1214 + Interview Questions in Chemistry in Class 8 Page 21 InterviewSolution

1001.	Compare solids, liquids and gases on the basis of their properties.
Answer» Solution :(i) Mass (ii) VOLUME (iii) SHAPE (iv) Density (v) Compressibility (vi) Free surface (VII) THERMAL expansion (VIII) Diffusion

Discussion

1002.	Compare metals and non-metals based on their physical properties.
Answer» Solution :(i) State (II) MELTING point and boiling point (iii) Conductivity (IV) TENSILE strength (v) Malleability and ductibility (vi) LUSTRE

Discussion

1003.	Compare and contrast the principleinvolved in the usage ofof NaHCO_(3) and dry ice for cleaning industrial equipments by blasting the given substances with compressed air.
Answer» Solution :Soda blasting is a technique employed to strip off the paints and UNWANTED materials from all surfaces. This technique involved blasting of `NaHCO_(3)` on the required SURFACE with the help of compressed air. Dry ice blasting is ALSO USED for the same purpose. But it is more advantageous than soda blasting because dry ice pellets sublime as soon as they are blasted on any surface leaving no residual matter on the surface. Since huge amount of heat is absorbed for sublimation process, thermal shock ( due to sudden contraction ) in generated in the coating which is an added advantages for the removal of unwanted coating.

Discussion

1004.	Compare and contrast and angle of deflection of alpha-rays in alpha-ray scattering experiment carried out by taking aluminium foil and gold foil. Justify.
Answer» Solution :In the normal `alpha`-ray scattering experiment, gold foil is used. In place of gold foil, if aluminium foil is used, the angle of DEFLECTION will be less. Than that of gold nucleus . So, the repulsive forces experienced by `alpha`-RAYS and the IMPACT due to the collision with the aluminium NUCLEI are less. Hence the angle of deflections will be less in `alpha`-ray scattering experiment using aluminium foil instead of gold foil.

Discussion

1005.	Compare and constrat the principle involved in the usage of NaHCO_(3) and dry ice for cleaning industrial equipments by blasting the given substances with compressed air.
Answer» Solution :(i) Effect on the unwanted coating due to the BLASTING of soda or dry ice. (ii) NATURE of sodium bicarbonate. (iii) Mechanical impact onthe industrial equipment due to blasting of `NaHCO_(3)` and dry ice. (iv)} Changes that takes place in dry ice after blasting. (V) Change in temperature due to the above phenomenon. (vi) Effect of change in temperature on the coating of IMPURITIES on the surface of industrial equipments.

Discussion

1006.	Common variety of coal called household coal.
Answer» ANSWER :Bimrninous COAL

Discussion

1007.	Coloured dye from ink is separated by the method of __________.
Answer» SOLUTION :CHROMATOGRAPHY

Discussion

1008.	Colour is imparted to diamond due to the presence of _______.
Answer» SOLUTION :IMPURITIES

Discussion

1009.	Colour changes observed during the reaction between metal oxides and hydrogen are given below (a) White to Bluish white(b) Brown toGrey (c) Yellow to Grey(d) Black to Red Arrange the above colour changes as PbO to Pb , Fe_(2)O_(3), to Fe, CuOto Cu and ZnO to Zn
Answer» c B d a c DA b c b a d b c d a Solution :`PbO + H_(2) to Pb + H_(2)O` Yellow `""` GREY `Fe_(2)O_(3)+H_(2) to Fe + H_(2)O` Brown `""`Grey `CuO + H_(2) to Cu + H_(2)O` Black `""` Red `ZnO + H_(2) to Zn + H_(2)O` White`""` Bluish white

Discussion

1010.	Colloid seems ..................... and the solute particles are ..................... to eyes.
Answer» ANSWER :CLOUDY, not VISIBLE

Discussion

1011.	Coke can be used as
Answer» an OXIDIZING AGENT a household FUEL printer ink electrodes. ANSWER :B

Discussion

1012.	Name three crystalline allotropes of carbon.
Answer» ANSWER :F

Discussion

1013.	Coating of tin over iron is called ______.
Answer» SOLUTION :TINNING

Discussion

1014.	CO_(2)+ H_(2)O to………….
Answer» ANSWER :`H_(2)CO_(3)`

Discussion

1015.	Clay shows plasticity when
Answer» right proportion of WATER is added to it. it is fired (strongly heated it is DRIED at ROOM TEMPERATURE after kneading. it is glazed Solution :Choice (1)

Discussion

1016.	Classify the following into physical and chemical changes. (i) Freezing of water(ii) Fermentation of alcohol (iii) Burning of coal(iv) Breaking of glass (v) Glowing of an electric bulb
Answer» Solution :(i) CHANGE in COMPOSITION (II) NEW products FORMATION.

Discussion

1017.	Choose the correct option ________is produced by incomplete combustion of fuel.
Answer» CARBON dioxide Carbon monoxide Sulphur Nitrogen ANSWER :A::B::C::D

Discussion

1018.	Choose the correct option ________is a supporter of combustion.
Answer» CNG Cooking gas Nitrogen Oxygen

Discussion

1019.	Choose the correct option ________ is a corrosive gas.
Answer» SULPHUR dioxide CNG Sulpher Nitrogen oxide Answer :D

Discussion

1020.	Choose the correct option ___________has the highest heat value.
Answer» COW DUNG cake Coal Sand Glass Answer :A::C

Discussion

1021.	Choose the correct option Global warming is caused by _______.
Answer» ACID rain combustion of fuels nuclear reaction inflamable substance Answer :B::C

Discussion

1022.	Chlorine is an element and sodium chloride is a compound.
Answer» ANSWER :T

Discussion

1023.	Chemical symbol of an element can be derived from its name
Answer» first letter first two letters Latin name EITHER of a, B or c ANSWER :D

Discussion

1024.	Chemical reaction in which two elements combine to form a new compound is known as a …………….. Reactions.
Answer» SOLUTION :COMBINATION or SYNTHESIS

Discussion

1025.	Chemical symbol of hydrogen is H_(2).
Answer» ANSWER :T

Discussion

1026.	Chemical formula of a compound can be derived, if we know the ……………. And the ……………. Of its constituent elements.
Answer» SOLUTION :SYMBOLS, VALENCIES

Discussion

1027.	Chemical equation can indicate the time taken by the reaction.
Answer» ANSWER :F

Discussion

1028.	Chemical compound that can be used to soften hard water.
Answer» ANSWER :WASHING SODA

Discussion

1029.	True or False:A chemical change is permanent and irreversible.
Answer» ANSWER :T

Discussion

1030.	Changing of solid ice into water.
Answer» SOLUTION :MELTING

Discussion

1031.	Changing of camphor directly from solid into vapour form.
Answer» SOLUTION :SUBLIMATION

Discussion

1032.	Changes in which new substances are formed are called …………. Changes.
Answer» SOLUTION :CHEMICAL

Discussion

1033.	Change in milk on adding lemon juice.
Answer» SOLUTION :CURDLING of MILK

Discussion

1034.	Certain phosphates are helpful in making hard water soft.Which phosphates are used and how do they help in making water soft?
Answer» Solution :SOLUBLE phosphates when added to HARD water form CALCIUM and magnesium phosphates, which are insoluble PRECIPITATES. Thus, as the calcium and magnesium ions are PRECIPITATED,the water becomes soft and can give lather with soap

Discussion

1035.	Certain gases dissolve in water by the process of _________.
Answer» SOLUTION :DIFFUSION

Discussion

1036.	Cathode rays have mass and possess kinetic energy.
Answer» ANSWER :T

Discussion

1037.	Cathode rays deflect in the presence of magnetic field.
Answer» ANSWER :1

Discussion

1038.	Cathode rays are deflected in electric and magnetic fields. But they are made to pass straight in Thomson's experiment . How do you account for this ?
Answer» SOLUTION :(i) Effect of equal strengths of electric FIELD and magneticfield. (ii) The effect of electric and magnetic field on cathode rays. (iii) The DIRECTIONOF APPLICATION of electric and magnetic field such that there is no.

Discussion

1039.	Carbon occurs as the native element in the earth's crust in the form of.
Answer» DIAMOND METHANE CARBON DIOXIDE GAS carbon. Answer :A

Discussion

1040.	Carbon monoxide is slightly _______ than air.
Answer» ANSWER :LIGHTER

Discussion

1041.	Carbon monoxide is neither combustible nor a supporter of cobustion.
Answer» ANSWER :FALSE

Discussion

1042.	Carbon monoxide gas can be detected by passing it through a blood sample. Explain.
Answer» Solution :(i) INTERACTION between CARBON MONOXIDE and haemoglobin. (ii) REACTION of CO with `O_(2)` carrier in blood. (III) Product formed. (iv) Colour of the product formed.

Discussion

1043.	Carbon dioxide is lighter than air.
Answer» ANSWER :F

Discussion

1044.	Carbon dioxide forms a snowy white solid called ..................... at -78°C.
Answer» ANSWER :DRY ICE

Discussion

1045.	Carbon dioxide dissolves in water to form
Answer» SULPHURIC acid hydrochloric acid carbonic acid carbon monoxide Answer :C

Discussion

1046.	Ca(OH)_(2) + CO_(2) to……………. + ……………
Answer» ANSWER :`CaCO_(3), H_(2)O`

Discussion

1047.	Canal rays are invisible rays emitted from the cathode.
Answer» ANSWER :F

Discussion

1048.	Can you store lemon pickle in an aluminium utensil? Explain.
Answer» ANSWER :LEMON pickle contains ACIDS which can spoil the pickle as it REACTS with aluminium liberating hydrogen gas. Therefore, lemon pickle cannot be STORED in aluminium utensils.

Discussion

1049.	Can you name some natural fibres?
Answer» ANSWER :Yes, some natural FIBRES are COTTON,WOOL,silk,linen, etc.

Discussion

1050.	Can you guess the sequence of metals from more reactive to less reactive among zinc, iron and copper?
Answer» Answer :Among zinc, iron and copper, the sequence of METALS from more reactive to LESS reactive are GIVEN below : `Zn>Cu>FE`

Discussion

Explore topic-wise InterviewSolutions in .

Compare solids, liquids and gases on the basis of their properties.

Compare metals and non-metals based on their physical properties.

Compare and contrast the principleinvolved in the usage ofof NaHCO_(3) and dry ice for cleaning industrial equipments by blasting the given substances with compressed air.

Compare and contrast and angle of deflection of alpha-rays in alpha-ray scattering experiment carried out by taking aluminium foil and gold foil. Justify.

Compare and constrat the principle involved in the usage of NaHCO_(3) and dry ice for cleaning industrial equipments by blasting the given substances with compressed air.

Common variety of coal called household coal.

Coloured dye from ink is separated by the method of __________.

Colour is imparted to diamond due to the presence of _______.

Colour changes observed during the reaction between metal oxides and hydrogen are given below (a) White to Bluish white(b) Brown toGrey (c) Yellow to Grey(d) Black to Red Arrange the above colour changes as PbO to Pb , Fe_(2)O_(3), to Fe, CuOto Cu and ZnO to Zn

Colloid seems ..................... and the solute particles are ..................... to eyes.

Coke can be used as

Name three crystalline allotropes of carbon.

Coating of tin over iron is called ______.

CO_(2)+ H_(2)O to………….

Clay shows plasticity when

Classify the following into physical and chemical changes. (i) Freezing of water(ii) Fermentation of alcohol (iii) Burning of coal(iv) Breaking of glass (v) Glowing of an electric bulb

Choose the correct option ________is produced by incomplete combustion of fuel.

Choose the correct option ________is a supporter of combustion.

Choose the correct option ________ is a corrosive gas.

Choose the correct option ___________has the highest heat value.

Choose the correct option Global warming is caused by _______.

Chlorine is an element and sodium chloride is a compound.

Chemical symbol of an element can be derived from its name

Chemical reaction in which two elements combine to form a new compound is known as a …………….. Reactions.

Chemical symbol of hydrogen is H_(2).

Chemical formula of a compound can be derived, if we know the ……………. And the ……………. Of its constituent elements.

Chemical equation can indicate the time taken by the reaction.

Chemical compound that can be used to soften hard water.

True or False:A chemical change is permanent and irreversible.

Changing of solid ice into water.

Changing of camphor directly from solid into vapour form.

Changes in which new substances are formed are called …………. Changes.

Change in milk on adding lemon juice.

Certain phosphates are helpful in making hard water soft.Which phosphates are used and how do they help in making water soft?

Certain gases dissolve in water by the process of _________.

Cathode rays have mass and possess kinetic energy.

Cathode rays deflect in the presence of magnetic field.

Cathode rays are deflected in electric and magnetic fields. But they are made to pass straight in Thomson's experiment . How do you account for this ?

Carbon occurs as the native element in the earth's crust in the form of.

Carbon monoxide is slightly _______ than air.

Carbon monoxide is neither combustible nor a supporter of cobustion.

Carbon monoxide gas can be detected by passing it through a blood sample. Explain.

Carbon dioxide is lighter than air.

Carbon dioxide forms a snowy white solid called ..................... at -78°C.

Carbon dioxide dissolves in water to form

Ca(OH)_(2) + CO_(2) to……………. + ……………

Canal rays are invisible rays emitted from the cathode.

Can you store lemon pickle in an aluminium utensil? Explain.

Can you name some natural fibres?

Can you guess the sequence of metals from more reactive to less reactive among zinc, iron and copper?