Class 10 - Chemistry - Metals and Non Metals
Which of the following pairs will give displacement reactions?
(a) NaCl solution and copper metal
(b) MgCl2 solution and aluminium metal
(c) FeSO4 solution and silver metal
(d) AgNO3 solution and copper metal.
Correct Option: - (d) AgNO3 solution and copper metal.
As Copper, is more reactive than silver, therefore it displaces silver from silver nitrate solution.
Whereas in all other reactions no displacement reaction will take place as Cu is less reactive than Na,
Al is less reactive than Mg and Fe is less reactive than Ag.
Which of the following methods is suitable for preventing an iron frying pan from rusting?
(a) Applying grease
(b) Applying paint
(c) Applying a coating of zinc
(d) All of the above.
Correct Option: - (c) Applying a coating of zinc
In case of iron frying pan, grease and paint cannot be applied as when the pan will get heated the coating of paint or grease will get washed away.
Therefore coating of zinc is applied.
An element reacts with oxygen to give a compound with a high melting point. This compound is also soluble in water.
The element is likely to be
Correct Option: - (a) Calcium.
Calcium reacts with oxygen to give calcium oxide which is dissolved in water to give lime water.
Food cans are coated with tin and not with zinc because
(a) zinc is costlier than tin.
(b) zinc has a higher melting point than tin.
(c) zinc is more reactive than tin.
(d) zinc is less reactive than tin.
Correct Option: - (c) zinc is more reactive than tin.
Zinc is more reactive than tin therefore food cans are coated with tin and not zinc.
You are given a hammer, a battery, a bulb, wires and a switch.
(a) How could you use them to distinguish between samples of metals and non-metals?
(b) Assess the usefulness of these tests in distinguishing between metals and non-metals.
With the help of bulb, wires, switch and a battery we can test whether they are metals or non-metals as metals will good conductors of electricity and non-metals don’t.
For example: - Graphite is a non- metal but still good conductor of electricity.
What are amphoteric oxides? Give two examples of amphoteric oxides.
The metallic oxides which behave as both acidic and basic oxides are known as amphoteric oxides.
They react with both acids and bases, to form salts and water respectively.
For example: - Aluminium oxide reacts in the following manner with acids and bases –
Al2O3 + 6HCl → 2AlCl3 + 3H2O [Basic]
Al2O3 + 2NaOH → 2NaAlO2 + H2O [Acidic]
Name two metals which will displace hydrogen from dilute acids, and two metals which will not.
Metals which are more reactive than hydrogen will displace hydrogen from dilute acids.
For example: sodium, zinc, iron and potassium.
Metals those are less reactive than hydrogen cannot displace it from the dilute acids.
For example: copper and silver.
In the electrolytic refining of a metal M, what would you take as the anode, the cathode and the electrolyte?
In the electrolytic refining, the impure metal (M) is made the anode, pure metal (M) is made as
cathode and the electrolyte will be aqueous solution of the salt of the metal.
Pratyush took sulphur powder on a spatula and heated it. He collected the gas evolved by inverting a test tube over it, as shown in figure below.
(a) What will be the action of gas on?
(i) dry litmus paper?
(ii) moist litmus paper?
(b)Write a balanced chemical equation for the reaction taking place.
SO2 (g) + H2O (l) → H2SO3 (aq)
State two ways to prevent the rusting of iron
The two ways to prevent the rusting of iron are as follows:-
What type of oxides is formed when non-metals combine with oxygen?
Non-metals combine with oxygen to form acidic oxides.
S(s) + O2 (g) → SO2 (g)
Acidic in nature
(a) Platinum, gold and silver are used to make jewellery.
(b) Sodium, potassium and lithium are stored under oil.
(c) Aluminium is a highly reactive metal, yet it is used to make utensils for cooking.
(d) Carbonate and sulphide ores are usually converted into oxides during the process of extraction.
They won’t react with oxygen because of which they won’t lose their lustre for a very long time.
As a result they are used in jewellery.
You must have seen tarnished copper vessels being cleaned with lemon or tamarind juice.
Explain why these sour substances are effective in cleaning the vessels.
Copper reacts with water, carbon dioxide and oxygen present in the atmosphere to form green coating of copper carbonate on its surface.
This is called tarnishing of copper.
2Cu+ H2O +CO2 + O2à Cu (OH) 2 .CuCO3
The citric acid present in the lemon or tamarind neutralises the basis copper carbonate and dissolves the layer.
That is why; tarnished copper vessels are cleaned with lemon or tamarind juice to give the surface of the copper vessel its characteristic lustre.
Differentiate between metal and non-metal on the basis of their chemical properties.
1. Oxides are basic in nature.
4Na + O2 → 2Na2 O
1. Oxides are acidic or neutral in nature.
C + O2 à CO2
2. Active metals react with dilute acids to liberate hydrogen gas.
2Na + 2HCl → 2NaCl + H2 ↑
2. Non- metals don’t react with acids.
3. They form ionic compounds.
3. They form ionic and covalent compounds.
4. Metals tend to lose electrons to form cations. Therefore they are electropositive.
4. They gain electrons to form anions. So they are electronegative.
5. They react with water to form oxides and hydroxides. Some metals react with cold water, some with hot water, and some with steam.
2Na + 2H2O → 2NaOH + H2 ↑
5. They do not react with water.
A man went door to door posing as a goldsmith. He promised to bring back the glitter of old and dull gold ornaments.
An unsuspecting lady gave a set of gold bangles to him which he dipped in a particular solution.
The bangles sparkled like new but their weight was reduced drastically. The lady was upset but after a futile argument the man beat a hasty retreat.
Can you play the detective to find out the nature of the solution he had used?
He must have dipped the gold metal in the solution of aqua regia − a 3:1 mixture of conc. HCl and conc. HNO3.
Aqua regia is a fuming, highly corrosive liquid. It dissolves gold in it.
After dipping the gold ornaments in aqua regia, the outer layer of gold gets dissolved and the inner shiny layer appears.
That is why the weight of gold ornament reduced.
Give reasons why copper is used to make hot water tanks and not steel (an alloy of iron).
Copper does not react with cold water, hot water, or steam. However, iron reacts with steam.
If the hot water tanks are made of steel (an alloy of iron), then iron would react vigorously with the steam formed from hot water.
3Fe + 4H 2O → Fe3O4 + 4H2
Iron Steam Iron Oxide Hydrogen
That is why copper is used to make hot water tanks, and not steel.