Which metal foil is used for packing some of the medicine tablets ?
Name the non-metal which is used :
(a) to convert vegetable oil into vegetable ghee(solid fat).
(b) as a rocket fuel (in liquid form).
(c) to make electrodes of dry cells.
(d) to preserve food materials.
(e) in the vulcanisation of rubber.
Name one property which is characteristic of (a) metals, and (b) non-metals.
(a) Metals are malleable.
(b) Non-metals are non-malleable.
What is meant by “brittleness” ? Which type of elements usually show brittleness : metals or non-metals ?
Brittleness is the property of being brittle i.e. breaking easily.
Non-metals show brittleness.
What will happen if a strip of zinc is immersed in a solution of copper sulphate ?
When a strip of zinc metal is put in copper sulphate solution, then the blue colour of copper sulphate solution fades gradually and red brown coating of copper is deposited on zinc strip.
What will happen if a strip of copper is kept immersed in a solution of silver nitrate (AgN03) ?
When a strip of copper metal is immersed in silver nitrate solution, the solution gradually becomes blue and a shining greyish-white deposit of silver metal is formed on copper strip.
What happens when iron nails are put into copper sulphate solution ?
When iron nails are placed in copper sulphate solution, the blue colour of copper sulphate solution fades gradually and red-brown copper metal is formed.
How would you show that silver is chemically less reactive than copper ?
If a strip of silver metal is kept immersed in copper sulphate solution for some time, then no reaction occurs. This shows that silver is not able to displace copper from copper sulphate solution.
Give reasons for the following :
Blue colour of copper sulphate solution is destroyed when iron filings are added to it.
Blue color of copper sulphate is destroyed because iron displaces copper from copper sulphate solution as iron is more reactive than copper.
Name a non-metal having a very high melting point.
Which property of graphite is utilised in making electrodes ?
Since graphite is a good conductor of electricity, it is used in making electrodes.
Name two non-metals which are both brittle and non-ductile.
Sulphur and phosphorus.
Explain why, the surface of some metals acquires a dull appearance when exposed to air for a long time.
The surface of some metals acquires a dull appearance when exposed to air for a long time because metals form a thin layer of oxides, carbonates or sulphide on their surface by the slow action of various gases present in air.
Complete and balance the following equations :
Fill in the following blanks with suitable words :
(a) Magnesium liberates………………… gas on reacting with hot boiling water.
(b) The white powder formed when magnesium ribbon burns in oxygen is of………………………………..
(c) Ordinary aluminium strips are not attacked by water because of the presence of a layer of………………………………… on the surface of aluminium.
(d) A metal having low melting point is……………………. but a non-metal having very high melting point is………………………
(e) Calcium is a…………….. reactive metal than sodium.
(b) Magnesium oxide.
(c) Aluminium oxide.
(d) Sodium; Diamond.
(a) What is meant by saying that the metals are malleable and ductile ? Explain with examples.
(b) Name two metals which are both malleable and ductile.
(c) Which property of iron metal is utilised in producing iron sheets required for making buckets ?
(d) Which property of copper metal is utilised in making thin wires ?
(a) Metals are malleable i.e. they can be beaten into thin sheets with a hammer.
Metals are ductile i.e. they can be drawn into thin wires.
(b) Aluminium and copper.
Name two metals which react violently with cold water. Write any three observations you would make when such a metal is dropped into water. How would you identify the gas evolved, if any, during the reaction ?
Sodium and potassium metals react violently with cold water.
1. Metal starts moving over the surface of water making a hissing sound.
2. Metal starts reacting with water causing little explosions.
3. Soon the metal catches fire and starts burning.
(a) With the help of examples, describe how metal oxides differ from non-metal oxides.
(b) Which of the following elements would yield : (i) an acidic oxide, (ii) a basic oxide, and (iii) a neutral oxide ?
Na, S, C, K, H
(a)M etal oxides are basic in nature and turn red litmus blue. For example: Magnesium oxide.
Non-metal oxides are acidic or neutral in nature. The acidic oxides turn blue litmus red. For example: Carbon dioxide.
(b) (i) Acidic oxide: S, C
(ii) Basic oxide: Na, K
(iii) Neutral oxide: H
(a) What are amphoteric oxides ? Give two examples of amphoteric oxides.
(b) Choose the acidic oxides, basic oxides and neutral oxides from the following :
Na2O ; CO2 ; CO ; SO2; MgO ; N2O ; H2O.
(c) Which of the following are amphoteric oxides :
MgO, ZnO, P2O3, Al2O3, NO2
(a) Those metal oxides which show basic as well as acidic behavior are known as amphoteric oxides.
Example: Aluminium oxide and zinc oxide.
(b) Acidic oxide – CO2 , CO, SO2 and N2O ; Basic oxide – Na2O , MgO; Neutral oxide – H2O .
(c) ZnO, Al2O3 .
(a) What is the nature of the oxide SO2 ? What happens when it is dissolved in water ? Write the chemical equation of the reaction involved.
(b) What is the nature of the oxide Na2O ? What happens when it is dissolved in water ? Write the chemical equation of the reaction inolved.
(a) SO2 is acidic in nature. When dissolved in water, it produces sulphurous acid.
(b) Na2O is basic in nature. When dissolved in water, it forms an alkali called sodium hydroxide.