(3-)` Ferric : `FE^(3+)` Whereas others are `Pb^(+4),ZN^(+2),Ca^(+2)`

Discussion

123.	Which among the following is true With regardingth ermoplastics and thermosettings
Answer» Thermosettings are permanent setting resins but THERMOPLASTICS are not, since they can be softened on cooling Thermoplastics are less brittle when compared to thermosettings due to the absence of long chain polymers. Thennosettings are more brittle When compared to thermoplastics due to the presence of strong bonds. The chemical nature of thermoplastics can be ALTERED by REPEATED heating and cooling Solution :Choice (3)

Discussion

124.	Which of the following changes directly from solid to gas on heating?
Answer» Ammonium chloride Sodium chloride Potassium chloride Calcium chloride Solution :Ammonium chloride is a sublimable SUBSTANCE which CHANGES DIRECTLY from solid to gas on heating.

Discussion

125.	The reducing property of SO_2 is shown in which of the following reactions
Answer» `SO_2+H_2O+CL_2rarr2HCL+H_2SO_4` `2H_2S +SO_2rarr2H_2O+3S` `KOH +SO_2rarr K_2SO_3+H_2O` NONE of the above SOLUTION :CHOICE( 1)

Discussion

126.	Where is the most polluted stretches of the river Ganga found?
Answer» Answer :The most POLLUTED STRETCHES of the RIVER GANGA is found at Kanpur in UTTAR Pradesh.

Discussion

127.	Which among the following properties of coke is exploited in the preparation of graphite by Acheson process ?
Answer» BAD conductor of ELECTRICITY Good conductor of electricity HIGHLY porous nature Low MELTING POINT Answer :A

Discussion

128.	What are chlorofluorocarbons?
Answer» Answer :Chlorofluorocarbons (CFCs) are the POLLUTANTS used in refrigerators, AIR CONDITIONERS and AEROSOL sprays. It DAMAGES the ozone layer of the atmosphere.

Discussion

129.	What is carbonisation ?
Answer» ANSWER :CARBONISATION is the process by which DEAD vegetation GETS converted into coal

Discussion

130.	What is meant by rusting? What are its effects? Explain different methods adopted for the prevention of rusting?
Answer» Solution :(i) Corrosion of iron in the PRESENCE of OXYGEN and mositure (ii) The formation of flakes and the weakening of iron STRUCTURES. (iii) Coating with different paints GALVANISATION, TINNING, electroplationg, alloying.

Discussion

131.	What is meant by oxy-hydrogen flame? For what purpose is it used?
Answer» Solution :BURNING MIXTURE of HYDROGEN and oxygen at high temperature. WELDING PURPOSE.

Discussion

132.	You are asked to prepare oxygen from air after eliminating the impurities in the order that is at first dust particles then water vapour and CO_(2) at the end. Based on the given instruction arrange the processes given below in a sequence. (a) Passing the sample of air through concentrated NaOH (b) Repeated compression followed by sudden expansion (c) Fractional distillation of liquefied air (d) Passing the air through electrostatic precipitator (e) Passing the air through anhydrous CaCl_(2)
Answer» a d e b c a c e b d d e a b c b a e d c SOLUTION :(i) Passing the air through electrostatic precipitator. (ii) Passing the air through anhydrous `CaCl_(2)`. (iii) Passing the air through concentrated NaOH solution . (iv) REPEATED compression FOLLOWED by SUDDEN expansion. (v) Frational distillation of LIQUEFIED air.

Discussion

133.	What is the valency of carbon?
Answer» 2 4 6 8 Answer :B

Discussion

134.	Why are ornaments prepared by using an alloy of Ag with Cu and not by pure Ag?
Answer» SOLUTION :(i) PHYSICAL properties of Ag. (ii) STRENGTH of ornaments made of PURE silver. (iii) Change in properties on the addition of Cu.

Discussion

135.	We learnt that magnesium burns to form magnesium oxide and produces heat and light. We can perform a similar activity with a piece of charcoal. Hold the piece with a pair of thongs and bring it near the flame of a candle or a Bunsen burner. Whit do you observe?
Answer» Answer :We notice that charcoal burns in AIR such as coal producing carbon dioxide, HEAT and LIGHT.

Discussion

136.	Which gas is present in the highest proportion in air?
Answer» Methane Nitrogen Oxygen Carbon DIOXIDE ANSWER :B

Discussion

137.	Which of the following fibres has properties similar to that of silk?
Answer» ANSWER :B

Discussion

138.	What do you mean by calorific value?
Answer» Answer : Calorific VALUE is the AMOUNT of heat energy PRODUCED by complete COMBUSTION of 1 kg of fuel Its unit is kilojoule per kilogram (kJ/kg).

Discussion

139.	Water remains as drops on the polythene surface but, it forms a thin layer on the surface of a properly cleaned glass plate. Explain.
Answer» SOLUTION :(i) COHESIVE, adhesive forces. (ii) Composition of polythene. (iii) Composition of glass. (iv) Forces between water and polythene. (V) Forces ACTING between water and glass. (vi) COMPARISON of these forces.

Discussion

140.	Which of the followingis not a mixture?
Answer» SODIUM CHLORIDE SOLUTION Brass Bronze MOLTEN sodium chloride Solution :Molten sodium chloride is a COMPOUND.

Discussion

141.	Write the balanced chemical equation for the following. (i) Potassium bromide on treatment with mangances dioxide and sulohuric acid gives manganese and potassium sulphates,bromine and water. (ii)In the preparation of phosphate fertilizes, calcium phosphate in phosphate rock is convertedinto phosphoric acid and calcium sulphate. (iii) Sodium nitrite is prodced by the reaction of the oxides of nitrogen in which nitrogen shows valency 2 and 4 in a solution of sodium carbonate.
Answer» Solution :(i)REACTANTS on left hand SIDE and products on right hand side. (II) Balancing the equations by keeping APPROPRIATE coefficients on EITHER side of reaction.

Discussion

142.	What is terylene?
Answer» ANSWER :TERYLENE is a familiar TYPE of ployester which can be DRAWN into very FIBRES and can be woven like any other yarn.

Discussion

143.	What are the essential requirements for producing fire?
Answer» ANSWER :The THREE essential requirements for PRODUCING fire are fuel, air and HEAT.

Discussion

144.	Water covers nearly........................% of earth.
Answer» ANSWER :0.71

Discussion

145.	What do you mean by polymer?
Answer» ANSWER :The WORD 'polymer' is derived from the two Greek WORDS 'poly' which MEANS 'many' and 'mer' MEANING part/unit.

Discussion

146.	What is the difference between latent heat of fusion and latent heat of vapourisation ? Discuss the difference taking water as an example.
Answer» Solution :Heat energy required for converting 1 G of ice to water. LATENT heat of FUSION of ice =80 cal/g Heat energy required for converting 1 g of water to vapour. Latent heat of vapourization =540 cal/g

Discussion

147.	what is a petroleum refinery ?
Answer» ANSWER :A petroleum REFINERY is a PLACE where the different COMPONENTS of petroleum are EXTRACTED

Discussion

148.	When ammonia gas is burnt in excess of oxygen at high temperature, the products formed are _______.
Answer» SOLUTION :`NO,H_(2)O`

Discussion

149.	Which among the following metals react only with steam ?
Answer» K Ca Mg Al Solution :ALUMINIUM METAL REACTS only with STEAM.

Discussion

150.	What do you observe when CaO and CaCl_(2) are exposed to mositure separately ?
Answer» Solution :Both CALCIUM oxide and calcium chloride absorb moisture , hence act as HYGROSCOPIC substances . Calcium chloride absorbs moisture anddissolves in it and changes its physical state. So it is called DELIQUESCENT substance. No change in physical state takes PLACE when calcium oxide absorbs moisture.

Discussion

Explore topic-wise InterviewSolutions in .

Valency of sulphur in SO_2 is 2.

What is the shape of the meniscus observed when water and mercury are taken in two differentcapillary tubes and why?

When water, containing equal amounts of CO_(2), O_(2), NO_(2), N_(2)O_(3)gases respectively , subjected to heating, which gas is evolved out in maximum precentage ? Give reason.

The velocity of alpha particels increases then angle of deviation

What is S.I. unit for atmospheric pressure? Define it.

Write the steps in naming oxyacids , (i) with greater number of oxygen atoms and (ii) with less number of oxygen atoms.

What is the change that takes place when common salt is dissolved in water?

Which of the following reactions is a synthesis reaction?

What is smog?

What are thermoplastics? Give examples. Where are they used?

What happens when mercuric oxide is subjected to heating?

Tick true/false against the following statements. Kerosene is not a fossil fuel.

What is an inhibitor? What is the inhibitor used in the preparation of H_2SO_4?

What do you mean by solubility ?

What are synthetic fibres popularly used for making dress materials?

What were the comparative values of diameter of nucleus an atom given by Rutherford ?

What is explosion?

Tick true/false against the following statements. Coke is almost pure form of carbon.

Thetransition temperature ofrhombic and monoclinic sulphur "___________"

What are the products obtained from coal?

When different gases are taken in the discharge tube, how do the e/m values of cathode rays and canal rays vary ?

The valency of nitride ion is same as the valency of __________ ion

Which among the following is true With regardingth ermoplastics and thermosettings

Which of the following changes directly from solid to gas on heating?

The reducing property of SO_2 is shown in which of the following reactions

Where is the most polluted stretches of the river Ganga found?

Which among the following properties of coke is exploited in the preparation of graphite by Acheson process ?

What are chlorofluorocarbons?

What is carbonisation ?

What is meant by rusting? What are its effects? Explain different methods adopted for the prevention of rusting?

What is meant by oxy-hydrogen flame? For what purpose is it used?

What is the valency of carbon?

Why are ornaments prepared by using an alloy of Ag with Cu and not by pure Ag?

We learnt that magnesium burns to form magnesium oxide and produces heat and light. We can perform a similar activity with a piece of charcoal. Hold the piece with a pair of thongs and bring it near the flame of a candle or a Bunsen burner. Whit do you observe?

Which gas is present in the highest proportion in air?

Which of the following fibres has properties similar to that of silk?

What do you mean by calorific value?

Water remains as drops on the polythene surface but, it forms a thin layer on the surface of a properly cleaned glass plate. Explain.

Which of the followingis not a mixture?

What is terylene?

What are the essential requirements for producing fire?

Water covers nearly........................% of earth.

What do you mean by polymer?

What is the difference between latent heat of fusion and latent heat of vapourisation ? Discuss the difference taking water as an example.

what is a petroleum refinery ?

When ammonia gas is burnt in excess of oxygen at high temperature, the products formed are _______.

Which among the following metals react only with steam ?

What do you observe when CaO and CaCl_(2) are exposed to mositure separately ?