Question 1

Question 3Mention two uses of the following metals and non-metals:(a) Iron(b) Aluminium(c) Gold(d) Oxygen(e) Iodine

Accepted Answer

(a) Iron is used for:Construction of power transmission towers.Making pipes, tanks, cylinders, nails, agricultural tools, railings, wire meshes etc.(b) Aluminium is used for:Making utensils, cans for drinks, furniture, window frames etc.Packaging foodstuffs and wrappers of medicines in the form of aluminium foil.(c) Gold is used for:Making jewellery and gold coins.In dentistry to fill in teeth cavities(in form of alloy with silver).(d) Oxygen is used for:Breathing and respiration, in hospitals oxygen cylinders are used for serious patients to help them in breathing.It is essential for combustion.(e) Iodine is used for:Making photographic films in the form of potassium iodide.Making tincture of iodine and iodex which are used as an antiseptic and pain reliever respectively.

Question 2

Question 6Give four differences between metals and non-metals with reference to their:(a) Melting point and boiling point(b) Conductivity of heat and electricity(c) Malleability(d) Solubility in water.

Accepted Answer

(a) Metals have high melting point and boiling point whereas non-metals have low melting point and boiling point.(b) Metals are good conductors of heat and electricity but non-metals are bad conductors of heat and electricity.(c) Metals are mostly malleable while non-metals are not malleable.(d) Metals are insoluble in water while non-metals can be soluble or insoluble in water.

Question 3

Question 1Give the common name and chemical name of an ore of –(a) zinc(b) Aluminium(c) iron

Accepted Answer

The common name and chemical name of ores of following elements are:S.No.MetalCommon NameChemical Name(a)ZincZinc blendeZinc sulphide [ZnS](b)AluminiumBauxiteAluminium oxide [Al2O3.2H2O](c)IronHaematiteIron [III] oxide [Fe2O3]

Question 4

Question 2Distinguish between the physical properties of metals and non-metals with reference to —(a) lustre(b) malleability(c) ductility(d) tensile strength(e) sonority(f) conduction of heat and electricity(g) melting and boiling point(h) density

Accepted Answer

S.No.PropertiesMetalsNon-metals(a)LustreShows brightnessShows no brightness(b)MalleabilityCan be beaten into sheetsCannot be beaten into sheets.(c)DuctilityCan be drawn into wiresCannot be drawn into wires.(d)Tensile strengthHave high tensile strengthHave low tensile strength(e)SonorityProduce sound when struckDo not produce sound when struck(f)Conduction of heat and electricityCan conduct heat and electricityPoor or non-conductors of heat and electricity(g)Melting and boiling pointHave high melting and boiling pointHave low melting and boiling point(h)DensityHave high densityHave low density

Question 5

Question 4With reference to the following metals state their – use in daily lifeMetals:(a) copper(b) iron(c) aluminium(d) magnesium(e) zinc(f) lead(g) silver

Accepted Answer

(a) Copper is used in :making electrical cablesmaking utensils(b) Iron is used in :construction of bridgesmaking utensils, surgical instruments (in the form of stainless steel)(c) Aluminium is used in :making utensilspackaging(d) Magnesium is used in :fireworksfor making alloys called magnalium and duralumin.(e) Zinc is used in :galvanizationdry cells.(f) Lead is used in:flexible pipestips of bullets(e) Silver is used in :making jewellery and coinsmaking thin sheets to decorate sweets

Question 6

Question 5Describe a simple experiment to prove that – a copper wire conducts electricity, but a piece of coal does not.

Accepted Answer

Experiment to prove that a copper wire conducts electricity.Procedure — Join a wire with the battery, copper and bulbObservation — The bulb glows when current passes through the circuit.Conclusion — Copper conducts electricity, hence it is a good conductor of electricity.Experiment to prove that coal does not conduct electricity.Procedure — Join a wire with battery, coal and bulbObservation — The bulb does not glow.Conclusion — Coal does not conduct electricity hence, it is a bad conductor of electricity.

Question 7

Question 6Differentiate between metals and non-metals with reference to –(a) number of electrons in outer or valence shell(b) formation of cation and anion(c) reaction with dilute acids

Accepted Answer

S.No.Chemical PropertyMetalsNon-metals(a)No.of electrons in outer shellMetals have 1, 2 or 3 electrons in the outer or valence shell.Non-metals have 4, 5, 6 or 7 electrons in the outer or valence shell.(b)Formation of cation and anionMetals lose or donate valence electrons and form cations.Non-metals accept valence electrons and form anions.(c)Reaction with acidsMetals react with dilute acids to give hydrogen gas.Non-metals do not react with dilute acids to give hydrogen gas.

Question 8

Question 7Give a reason why – properties of metals are related to their activity or reactivity series of metals. Explain the same with reference to potassium and iron in the series.

Accepted Answer

Activity series of metals is a series of arrangement of metals in order of their reactivity. The most active metal is at the top of the series & the least active metal is at the bottom of the series.Potassium is at the top of the series, hence it is the most reactive metal. It reacts vigorously even with cold water and explosively with acids to liberate hydrogen gas.Iron lies in the middle of the series at number 7, hence it is moderately reactive. It does not react with cold water but reacts smoothly with steam and less vigorously with acids to liberate hydrogen gas.

Question 9

Question 8Give the basic demarcation of the Modern Periodic Table into metals, metalloid and non-metals with special reference to halogens and noble gases.

Accepted Answer

In the Modern Periodic Table:Strong metals are in the extreme left, weak metals are in the middle.Metalloids are in the middle right.Non-metals are to the right in the upper right hand corner.Halogens are present in Group 17 which is the second last group of the periodic table.Noble gases are present in Group 18 which is the last group of the periodic table.

Question 10

Question 9Give a reason why the non-metals – halogens and noble gases are placed in separate groups of the periodic table with special reference to their properties and uses.

Accepted Answer

Reasons for keeping halogens and noble gases in separate groups of the periodic table with special reference to their properties and uses are:Halogens are highly reactive non-metals. They readily react with metals to form salts. On the other hand, noble gases are inert or inactive due to their stable electronic configuration.Halogens typically exist as diatomic molecules whereas noble gases are monoatomic.The reactivity of halogens make them useful in variety of applications like disinfectants (chlorine), pharmaceuticals (iodine) and as non-stick coatings (fluorine derivatives), etc. The inert nature of noble gases makes them useful in neon signs (neon gas), weather balloons & cryogenics (helium), anesthesia (xenon), etc.

Question 11

Question 10State what are metalloids. Name the elements recognized as metalloids. Compare the properties of metalloids with those of metals. State the uses of three different metalloids.

Accepted Answer

Metalloids are elements that show the properties of both metals and non-metals. They have physical and chemical properties, intermediate between those of metals and non-metals.Elements like Boron [B], Silicon [Si], Germanium [Ge], Arsenic [As], Antimony [Sb], Tellurium [Te] are recognized as metalloids.Comparison of properties:PropertyMetalMetalloidsStateSolids at room temperatureSolids at room temperatureNatureGenerally, hard in nature.Brittle in nature.ConductivityGood conductors of heat and electricity.Semi conductors of electricity and show average transmission of heat.LustreShow brightnessShow brightnessMalleability & DuctilityMalleable and DuctileGenerally malleable and DuctileUse of metalloids:Boron — is used as an insecticide and a fire retardant.Arsenic — is used for certain medicinal purposes.Silicon — Silicon gel is generally applied to burn patients and to absorb moisture.

Question 12

Question 11Explain the term – rusting and give a word equation for the formation of rust. If polished iron nails are kept in three separate test tubes, state the contents in each test tube required, to prove the conditions for rusting.

Accepted Answer

Rusting involves slow oxidation of iron in presence of air and moisture resulting in formation of hydrated iron [III] oxide called rust.Iron + Oxygen ⟶ Iron [III] Oxide →moisture\xrightarrow{	ext{moisture}}moisture​ Hydrated Iron [III] Oxide [rust] Test Tube ATest Tube BTest Tube CContentsAnhydrous calcium chlorideBoiled tap water with oil layer on topOrdinary tap waterCondition presentOxygenMoistureMoisture & oxygenCondition absentMoistureOxygenNilResultIron nails do not rustIron nails do not rustIron nails rustConclusionMoisture is essential for rustingOxygen is essential for rustingMoisture and oxygen both are essential for rusting

Question 13

Question 13Give a reason why oiling or greasing is done on the exposed moving iron parts of machinery and not preferred on heavy stationary iron parts.

Accepted Answer

Oiling or greasing is done on the exposed moving iron parts of machinery as it forms a coating which protects it from rusting. It smoothens the surface and reduces friction in the machinery which is its added advantage.Being stationary, for heavy iron parts, red lead oxide paint is used as there is no use of reducing the friction.

Question 14

Question 14State why galvanization, tinning and chromeplating are used as three different processes for coating specific articles for prevention of rusting.

Accepted Answer

Galvanization, tinning and chromeplating are used as three different processes because:In galvanization, iron sheets are dipped in molten zinc. Zinc being more active than iron, protects iron by forming zinc ions more readily. It is used for iron articles exposed to heavy moisture like roof sheds, buckets, tubs, etc.In tinning, iron sheets are dipped in molten tin. It is used for edible applications instead of galvanization because zinc dissolves in food acids and makes poisonous compounds.In chromeplating, iron articles are electroplated with chromium, nickle, tin, copper etc. It is used for decorative purposes. It is costly and used exclusively.Hence, the three processes are different ways of preventing articles from rusting depending on their use.

Question 15

Question 15Give a reason why –(a) rust turns moist red litmus blue(b) a green deposit is seen on the surface of an article of copper(c) iron objects rust easily but the iron pillar at Qutab Minar has not rusted over the years.

Accepted Answer

(a) Rust is hydrated iron [III] oxide. As all metallic oxides are basic in nature and rust is a metallic oxide of iron, hence, it turns moist red litmus blue.(b) The green deposit on copper articles is caused by copper reacting with moisture and atmospheric gases to form copper carbonate [CuCO3], which is green, and copper hydroxide [Cu(OH)2].(c) Iron pillar of Qutab Minar has not rusted over the years becauseThe high purity and great mass of iron may have created a temperature stabilizer thus reducing the condensation of moisture on it.The protective passive iron coating formation on the surface of iron.Good forge welding and absence of impurities in iron.

Question 16

Question 16State a specific reason for using –(a) steel in automobiles(b) gold in jewellery(c) copper in electrical cables(d) zinc in galvanizing(e) lead in bullets(f) magnesium in fireworks.

Accepted Answer

(a) Steel in automobiles — It is malleable with high tensile strength.(b) Gold in jewellery — It is expensive, lustrous, malleable and ductile.(c) Copper in electrical cables — It is a good conductor of electricity.(d) Zinc in galvanizing — It prevents rusting.(e) Lead in bullets — It has high specific gravity.(f) Magnesium in fireworks — It burns with a dazzling light.

Metals and Non-metals

Exercise

Metals and Non-metals