Selina Concise Class 7 Chemistry Solution Chapter No. 6- ‘Metals and Non metals’ For ICSE Board Students.
1)
a)
Answer : Gold
b)
Answer : Zinc
c)
Answer : platinum
d)
Answer : Sodium
e)
Answer : Copper
f)
Answer : Mercury
g)
Answer : Silver
2)
a)
Answer : Graphite
b)
Answer : Diamond
c)
Answer : Chlorine
d)
Answer : Iodine
e)
Answer : Argon ( Ar)
f)
Answer : Random (Rn)
g)
Answer : Bromine
3)
a)
Answer : Iron :
- Iron used for making vehicle like bike , truck , car etc.
- Iron used in making building materials like iron rod , windows , pipe , iron nails , etc.
- Approximately 98% of iron ore is to make steel .
b)
Answer : Aluminium :
- Aluminium metal used in manufacturing of wire and electrical appliances .
- Aluminium used in construction of air craft , lightweight vehicle , ladder , drink cane and roofing materials .
- Aluminium also used in Manufacture of utensils .
c)
Answer : Gold :
- Gold is used to making jewellery .
- Gold is used in space to reflect radiation and stabilized temperature .
- Gold is also used as fake teeth to elderly because it is chemically not reactive . Gold teeth allow you to eat without getting any poisonous effect or reaction.
d)
Answer : Oxygen :
- Oxygen is essential for all living organisms ( human and animals) for breathing and respiration .
- Oxygen used in oxidising agent to oxidising oil.
- Oxygen used in medicine .
e)
Answer : Iodine :
- Iodine is used to treat and prevent iodine deficiency .
- Iodine used as an antiseptic .
- Iodine used for boost thyroid health.
4)
a)
Answer : Magnesium is used in fireworks because , magnesium burn with bright white light .
b)
Answer : Aluminium is used in making aircraft because , aluminium metal is lightweight and strong .
c)
Answer : Copper is used in making electric cable because , copper is good conductor of electricity and highly ductile.
d)
Answer : Graphite is used in lead of pencil because , graphite has black colour carbon substance , and it is very soft and slippery.
e)
Answer : Impure Diamond is used to cut glass because , it is hardest naturally occurring substance .
f)
Answer : Gold is mixed with copper and nickel because , Gold is the most malleable metal and very soft , when gold mixed with small quantity of copper and nickel it becomes hard for making jewellery .
g)
Answer : Tungsten is used in electric bulb because Tungsten metal have highest melting point .
5)
a)
Answer : Brass :
Brass alloys have Copper and Zinc metals
b)
Answer : Bronze :
Bronze alloys have Copper and tin metals.
c)
Answer : Duralumin :
Duralumin alloys have Aluminium and copper metals .
d)
Answer : stainless steel :
Stainless steel alloys Iron, chromium , nickel , metals .
6)
Answer :
Reference/ Properties | Metal | Non -Metal |
a) Melting and boiling point | Metals have high boiling point and high melting point. | Non metals have low boiling point and low melting point |
b) Conductivity of heat and electricity | Metals are good conductor of heat and electricity. | Non metals are poor conductor of heat and electricity (except graphite ) |
c) Malleability | Metals are malleable . | Non-Metals are non malleable . |
d) Solubility in water | Metals are not soluble in water. | Some non metals are soluble in water while some non metals are not soluble in water. |
Answer : Metalloid :
Those elements which have intermediate properties between metals and non metals or show some properties of metal and some properties of Non-metals are known as Metalloid .
Example : Silicon, Germanium , Arsenic , Tellurium , Antimony etc.
8)
a)
Answer : Silicon :
- Silicon used in the production of fire bricks .
- Silicon used in glass , steal production and computer chips .
- Being semiconductor , silicon is put into use for making transistor.
b)
Answer : Antimony :
- Antimony alloyed with lead to harden it ,its used for lead acid batteries ,and bullet
- Antimony used for making solar panel , LED , OLED , screen .
- Antimony used for production of ceramic and glass
c)
Answer : Tungsten :
- Tungsten used in manufacture of missile , due to high temperature application.
- Tungsten used in winding and heating element for electrical furnace .
- Tungsten trioxide used in making Infrared switching device , high density memory device , smart windows etc.
d)
Answer : Germanium :
- Germanium used in infrared spectroscope and other optical equipment.
- Germanium used in wide angle camera lenses , and microscopic objectives.
- Germanium used to make transistor for use in electronics device.
OBJECTIVE TYPE QUESTIONS
1)
a) The most ductile metal is ……………
Answer : Gold
(ductility means stretching , and pulling a metal into a thin wire without break down , so most ductile metal is gold , silver platinum copper etc)
b) A metal stored kerosene oil is …………..
Answer : Sodium
(Sodium metal does not kept in open air because it react with oxygen and produce sodium oxide which highly reactive and catch fire easily that is why sodium metal kept in a kerosene oil , kerosene oil does not react with sodium.)
c) Tungsten metal is good conductor of…………..
Answer : heat
( Tungsten is good conductor of heat because it has high melting point and high resistivity towards heat)
d) ……………is a soft metal .
Answer : pure gold
(Pure Gold is a soft metal because gold atom arrange loosely bond or loose metallic bond each other and have less force of attraction between gold atom due this pure gold is soft metal)
e) ………………is the hardest compound known to us.
Answer : Silicon carbide
(Silicon carbide is hardest compound known us because it has tetrahedral shape four carbon bond strongly attached with silicon bond that properties make this compound hard )
f) A non metal used to purify water is ……………
Answer : Chlorine
(Chlorine is a non metal kill germs , and microorganisms from water , so it is used for purification of water )
g) A metal that gives dazzling effect to crackers when they explode is …………..
Answer : Magnesium
(Magnesium burns with bright white light or give dazzling effect when it burn that is why Magnesium used in crackers)
h) A chemical compound that make up the striking heads of matchstick is ………….
Answer : Phosphorus sulphide
(Phosphorus sulphide is a chemical that make up the striking heads of matchstick because of the friction on the ignition surface , red phosphorus on the friction surface convert into white phosphorus and heat ignites the phosphorus .)
2)
Answer :
Column A | Column B |
a) Helium | 4.) Weather observation balloons |
b) Neon | 5) Advertising signboard |
c) Argon | 1) Electric bulb |
d) Germanium | 3) Semiconductor |
e) Mercury | 2) Thermometer |
3)
a)
Answer : False
b)
Answer : True
c)
Answer : True
d)
Answer : False
e)
Answer : True.
MULTIPLE CHOICE QUESTIONS
1)
Answer : b) Neon
(Neon gas used in advertising signboard because when light is pass through Neon gas it
2)
Answer : a) Gallium
(Gallium is the metal which has less than 50°C melting point)
3)
Answer : c) Zinc
( Zinc is a metal which has property hard and brittle , which is neither ductile nor malleable)
4)
Answer : a) Radish brown
(Iron of rust is radish brown in colour which is hydrated oxide form by the reaction of iron and oxygen in presence of water or air moisture)
5)
Answer : c) fireworks
(Aluminium is not used to make fireworks because aluminium is highly hazardous materials due to its sensitivity and reactivity)
6)
Answer : c) Silicon
(Silicon is a non metal used to Manufacture of computer microchips , transistor , fire bricks etc.)
7)
Answer : d) antimony .
(Antimony is a Metalloids used to make glass , flame proofing material , paint , ceramic etc)