908 + Interview Questions in Chemistry in Class 7

1.	Which compound amoung the following is used for the laboratory preparation of oxygen ?
Answer» `KNO_(3)` `PB(NO_(3))_(2)` `H_(2)O_(2)` `HgO` Solution :`H_(2)O_(2)` is used for the laboratory preparation of oxygen.

Discussion

2.	Two persons A and B got burns one with boiling water at 100^(@)C and other due to steam at 100^(@)C respectivley. Which person is affected more?
Answer» A B Both A and B to the same extent None of the above Solution :B will get severe burns as LATENT HEAT of vapourization of 540 cal/gis stored WITHIN the molecules of steam.

Discussion

3.	Underground water does not contain suspended impurities. Why?
Answer» SOLUTION :The UNDERGROUND water during seepage gets filtered through the layers of SOIL and HENCE does not contain suspended IMPURITIES.

Discussion

4.	Which of the following types of water is a bad conductor of electricity?
Answer» Distilled water Water obtained in ion-exchange PROCESS Mineral water Both 1 and 2 Solution :DEMINERALIZED water is obtained through ion-exchange process. Distilled and demineralized water doesn't contain any impurities. HENCE they do not conduct electricity. Mineral water isa good CONDUCTOR of electricity.

Discussion

5.	What is the action of heat on the following? (a) Ammonium hydroxide (b) Aluminium hydroxide (c) Sodium hydroxide
Answer» Solution :(a) Ammonium hydroxide decomposes rapidly to give AMMONIA gas and water upon slight heating. `NH_(4)OH overset(Delta)rarr NH_(3) + H_(2)O` (B) On heating aluminium hydroxide gives alumina and water. `2A1(OH)_(3) rarr A1_(2)O_(3) + 3H_(2)O` ltBrgt (c) NaOH melts on strong heating but it does not undego decomposition.

Discussion

6.	Which of the following substances used in agriculture does not cause water pollution to large extent?
Answer» Manures PESTICIDES Fertilizers Insecticides Solution :ADDING of manure to soil CAUSES less pollution because it is a organic matter and can be decomposed by MICRO organisms.

Discussion

7.	What is the role of water in the evolution of aquatic life?
Answer» SOLUTION :It is believed that complex chemical REACTIONS between the MINERALS in sea water took place in the presence o sunlight which RESULTED in the origin of unicellular organisms such as bacteria and fungi

Discussion

8.	Two volumes of hydrogen and one volume of oxygen compose one volume of water.
Answer» SOLUTION :`underset("volumes")underset("Two")(2H_(2))+underset("volume")underset("ONE")(O_(2))RARR underset("two volumes")(2H_(2)O)`

Discussion

9.	Which of the gas is the most unsuitable for filling up weather observation balloons ?
Answer» Helium Neon Hydrogen Argon Solution :Argon is unsuitable for FILLING up WEATHER OBSERVATION balloons because it is heavier than AIR.

Discussion

10.	Which of the following elements is chemically inactive ?
Answer» Nitrogen Neon Hydrogen Copper Solution :Insert geses like He , NE , AR are CHEMICALLY INACTIVE.

Discussion

11.	Write thecomposition of stainless steel.
Answer» Solution :STAINLESS STEEL is an alloy of `Fe (38%), Cr(15%), NI (1%) and C(1%)`.

Discussion

12.	Ultra violet rays are absorbed by ………….of atmosphere.
Answer» SOLUTION :ozonoshpere Ultra VIOLET RAYS are absorbed by ozonosphere of atmosphere

Discussion

13.	What is desalination?
Answer» Solution :The PROCESS of removal of dissolved salts from the SEA water is KNOWN as DESALINATION.

Discussion

14.	Which of the following is not the control measure of water pollution?
Answer» Usage of natural manure Usage of DRIP irrigation Usage of FERTILIZERS Usage of natural pesticides Solution :Usage of fertilizers is not the contro MEASURE for WATER pollution.

Discussion

15.	Which of the following terms is not related to underground water?
Answer» INFILTRATION Aquifer WATER table Potable water Solution :The TERM potable water is not related to UNDERGROUND water.

Discussion

16.	While coming back from school in the school in the school bus , Bill asked his friend Gill to predict the atoms, X andY while form a stable dinegative ion and a uninegative ion respectively . Theyhave same number of electrons in the L shell which is the shell inner to the valence shell . predict the answer given by gill .
Answer» Solution : `{:(,X^(-2),Y^(-1)),(E.C,2_(,)8_(,)8,2_(,)8_(,)8):}` Electronic configuration of corresponding neutral atoms , X and Y are as FOLLOWS : `Xto2, 8 , 6"" Yto2, 8 , 7` Atomic numbersof X and Y are 16and 17 respectively and hence they are SULPHUR and chlorine

Discussion

17.	Which of thefolllowing properties of silicon is not exploited in themanufacture of non-stick cookware ?
Answer» High resistance toheat. Poor electrical conductivity. Nonstick NATURE. High resistance tochemicals. SOLUTION :Silicone is a bad CONDUCTOR of electricity and this property is not exploited in the manufacture of nonstick cookware.

Discussion

18.	Water containing salt X of a divalent metal, when treated with a compound Y gives much lather with soap. Insoluble compound MgCO_(3) and salt of a monovalent metal sulphate are formed. Identify X and Y respectively.
Answer» `CaCl_(2), Na_(2)CO_(3)` `MgSO_(4), Na_(2)CO_(3)` `MgCl_(2), NaHCO_(3)` `CaSO_(4), Mg(HCO_(3))_(2)` SOLUTION :Divalent METAL SALT X that is, `MgSO_(4)` is treated with COMPOUND Y that is `Na_(2)CO_(3)` to form `MgCO_(3)` and `Na_(2)SO_(4)`. `MgSO_(4) + Na_(2)CO_(3) rarrMgCO_(3) + Na_(2)SO_(4)`.

Discussion

19.	Which among the following is a bad conductor of electricity ?
Answer» Zinc Copper Aluminium Phosphorus Solution :Generally, non-metals are BAD conductors of ELECTRICITY and HENCE phosphorus is a bad CONDUCTOR of electricity.

Discussion

20.	Which element is used in themanufacture of insecticides and pesticides and pesticides like DDT and BHC ?
Answer» Solution :CHLORINE is used in the MANUFACTURE of INSECTICIDES andpesticides like DDT and BHC.

Discussion

21.	Which of the following noble gases cannot be used for filling upelectric bulbs ?
Answer» Helium Neon Argon Radon Solution :Radon, being RADIOACTIVE, cannot be USED to FILL up ELECTRIC bulbs.

Discussion

22.	Though phosphorus acid contains three hydrogens, it is a dibasic acid. Give reasons.
Answer» SOLUTION :Formula of phosphorous ACID `H_(3)PO_(3)* H_(3)PO_(3)` on DISSOLUTION in water produces only two `H^(+)` ions. Only these two hydrogens are replaceable and the other hydrogen is non-replaceagle. Hence it is a DIBASIC acid.

Discussion

23.	Which of the following processes doen't contribute to the increase of supended pariculate matter in the atmophere ?
Answer» EMISSIONS from industries Burning of coal Burning of wood USAGE of REFRIGERATORS and AIR conditioners. Solution :The usage of refrigerators and air conditioners releases chloro CARBONS which doesn't contribute to SPM.

Discussion

24.	Which of the following is a noble gas ?
Answer» Hydrogen Helium Oxygen Nitrogen Solution :Helium is inert in NATURE and HENCE helium is a NOBLE GAS.

Discussion

25.	The water obtained in ion-exchange process is
Answer» devoid of dissolved salts and minerals devoid of only minerals potable called mineral water. Solution :In ION EXCHANGE method, pure water called demineralised water is OBTAINED which is not potable because it doesn't CONTAIN any minerals and dissolved salts.

Discussion

26.	Which of the following elements is used for tinning ?
Answer» Iron Tin Copper Aluminium Solution :The process of coating tin over any ARTICLE is CALLED TINNING.

Discussion

27.	Which among the following gases do not contribute to green house effect ?
Answer» METHANE CARBON DIOXIDE Water vapour Nitrogen dioxide Solution :Nitrogen dioxide present in the ATMOSPHERE does not CONTRIBUTE to acid rain.

Discussion

28.	Which of the following is a dibasic weak mineral acid?
Answer» acetic acid sulphurous acid phosphoric acid sulphurous acid Solution :The acids which are obtained from the minerals present in earth are called mineral acids. ONE MOLECULE of a dibasic acid furnishes two `H^(+)` ions and hence `H_(2)SO_(3)` is a dibasic mineral acid which is also a WEAK acid.

Discussion

29.	Water shows convex meniscus in narrow ________ and _________ tubes.
Answer» GLASS, plastic glass, wax COATED glass wax coated glass, plastic plastic, coloured glass Solution :In case of wax coated glass and plastic tube, cohesive FORCES are PREDOMINANT over adhesive forces and HENCE water shows convex meniscus in narrow wax coated glass tube and plastic tube.

Discussion

30.	Though zinc coating is cheaper than tin coating on iron, only tin coating for iron containersfor storing food meterials. Identify the correct reason.
Answer» Zinnce is LESS REACTIVE than tin. Zince acts as a preservative. Tin doesn't REACT with the components of FOOD meterial. Tin lowers the ambient TEMPERATURE and thus prevents spoilga of food. Solution :Tin doesn't react with the components of food meterial while Zn reacts and leads to spoilage of food. Hence tin coated containers are preferred over zinc coated ones as tin is less reactive than Zn,

Discussion

31.	Which of the following is a difference between thermoplastic and thermosetting plastics ?
Answer» Thermoplastics can be processed repeatedly THERMOSETTING PLASTICS cannot be SOFTENED by heating Thermo plastics do not UNDERGO chemical change on heating All the above. Solution :THERMOPLASTIC can be processed repeatedly, can be softened by heating and do not undergo any chemical change on heating .

Discussion

32.	Which of the following is a difference between thermoplastic andthermosetting plastics ?
Answer» Thermoplastics can be processed REPEATEDLY. Thermosetting plastics cannot be softened by HEATING . Thermoplastics do not UNDERGO CHEMICAL change on heating. All the above. Solution :Thermoplastic can be processed repeatedly, can be softened by heating and do not undergo any chemical change on heating.

Discussion

33.	What is intermolecular force of attraction ? Mention two types of intermolecular force of attraction acting between molecules.
Answer» Solution :The ATTRACTIVE forces that exist between the adjacent molecules of a MATTER are called INTERMOLECULAR forces depending on the nature of ATTRACTION can be of two types that is COHESIVE and adhesive forces depending on the nature of the participant molecules.

Discussion

34.	Though zinc coating is cheaper than tin coating on iron, only tin coating is used for iron containers for storing food materials. Identify the correct reason.
Answer» Zinc is less reaction than tin. Zinc acts as a preservative. Tin doesn't react with the COMPONENTS of food meterial. Tin LOWERS the ambient temperature and thus prevents spoilga of food. Solution :Tin diesn't react with the contents of food material while Zn reacts and leads to SPOILAGE of food. Hence in tin coated CONTAINERS are PREFERRED over zinc coated ones as tin is less reactive than Zn.

Discussion

35.	Which among the following statements is true ?
Answer» Compounds are HETEROGENEOUS in nature. The proportion of contituent elements in a compound is fixed. The CONSTITUENT elements retain their PROPERTIES in a compound. The formation of compount is a physical process. Solution :In compounds, the constituents are COMBINED in fixed weight ratio.

Discussion

36.	What happens when a paper soaked in acidified potassium dichromate is exposed to SO_(2) gas ?
Answer» Solution :When a PAPER soaked in ACIDIFIED potassium DICHROMATE paper dichromate paper is exposed to `SO_(2)` GAS, it turnsto green due to the formation of chromic sulphate.

Discussion

37.	What is meant by intermolecular space and intermolecular forces of attraction ?
Answer» SOLUTION :The space between the constituent MOLECULES of MATTER is called intermolecular space. The ATTRACTIVE FORCES that exist between the adjacent molecules of matter are called intermolecular forces of attraction .

Discussion

38.	What are mineral acids? How can they be further classified on the basis of nature of the constituents?
Answer» Solution :The acids which are SYNTHESISED from the minerals OBTAINED from earth's crust are called mineral acids. These mineral acids can be further CLASSIFIED on the basis of various characteristics. Based on the constituent elements in the acids they are classified as hydracids and oxyacids. The acids which contain hydrogen and ANOTHER nonmetal are called hydracids. The acids which contain oxygen along with hydrogen and nonmetal are called oxyacids.

Discussion

39.	While showing some common compounds used in our daily life in the laboratory, the teacher showed sodium chloride compound and told that it is also called common salt. Next day, one of the students brought common salt from home to the laboratory and requested the teacher to show sodium chloride as well. He kept both common salt and sodium chloride in two different watch glasses and left. Next day, during lunch break the student went to the laboratory and saw that the common salt brought from home became sticky whereas the compound sodium chloride remained as it is. What would be the justification given by the teacher for the above observation?
Answer» SOLUTION :In common SALT, trace AMOUNT of `MgC1_(2) "and" CaC1_(2)` are present as impurities which are deliquescent in NATURE. They absorb moisture from the surroundings and are converted to solution. As a RESULT common salt becomes sticky.

Discussion

40.	What is greenhouse effect ?
Answer» Solution :Certain gaseous molecules present in the ATMOSPHERE absorb IR rays and reradiate the HEAT in all DIRECTIONS and thus temperature of earth is maintained. This precess is called greenhouse effect.

Discussion

41.	Which of the following properties of iceberg led to the sinking of the titanic ship?
Answer» HEAVY water currents Relatively higher density of ice `9//10` of iceberg submerged below SEA water and `1//10` above the sea water None of the above Solution :ICEBERGS weigh million of tons but float on the surface of sea water because the density of ice is less than that of the sea water. Usually `9//10` of icebergs will be below the surface of water and `1//10` above the sea water as a result we cannot estimate the size below water, and hence when SHIP hits this heavier ice berg the ship sinks.

Discussion

42.	Which is a negative a radical among the following ?
Answer» Silcate Ammonium Ferrous Chromium Solution :Silicate is a NEGATIVE RADICAL i. E. `SiO_(3)^(-2)`.

Discussion

43.	What is a metalloid ? Give two examples.
Answer» Solution :Metalloids are ELEMENTS which show the PROPERTIES of both metals and non-metals. EXAMPLES : Germanium, ARSENIC

Discussion

44.	What is atmoshere ?
Answer» SOLUTION :The envelop of gases which surrounds the PLANET EARTH is CALLED atmophere.

Discussion

45.	Which of the following is a heterogeneous mixture ?
Answer» A mixture of water and sugar A mixture of water and COMMON salt A mixture of water and saw DUST A mixture of water and glucose Solution :Mixture of water and dust is a heterogeous mixture smnce saw dust is INSOLUBLE in water.

Discussion

46.	What is meant by electrolytic decomposition? Give an example.
Answer» Solution :ELECTROLYTIC decomposition is a CHEMICAL decomposition in which a single reactant is DECOMPOSED into more than one products by the passageof electricity. Example :`2H_(2)Oto2H_(2)+O_(2)`

Discussion

47.	Which of thefollowing involves only physical change ?
Answer» Dissolution of lime in WATER. Dissolution of CARBON dioxide in water at high pressure. Dissolution of CONCENTRATED acid in water. Electrolysis of water. Solution :Dissolution of any acid in water makes acid dilute. HENCE it involves only a PHYSICAL change.

Discussion

48.	Which of the following processes is not involved in making surface water potable?
Answer» SEDIMENTATION Chlorination Filtration DISTILLATION Solution :Distillation process is not involved in making surface water POTABLE.

Discussion

49.	The sculptures and monuments get demaged due to acid rains. Usage of scrubbers, containing lime, in industries decreases the percentage sontent of the major air pollutants that constribute to acid rain. The haracterstic reaction involved in the scrubber is ,
Answer» neutrazation oxidation reduction combination followed by decompositon. Solution :Marble is MADE of `CaCO_(2)` which gets dissolved when it reacts with acids like `H_(2)SO_(4)` or `HNO_(3)` of acid rains. The major POLLUTANTS which contribute to acid rain `NO_(2)" and "SO_(2)` are relesed into the atmosphere. The `NO_(2)" and "SO_(2)` percentage content in the atmosphere can be decreased by using equipment like scrubbers. It a scrubber, powdered `CaCO_(3)` is taken which undergoes decomposition to give CaO. This quick LIME cmbines with `SO_(2)" to form "CaSO_(3)` which is removed as slurry. `underset("Base")(CaO)+underset("acid")(SO_(2))toCaSO_(3)darr` Hence it is a neutralization reaction.

Discussion

50.	What are indicators? Give examples.
Answer» SOLUTION :Certain SUBSTANCES when added shows different colours in acidic and basic solutions. Such substances undergo COLOUR change at the neutralisation point which indicates the complete neutralisation and hence are called indicators. Certain naturally occurring substances can also act as indicators as they change colour according to the nature of substance. Example: Red cabbage juice. The other indicators used are litmus, methyl orange and phenolphthalein. Action of indicators on acids and bases `{:("NAME of indicator","Colour in acidic solution","Colour in basic solution"),("Litmus","Red","BLUE"),("Methyl orange","Pink (orange red)","Yellow"),("Phenolphthalein","Colourless","Pink"),("Turmeric","yellow","Red"):}`

Discussion

Explore topic-wise InterviewSolutions in Current Affairs.

Which compound amoung the following is used for the laboratory preparation of oxygen ?

Two persons A and B got burns one with boiling water at 100^(@)C and other due to steam at 100^(@)C respectivley. Which person is affected more?

Underground water does not contain suspended impurities. Why?

Which of the following types of water is a bad conductor of electricity?

What is the action of heat on the following? (a) Ammonium hydroxide (b) Aluminium hydroxide (c) Sodium hydroxide

Which of the following substances used in agriculture does not cause water pollution to large extent?

What is the role of water in the evolution of aquatic life?

Two volumes of hydrogen and one volume of oxygen compose one volume of water.

Which of the gas is the most unsuitable for filling up weather observation balloons ?

Which of the following elements is chemically inactive ?

Write thecomposition of stainless steel.

Ultra violet rays are absorbed by ………….of atmosphere.

What is desalination?

Which of the following is not the control measure of water pollution?

Which of the following terms is not related to underground water?

Which of thefolllowing properties of silicon is not exploited in themanufacture of non-stick cookware ?

Water containing salt X of a divalent metal, when treated with a compound Y gives much lather with soap. Insoluble compound MgCO_(3) and salt of a monovalent metal sulphate are formed. Identify X and Y respectively.

Which among the following is a bad conductor of electricity ?

Which element is used in themanufacture of insecticides and pesticides and pesticides like DDT and BHC ?

Which of the following noble gases cannot be used for filling upelectric bulbs ?

Though phosphorus acid contains three hydrogens, it is a dibasic acid. Give reasons.

Which of the following processes doen't contribute to the increase of supended pariculate matter in the atmophere ?

Which of the following is a noble gas ?

The water obtained in ion-exchange process is

Which of the following elements is used for tinning ?

Which among the following gases do not contribute to green house effect ?

Which of the following is a dibasic weak mineral acid?

Water shows convex meniscus in narrow ________ and _________ tubes.

Though zinc coating is cheaper than tin coating on iron, only tin coating for iron containersfor storing food meterials. Identify the correct reason.

Which of the following is a difference between thermoplastic and thermosetting plastics ?

Which of the following is a difference between thermoplastic andthermosetting plastics ?

What is intermolecular force of attraction ? Mention two types of intermolecular force of attraction acting between molecules.

Though zinc coating is cheaper than tin coating on iron, only tin coating is used for iron containers for storing food materials. Identify the correct reason.

Which among the following statements is true ?

What happens when a paper soaked in acidified potassium dichromate is exposed to SO_(2) gas ?

What is meant by intermolecular space and intermolecular forces of attraction ?

What are mineral acids? How can they be further classified on the basis of nature of the constituents?

What is greenhouse effect ?

Which of the following properties of iceberg led to the sinking of the titanic ship?

Which is a negative a radical among the following ?

What is a metalloid ? Give two examples.

What is atmoshere ?

Which of the following is a heterogeneous mixture ?

What is meant by electrolytic decomposition? Give an example.

Which of thefollowing involves only physical change ?

Which of the following processes is not involved in making surface water potable?

The sculptures and monuments get demaged due to acid rains. Usage of scrubbers, containing lime, in industries decreases the percentage sontent of the major air pollutants that constribute to acid rain. The haracterstic reaction involved in the scrubber is ,

What are indicators? Give examples.

Water shows convex meniscus in narrow and _ tubes.