908 + Interview Questions in Chemistry in Class 7

1.	Arrange the steps in sequence for the manufacture of cement. (a)Mixture is pulverized using a pulverizer. (b)Limestone and clay are mixed in a definite proportion. (c)Mixture is heated to1500^(@) C " to " 1600^(@)C to form clinkers. (d) Clinkers are pulverizedto form fine powder and a small quantity of gypsum is added.
Answer» a c B d b a c d b d c a d c b a Solution :(a) Limestone and CLAY are mixed in a definite proportion. (b) Mixture is pulverized USING a pulverizer. (c) Mixture is heated to ` 1500^(@) c " to " 1600^(@) C` to from CLINKERS. (d) Clinkers are pulverized to form fine powder and a SMALL quantity of gypsum is added. Choice

Discussion

2.	Arrange the steps in sequence for the manufacture of borosilicate glass. (a) Addition of ingredients like red lead, aluminium oxide, manganese oxide, chromium oxide etc. (b)Addition of broken pieces of glass (c)Mixing up of sand, limestone, sodium carbonate, aluminium oxide and borax in required proportion (d)Melting mixture in a glass tank furnace or pot furnace (e ) Annealing process (f) Blowing of glass
Answer» cbadfe cbafed cdbafe cfebad Solution :(i) Mixing up of sand, LIMESTONE, SODIUM carbonate, aluminium oxide and borax in required proportion. (ii) addition of BROKEN pieces of glass (iii) Addition of ingredients like red lead, aluminium oxide, manganes oxide, chrominum oxide ETC. (iv)Melting mixture in a glass tank furnace orpot furnace. (v) Blowingof glass (VI) Annealing process

Discussion

3.	Arrange the steps in sequence for the manufacture of cement. (a)Mixture is pulverized usinga pulverizer. (b)Limestone and clay are mixed in a definite proportion. (c)Mixture is heated to1500^(@)C" to "1600^(@)C to form clinkers. (d) Clinkers are pulverized to from fine powder and a small quantity of gypsum is added.
Answer» acbd bacd bdca dcba Solution :(i) Limestone and clay are mixed in a definite proportion. (II) Mixture is pulverized using a pulverizer . (iii) Mixture is HEATED to ` 1500^(@)C"to" 1600^(@)C` to from clinkers. (iv) Clinkers are pulverized to form fine powder and a small quantity of gypsum is added.

Discussion

4.	Arrange the steps in sequence for the manufacture of borosilicate glass. (a)Addition of ingredients like red lead, aluminium oxide, manganese oxide, chromium oxide etc (b)Addition of broken pieces of glass (c)Mixing up of sand, limestone, sodium carbonate, aluminium oxide and borax in required proportion (d) Melting mixture in a glass tankfurnace or pot furnace (e ) Annealing process (f) Blowing of glass
Answer» c b a d f e c b a f e d c d b a f e c f e b a d Solution :(a) Mixing up of sand limestone, SODIUM carbonate aluminium oxide and BORAX in required proportion. (b) Addition of broken pieces of glass (c) Addition of INGREDIENTS like red lead, aluminium oxide manganese oxide, chromium oxide etc (d) Melting mixture in a glass TANK furnace or pot furnace. (f) BLOWING of glass (e) Annealing process

Discussion

5.	Arrange the steps in a sequence for the removal of microorganisms during the purification of drinking water. (a) Lime feeder(b) Mechanical mixing(c ) Alum feeder(d) Sedimentation tank(e) Passing through gravel and sand (f) Chlorine feeder
Answer» C a b d e f c b a d e f e a b c f d a b d c e f Solution :(i) Alum feeder(ii) Lime feeder (iii) Mechanical MIXING(iv) Sedimentation TANK (v) Passing through gravel and SAND(vi)Chlorine feeder

Discussion

6.	Arrange the steps in a sequence for the conversion of atmospheric water vapour into underground water. (a) Infiltration in recharge area (b) Water table (c ) Infiltration in zone of aeration (d) Precipitation(e) Aquifer
Answer» d a c b e d c a b e d c a e b d a c e b Solution :(i) PRECIPITATION (ii) Infiltration in ZONE of aeration (iii) Infiltration in RECHARGE AREA (iv) Water table (v) Aquifer

Discussion

7.	Arrange the steps in a sequence for the formation of rainfall.(a) Formation of micelles(b) Condensation(c ) Evaporation(d) Formation of clouds (e) Precipitation
Answer» c E d b a c b d a e c b a d e a b c e d Solution :(i) Evaporation (ii) Condensation (III) Formation of micelles (IV) Formation of CLOUDS (v) Precipitation

Discussion

8.	Arrange the staps in sequence for the manufacture fo glass.
Answer» Addition of CULLET Mixing of RAW materials in proper proportion Addition of COLOURING pigments Annealing Solution :(i) Mixing of RAWMATERIALS in proper proportion (ii) Additon of cullet (iii) Addition of colour pigments (iv) Annealing

Discussion

9.	Arrange the process in sequence for the purification of drinking water (a) Lime feeder, alum feeder(b) Filtration(c ) Mechanical mixing(d) Chlorination
Answer» abcd abdc bcde bcda Solution :(i) Lime FEEDER, alum feeder(ii) Mechanical MIXING (iii) FILTRATION(IV) CHLORINATION

Discussion

10.	Arrange the relevant steps in correct sequence for themanufacture of sodium chloride from sea water. (a) Making of hot saturated solution (b) Evaporation (c) Recrystallization (d) Collection of sea water (e ) Addition of small quantity of sodium iodide or potassium iodide
Answer» d E b a d e b c d e a b c d b a c Solution :(d) Collection of SEA water (b) Evaporation (a) MAKING of hot saturated solution (c) RECRYSTALLIZATION

Discussion

11.	Arrange the points in sequence to draw the geometrical representation of an atom which is resprecented as _(Z)X^(A).(a)Calculation of the numberof protons and neutrons.(b)Identification of the atomic number and mass number of the given element.( c) Placement of the electrons in shells aroundthe nucleus according to the electronic configuration.(d)Wirting the electronc configuration of the atom.(e) Protons and neutrons are shown in nuleus.
Answer» baedc bacde abcde ecbad Solution :(i) Identification of the atomic number and the mass number of the given element. (ii) Calculation of the number of protons and NEUTRONS. Protons and neutrons are SHOW in nucleus. (III) Protons and neutrons are show in nucleus. (iv) Placement of the ELECTRONS in SHELLS around the nucleus according to the electronic configuration.

Discussion

12.	Arrange the points in sequence to draw the geometrical representation representation of_(20)Ca^(40).(a) Protons and neutrons are shown in the nucleus.(b) Writing the electronic configuration of the atom.(c ) Arrange the electrons in shells around the nucleus following the electronic configuration.(d) Calculation of the number of protons and neutrons.(e ) Identification of the atomic number and mass number of the atom.
Answer» edcba edabc abcde cabde Solution :(i)Identification of the atomic numberand mass number of the ATOM. (ii) Calculation of the number of protons and NEUTRONS. (iii)Protons and neutrons are shown in the nucleus. (iv) Writing the ELECTRONIC configuration of the atom. (v)ARRANGE the electronis in SHELLS around the nucleus following the electronic configuration.

Discussion

13.	Arrange the pairs in sequence in decreasing order of basicity of an acid and acidity of a base followed by the normal salts formed by the given acid base pairs in the same order respectively. (a) Acetic acid, ammonium hydroxide (b) Oxalic acid, barium hydroxide (c) Phosphoric acid, aluminium hydroxide (d) Barium oxalate (e) Ammonium acetate (f) Aluminium phosphate
Answer» adcfe cbafde adcebf cdaebf Solution :(i) Phosphoric acid, aluminium HYDROXIDE (ii) OXALIC acid, barium hydroxide (iii) ACETIC acid, ammonium hydrozide (iv) Ammonium ACETATE (v) Barium oxalate (vi) Aluminium phosphate

Discussion

14.	Arrange the pairs in sequence in decreasing order of base and increasing order of basicity of an acid and the salts formed between an acid and base with equal basicityand acidity in their increasing order respectively. (a) Sodium chloride (b) Barium hydroxide, sulphuric acid (c) Ferric phosphate (d) Ferric hydroxide, hydrochloric acid (e) Barium sulphate (f) Sodium hydroxide, phosphoric acid
Answer» dbfaec fbdaec dbfcea fbdcea Solution :(i) Ferric hydroxide, hydrochloric acid ltBrgt (II) Barium hydroxide, sulpheric acid (iii) SODIUM hydroxide, PHOSPHORIC acid. (iv) Sodium chloride (v) Barium SULPHATE (vi) Ferric phosphate

Discussion

15.	Arrange the layers of the atmosphere as per the following terms related in a sequence order respectively. Inversion layer, convertion currents, absorbs harmful radiations and burning up of meteorites (a) Troposphere (b) Stratophere ( c) Exophere (d) Mesosphere (e ) Ionophere
Answer» decab abced baecd abdce Solution :(i) Stratosphere (II) Troposphere (III) IONOSPHERE (iv) Exosphere (V) Mesophere

Discussion

16.	Arrange the given compounds inthe increasing order of carbon atoms present in the compounds (a) Methane (b) Suger (c) Glucose (d) Starch
Answer» `bltclt DLT a` `CLT alt blt d` `alt clt blt d` `blt dlt alt C` Solution :(a) Methane (c) Glucose (b) Sugar (d) STARCH

Discussion

17.	Arrange the general steps for the purification of water in a sequence. (a) Filtration(b) Chlorination (c ) Sedimentation (d) Addition of chemicals
Answer» a C b d c a b d c d a b a b d c Solution :(i) Sedimentation (ii) Addition of CHEMICALS (iii) FILTRATION (IV) Chlorination

Discussion

18.	Arrange the following terms in sequence from source to supply. (a) Chlorination (b) Sedimentation (c ) Filtration(d) Storage water tank (e) Lakes
Answer» ecadb acbde ebcad bcade Solution :(i) Lakes (ii) Sedimentation (iii) FILTRATION (iv) CHLORINATION (v) Storage water TANK

Discussion

19.	Arrange the following substance in the ascending order of the number of constituent element(s) present in them. (a) Sodium bicarbonate, (b) Calcium carbonate ( c) Water, (d) Copper
Answer» d,C,b,a c,b,a,d b,a,d,c a,b,c,d Solution :d,c,b,a (i) Copper (ii) WATER (iii) Calcium CARBONATE (iv) Sodium bicarbonate

Discussion

20.	Arrange the following sequence in orderto derive the formula of zine oxide.(a)The valencies of ions formed by zine and oxygen are written below without positive and negative sign.(b)The positive ion that isZn^(+2)followed by the negative ion , that is oxide(O^(-2)ion are written with ther charges.(c )The valencies of zinc and oxide ion have common factors and hence they aredivided by their highest common factor.(d)The magnitudeof valencies of the ions should be interchanged and written as subscripts on right sideof the respective ions.
Answer» badc abcd bacd cabd Solution :(i) The posiitive ion that is `Zn^(+2)` followed by the negative ion that is `O^(-2)`are written with their charges. (ii)The VALENCIES of ions formed by zine and oxygen and are written below without positive and negative sign.(iii) The valencies of ZINC and oixde have common factors and hence they are divided by the HIGHEST common FACTOR. (iv)The magnitude of the valenciesof the ions should be interchanged and written as SUBSCRIPTS on right side of the respective ions.

Discussion

21.	Arrange the following point in sequence for derivation of formulae of compounds.(a) The valencies of the ions or radicals are written below the radicals without positive and negative sing.(b)If the valencies have common factors , they are divided by the highest common factor.(c ) The magnitude of valencies should be interchanged and writtenassubscripts on the right side of the respective ions.(d) The positive radical followed by negative radical are written with their chatges.(e)If the radicals contain more than one atom , they are enclosed in brackets and the appropriate valency (more than one ) written assubscripts outside the bracket.
Answer» bcdea dacbe abcde dabce Solution :(i) The positive radical followied by negative radicalare written with their charges. (ii)The valencies of the ions or radicals are written below the radicals without positive and negative sign. (iii) The magnitude of valencies should be interchanged and written as subscripts on the right SIDE of the respective ions. (iv)If the valencies have common factors , they are dividedby the HIGHEST common factor. (v)If the radicals CONTAIN more than one atom , they are enclosed in brackets and the appropriate VALENCY (more than one) written as subscript outside the BRACKET.

Discussion

22.	Arrange the following layers of the atmophere in the decreasing order of their altitudes. (a) Stratosphere (b) Troposphere ( c)Mesophere (d) Exosphere ( e) Ionophere
Answer» cdeab baced dbeca decab Solution :(i) Exosphere (ii) Ionosphere (III) Mesophere (iv) Stratophere (v) Troposphere

Discussion

23.	Arrange the following in a proper sequence for the separation of constituents of gun powder (a) Carbon disulphide is added to the mixture (b) Carbon powder is separated (c ) Residue is filtered (d) KNO_(3) is separated from its aqueous solution by heating it (e) Mixture is filtered and hot water is added to the residue
Answer» aedbc aecbd abcd None of these Solution :(i) Carbon disulphide is added to the MIXTURE (ii) Mixture is filtered and hot water is added to the RESIDUE (iii) Residue is filtered (IV) Carbon powder is SEPARATED (v) `KNO_(3)` is separated from its aqueous solution by heating it

Discussion

24.	Arrange the following given reactions in a sequence for the process of nitrogen fixation. (A) Formation of metal nitrates (B) Formation of nitrogen doxide. ( C) Formation of itric oxide (D) Formation of nitric acid
Answer» cbad cbda badc dbac Solution :(i) Formation of NITRIC oxide (II) Formation of nitrogen dioxide (iii) Formation of nitric ACID (iv) Formation of metal NITRATES

Discussion

25.	Arrange the following equations in the correct sequence to obtain a normal salt. (a) A1(OH)C1_(2) + HCI rarr A1C1_(3) + H_(2)O (b) A1(OH)_(3) + HC1 rarr A1(OH)_(2)C1 + H_(2)O (c) A1(OH)_(2)C1 + HC1 rarr A1(OH)C1_(2) + H_(2)O
Answer» CBA bca abc cab Solution :(i) `AI(OH)_(3) + HCI RARR AI(OH)_(2)CI + H_(2)O` (II) `AI(OH)_(2)CI + HCI rarr AI(OH)CI_(2) + H_(2)O` (iii) `AI(OH)CI_(2) + HCI rarr AICI_(3) + H_(2)O`

Discussion

26.	Arrange the following examples in the oredr of matter, compound, element and mixture. (a) Dilute acid, (b) Argon (c ) Water, (d) Ball
Answer» a,C,b,d d,c,b,a a,b,d,c d,c,a,b Solution :d,c,b,a (i) Ball (ii) Water (iii) Argon (IV) DILUTE acid

Discussion

27.	Arrange the following equations in the correct sequence to obtain a normal salt. (a) NaOH + Na_(2)HPO_(4) rarr Na_(3)PO_(4) + H_(2)O (b) NaOH + H_(3)PO_(4) rarr NaH_(2)PO_(4) + H_(2)O (c) NaOH + NaH_(2)PO_(4) rarr Na_(2)HPO_(4) + H_(2)O
Answer» bca abc cba cab Solution :(i) `NAOH + H_(3)PO_(4) rarr NaH_(2)PO_(4) + H_(2)O` (ii) `NaHO + NaH_(2)PO_(4) rarr Na_(2)HPO_(4) + H_(2)O` (iii) `NaOH + Na_(2)HPO_(4) rarr Na_(3)PO_(4) + H_(2)O`

Discussion

28.	Arrange the compounds in sequence of increasing number of oxygen atoms. (a) Suger(b) Plaster of pairs (c) Starch(d) Glucose
Answer» abdc bdac bcad bcda Solution :(i) PLASTER of Paris (ii) Glucose (III) SUGAR (iv) Starch

Discussion

29.	Arrange the components of air in the increasing order of their presentage by volume. (a) Nitrogen (b) Carbon dioxide ( c) Oxygen (d) Argon
Answer» bdca acdb dcba bacd Solution :(i) CARBON DIOXIDE (II) ARGON (III) Oxygen (iv) Nitogen

Discussion

30.	Arrange statements in sequence of increasing order of heat content. (a) Ice of 10 g mass at 10^(@)C(b) water of 10 gmass at 10^(@)C(c )Ice of 10 g mass at 40^(@)C(d) Water of 10 g mass at 40^(@)C (e) Steam of 10 g mass at 10^(@)C
Answer» acbde edcab abecd abedc Solution :(i) Ice of 10 g mass at `10^(@)C`(II) Ice of 10 g mass at `40^(@)C` (III) WATER of 10 g mass at `10^(@)C`(iv)Water of 10 g mass at `40^(@)C` (v) Steam of 10 g mass at `10^(@)C`

Discussion

31.	Arjun's family stays stays in an area which is in the heart of the city for sake of convenience. During the summer vacation, Arjun's family stays in their farm hous which has all amenities. As the farm house is located in the city outskirts, they could escape from the hot sum in summer. Why is the temperature in the peripheral area relatively lower than that in the heart of the city ?
Answer» Solution :In the interior of CITIES, the density of POPULATION is more, as a result a large volume of traffic exists which leads to and increase in the gaseous contents such as `CO_(2)`, METHANE and nitrous OXIDES which contribute to global warming. Hence the temperature in the interior of the cities is higher than in the OUTSKIRTS of the cities.

Discussion

32.	Aquatic animals are able to survive in water bodies like rivers and oceans during winter when the atmospheric temperature is -10^(@)C. This is because
Answer» density of ice is less than WATER. density of water is minimum at `4^(@)C`. ice is a poor CONDUCTOR of HEAT. both 1 and 3. Solution :Aquatic organisms are able to SURVIVE in lakes during winter even though there is ice at the surface because the density of ice is less than that of water, ice is a poor conductor of heat.

Discussion

33.	Antacid pair among the following is
Answer» `Ma(OH)_(2), NaOH` `Mg(OH)_(2), A1(OH)_(3)` KOH, NaOH `A1(OH)_(3), NaOH` Solution :Antacid is the substance which is USED to neutralize the ACIDITY in STOMACH. Generally, ANTACIDS used are magnesium hydroxide and aluminium hydroxide.

Discussion

34.	An invertad glass jar is placed over a burning candle. After a while, the candle is removed and the inverted glass jar is placed in a through in a trough of water. What do you obseve and justifyyour observetions.
Answer» Solution :BURNING of candle produces `CO_(2)` and water. When the CYLINDER fontaining `CO_(2)` is incerted into water through the `CO_(2)` dissolves in water as a result the water LEVEL slightly reises in the glass jarr. Thus it indicates that `CO_(2)` is soluble in water.

Discussion

35.	An element X on treatment with oxygen gives Y which on hydrolysis produces Z.Z on treatment with higher oxide of carbon 'A' gives milky white precipitate 'B'. Identify X, Y, Z, A and B?
Answer» Solution :As Z on treatment with oxide "A" of carbon GIVES MILKY appearance to the solution by forming. B, Z is `Ca(OH)_(2), A "is" CO_(2), B "is" CaCO_(3)`. As Z is produved by hydrolysis of Y. Y is CAO. As Y is prepared by treating "X" with oxygen, X is Ca. `underset(("X"))(Ca + O_(2)) rarr underset(("Y"))(CaO)` `underset("Y")(CaO) + H_(2)O rarr underset("Z")(Ca(OH)_(2))` `underset("Z")(Ca(OH)_(2)) + underset("A")(CO_(2)) rarr underset("B")(CaCO_(3)) + H_(2)O`

Discussion

36.	An element 'X' is non-malleable and non-ductile. X is extensively used to protect another element Y from corrosion.Identify X and Y and name the process thatis mentioned above. Also compare thereactivity of X and Y.
Answer» SOLUTION :Element X is zinc which is NON -malleable and non-ductile. Y is iron. The process of process of protecting rion by zinc is called galvanization. The element X(Zn) in more REACTIVE than Y (Fe).

Discussion

37.	An element X, in which the difference in electrons present valence shell (M shell) and penultimate shell is equal to the number of electrons present in first shenll, undergoes combustion to produce Y. Y turns lime water milky due to the formaion of Z. Identify X, Y and Z.
Answer» `C, CO_(2),CaCO_(3)` `S,SO_(2),CaSO_(3)` `S, SO_(2),CaSO_(3)` `C,CO_(2),Ca(HCO_(3))_(2)` Solution :Electronic configuration of X is 2, 8, 6 Hence X is SULPHUR `underset((X))(S)+O_(2)tounderset((Y))(SO_(2))` `underset(Y)(SO_(2))+underset(("milky white"))(Ca(OH)_(2))tounderset(Z)(CaSO_(3))darr+H_(2)O`

Discussion

38.	An element 'X', in which the difference in electrons present in valence shell and penultimate shell is equal to the number of electrons present in first shell, undergoes combustion to produce 'Y'. 'Y' turns lime water milky due to theformation of 'Z'.Identify 'X','Y' and'Z'.
Answer» `C,CO_(2),CaCO_(3)` `S,SO_(2),CaSO_(3)` `S,SO_(2),Ca(HSO_(3))_(2)` `C,CO_(2),Ca(HCO_(3))_(2)` Solution :ELECTRONIC confifuration X is of 2, 8, 6. Hence X is sulphur `underset((X))(S+O_(2))tounderset((Y))(SO_(2))` `underset((Y))(SO_(2))+Ca(OH)_(2)tounderset(("MILKY white"))underset((Z))(CaSO_(3)darr+H_(2)O)`

Discussion

39.	An element X burns with a brilliant blue flame in the presence of oxygen ot form Y. Y truns acidified potassium dichromate paper green. Identify X and Y.
Answer» Nitrogen nitrogen dioxide Sulphur, sulphur dioxide Phosphorus, phosphorus pentoxide Sodium, sodium oxide Solution :Sulphur is the non-metal which burns with a blue COLOURED flams. `SO_(2)` TURNS orange coloured `K_(2)Ce_(2)O_(7)` green due to the formation of `CR(SO_(4))_(3)`.

Discussion

40.	An element X burns with a briliant blue flame in the presence of oxygen to form Y.Y turns acidified potassium dichromate paper green. Identigy X and Y.
Answer» Nitrogen, nitrogen dioxide Sulphur, sulphur dioxide Phosphorus, phosphorus pentoxide Sodium, sodium oxide Solution :Sulphur is the NONMETAL which burns with burns with a blue coloured flams. `SO_(2)` turns orange coloured `K_(2)Cr_(2)O_(7)` GREEN due to the formation of `Cr_(2)(SO_(4))_(3)`

Discussion

41.	An element with electronic configuration 2, 8, 1 forms acompound with carbonate. How does this compound remove both temporary and permanent hardness of water?
Answer» Solution :Element with ELECTRONIC configuration 2, 8, 1 is NA and its carbonate is SODIUM carbonate which is called washing soda. It is used for the removal of both temporary and PERMANENT hardness of water. `Ca(HCO_(3))_(2) + Na_(2)CO_(3) rarr CaCO_(3) darr + 2NaHCO_(3)` `CaSO_(4) + Na_(2)CO_(3) rarr CaCO_(3) darr + Na_(2)SO_(4)` `CaCO_(3)` is insoluble and hence settles down. In this way washing soda can be used to remove both temporary and permanent hardness of water.

Discussion

42.	An atom of anelement 'X' has three completely filled shell . Theratio of electrons in 1 and 4 shells is 1:1. Find the atomic number of 'X' . Alsowrite the formulae of its bicarbonate , chromate and phosphide.
Answer» Solution :The electronic arrangement of X must be 2 , 8 , 18 , 2 So the ATOMIC NUMBER of X ahould br 30 . The element X is Zn which can form`Zn^(+2)`ion by LOSING 2 electrons from N shell.

Discussion

43.	An atom of an element has two shells with electrons . Thevalence shell has 2n+1electrons where nis the number of electrons in the inner shell . Thiselement can form a radical 'X' with hydrogen and two radicals Y and Z with oxygen, Z has more number of oxygen than Y. identifythe element and the radicals. write the reaction taking place between solutions of two salts , AgZ and XCl . Identify the type of reaction.
Answer» Solution :K shell can have only 2 electrons. That means n=2 and the number of electrons in L shell is 2n+1 which is equal to 5. The electronic arrangement that is 2,5 corresponds to nitrogen. Nitrogen can form `NH_(4)^(+)`with hydrogen. Y is `NO_(2)^(-)and Z" is " NO_(3)^(-)`. `AgNO_(3)+NH_(4)Cl toNH_(4)NO_(3)` This is a double DECOMPOSITION reaction where silver chloride being insoluble settles at the bottom. Therefore, this is a PRECIPITATION reaction.

Discussion

44.	An atom of an element hasthe electrons distributedin four shells . If the electrons present in I and IV shells is in1:1ration and , the ratio of electrons in II and IIIshell is also1:1, predict its valency and justofy .Write the formulaeof (a) nitride (b) silicate (c ) chloride.
Answer» Solution :`{:(K,L_(,),M,N),(2_(,),8,8,2):}` Hence the valency of an ATOM of an element (M) with above electronic CONFIGURATION is 2 andby losing twoelectrons it attains octetconfiguration. (a)Formula of its nitride is`M^(+2)N^(-3)toM_(3)N_(3)` (b)Formula of its silicate is`M^(+2)SiO3^(-2)toMSiO_(3)` ( C)Formula of its chloride is `M^(+2)Cl^(-)toMCl_(2)`

Discussion

45.	An atom is electrically neutral . Justify.
Answer» Solution :In an atom , the number of electrons is EQUAL to the number of protons INSIDE the nucleus . SINCE the protons and electrons carry equal and oppositecharges , an atom is electriclly NEUTRAL.

Discussion

46.	An atom is electrically neutral .
Answer» Solution :True An atom is ELECTRICALLY NEUTRAL due to the PRESENCEOF EQUAL NUMBER of positively and negatively charged particles.

Discussion

47.	An apartment owner called for a plumberto replace one of the leaking pipe lines. The plumber arrived andfound that the galvanized iron pipes are deteriorated andcorroded. He advised theapartment owner to replace the galvanized iron pipes with the PVCpipes. Why did the plumber give the above suggestion?
Answer» Solution :PVC pipes are polyvinyl chloride pipeswhich are thermoplastic in nature and more durable as theyare completely TUST free and less EXPENSIVE than galvanised iron pipes. Though galvanization prevents ruting , since the PIPELINES are in CONTINUOUS contact with water, the coating may GET worn off over a period of time and it may be corroded.

Discussion

48.	Among the noble gases which gas does not have octet configuration?
Answer» Neon HELIUM Argon Xenon Solution :Helium has DUPLET CONFIGURATION.

Discussion

49.	Among the following, which substance turns phenolphthalein pink ?
Answer» SODA water Lime water Commin SALT Sugar solution Solution :Since lime water is BASIC in nature it turns phenolphthalein pink.

Discussion

50.	Among the following which is a pair of soft metals ?
Answer» SODIUM, POTASSIUM Potassium, magnesium Magnesium, calcium Calcium, manganese Solution :SOFT METALS are sodium, potassium

Discussion

Explore topic-wise InterviewSolutions in Current Affairs.

Arrange the steps in a sequence for the removal of microorganisms during the purification of drinking water. (a) Lime feeder(b) Mechanical mixing(c ) Alum feeder(d) Sedimentation tank(e) Passing through gravel and sand (f) Chlorine feeder

Arrange the steps in a sequence for the conversion of atmospheric water vapour into underground water. (a) Infiltration in recharge area (b) Water table (c ) Infiltration in zone of aeration (d) Precipitation(e) Aquifer

Arrange the steps in a sequence for the formation of rainfall.(a) Formation of micelles(b) Condensation(c ) Evaporation(d) Formation of clouds (e) Precipitation

Arrange the staps in sequence for the manufacture fo glass.

Arrange the process in sequence for the purification of drinking water (a) Lime feeder, alum feeder(b) Filtration(c ) Mechanical mixing(d) Chlorination

Arrange the relevant steps in correct sequence for themanufacture of sodium chloride from sea water. (a) Making of hot saturated solution (b) Evaporation (c) Recrystallization (d) Collection of sea water (e ) Addition of small quantity of sodium iodide or potassium iodide

Arrange the layers of the atmosphere as per the following terms related in a sequence order respectively. Inversion layer, convertion currents, absorbs harmful radiations and burning up of meteorites (a) Troposphere (b) Stratophere ( c) Exophere (d) Mesosphere (e ) Ionophere

Arrange the given compounds inthe increasing order of carbon atoms present in the compounds (a) Methane (b) Suger (c) Glucose (d) Starch

Arrange the general steps for the purification of water in a sequence. (a) Filtration(b) Chlorination (c ) Sedimentation (d) Addition of chemicals

Arrange the following terms in sequence from source to supply. (a) Chlorination (b) Sedimentation (c ) Filtration(d) Storage water tank (e) Lakes

Arrange the following substance in the ascending order of the number of constituent element(s) present in them. (a) Sodium bicarbonate, (b) Calcium carbonate ( c) Water, (d) Copper

Arrange the following layers of the atmophere in the decreasing order of their altitudes. (a) Stratosphere (b) Troposphere ( c)Mesophere (d) Exosphere ( e) Ionophere

Arrange the following given reactions in a sequence for the process of nitrogen fixation. (A) Formation of metal nitrates (B) Formation of nitrogen doxide. ( C) Formation of itric oxide (D) Formation of nitric acid

Arrange the following equations in the correct sequence to obtain a normal salt. (a) A1(OH)C1_(2) + HCI rarr A1C1_(3) + H_(2)O (b) A1(OH)_(3) + HC1 rarr A1(OH)_(2)C1 + H_(2)O (c) A1(OH)_(2)C1 + HC1 rarr A1(OH)C1_(2) + H_(2)O

Arrange the following examples in the oredr of matter, compound, element and mixture. (a) Dilute acid, (b) Argon (c ) Water, (d) Ball

Arrange the following equations in the correct sequence to obtain a normal salt. (a) NaOH + Na_(2)HPO_(4) rarr Na_(3)PO_(4) + H_(2)O (b) NaOH + H_(3)PO_(4) rarr NaH_(2)PO_(4) + H_(2)O (c) NaOH + NaH_(2)PO_(4) rarr Na_(2)HPO_(4) + H_(2)O

Arrange the compounds in sequence of increasing number of oxygen atoms. (a) Suger(b) Plaster of pairs (c) Starch(d) Glucose

Arrange the components of air in the increasing order of their presentage by volume. (a) Nitrogen (b) Carbon dioxide ( c) Oxygen (d) Argon

Arrange statements in sequence of increasing order of heat content. (a) Ice of 10 g mass at 10^(@)C(b) water of 10 gmass at 10^(@)C(c )Ice of 10 g mass at 40^(@)C(d) Water of 10 g mass at 40^(@)C (e) Steam of 10 g mass at 10^(@)C

Aquatic animals are able to survive in water bodies like rivers and oceans during winter when the atmospheric temperature is -10^(@)C. This is because

Antacid pair among the following is

An invertad glass jar is placed over a burning candle. After a while, the candle is removed and the inverted glass jar is placed in a through in a trough of water. What do you obseve and justifyyour observetions.

An element X on treatment with oxygen gives Y which on hydrolysis produces Z.Z on treatment with higher oxide of carbon 'A' gives milky white precipitate 'B'. Identify X, Y, Z, A and B?

An element 'X' is non-malleable and non-ductile. X is extensively used to protect another element Y from corrosion.Identify X and Y and name the process thatis mentioned above. Also compare thereactivity of X and Y.

An element X, in which the difference in electrons present valence shell (M shell) and penultimate shell is equal to the number of electrons present in first shenll, undergoes combustion to produce Y. Y turns lime water milky due to the formaion of Z. Identify X, Y and Z.

An element 'X', in which the difference in electrons present in valence shell and penultimate shell is equal to the number of electrons present in first shell, undergoes combustion to produce 'Y'. 'Y' turns lime water milky due to theformation of 'Z'.Identify 'X','Y' and'Z'.

An element X burns with a brilliant blue flame in the presence of oxygen ot form Y. Y truns acidified potassium dichromate paper green. Identify X and Y.

An element X burns with a briliant blue flame in the presence of oxygen to form Y.Y turns acidified potassium dichromate paper green. Identigy X and Y.

An element with electronic configuration 2, 8, 1 forms acompound with carbonate. How does this compound remove both temporary and permanent hardness of water?

An atom of anelement 'X' has three completely filled shell . Theratio of electrons in 1 and 4 shells is 1:1. Find the atomic number of 'X' . Alsowrite the formulae of its bicarbonate , chromate and phosphide.

An atom of an element hasthe electrons distributedin four shells . If the electrons present in I and IV shells is in1:1ration and , the ratio of electrons in II and IIIshell is also1:1, predict its valency and justofy .Write the formulaeof (a) nitride (b) silicate (c ) chloride.

An atom is electrically neutral . Justify.

An atom is electrically neutral .

Among the noble gases which gas does not have octet configuration?

Among the following, which substance turns phenolphthalein pink ?

Among the following which is a pair of soft metals ?