AP 9th Class Physical Science 2nd Lesson Important Questions Is Matter Around Us Pure

These AP 9th Class Physics Important Questions 2nd Lesson Is Matter Around Us Pure will help students prepare well for the exams.

AP 9th Class Physical Science 2nd Lesson Is Matter Around Us Pure Important Questions

Class 9 Physical Science Chapter 2 Important Questions – 2 Marks

Question 1.
What are the properties of a heterogeneous mixture? Give examples.
Answer:

1. Heterogeneous mixtures contain physically distinct parts and have non-uniform compositions.
2. Mixtures of sodium chloride and iron filings, salt and sulphur and oil and water are examples of heterogeneous mixtures.

Question 2.
What are homogeneous mixtures ? Give examples.
Answer:

1. A mixture that has a uniform composition throughout is called a homogeneous mixture.
2. Some other examples of such mixtures are :
   i) salt dissolved in water and
   ii) sugar dissolved in water.

Question 3.
What is a solution ? Give examples.
Answer:
A solution is a homogeneous mixture of two or more substances.
Lemonade, soda water, etc., are all examples of solutions.

Question 4.
Jhansi said that solution is always a liquid. Is she correct ? Write a supportive answer.
Answer:

1. Jhansi’s statement is incorrect.
2. A solution can be in the form of solid solutions as well as gaseous solutions.
3. For example : Ornament gold is a solid solution. Air is a gaseous solution.

Question 5.
What is brass ? Is it a solid solution?
Answer:
Brass is a mixture of approximately 30% zinc and 70% copper.
It is a solid solution because it shows the properties of its constituents and can have variable composition.

Question 6.
How do we say a solution is stable ?
Answer:

1. The solute particles cannot be separated from the mixture by the process of filtration.
2. The solute particles do not settle down when left undisturbed, so we can say that a solution is stable.

Question 7.
What is a suspension ? Give example.
Answer:

1. A suspension is a heterogeneous mixture in which the solute particles do not dissolve but remain suspended throughout the bulk of the medium.
2. The mixture of chalk powder and water is an example of a suspension.

Question 8.
Here the light is passed through glass (a) which contains copper sulphate solution and glass (b) with water and milk mixture.

1) Which effect is seen in the glass (b) ?
2) Name the type of mixtures in both glasses.
Answer:
1) Tyndall effect is seen in the glass (b).
2) Glass (a) contains a solution and glass (b) contains a colloidal solution.

Question 9.
What is a Tyndall effect? Who discovered it?
Answer:

1. Scattering of a beam of light by the colloidal solution is called the Tyndall effect.
2. It was discovered by Tyndall, a scientist.

Question 10.
Write the simple physical methods of separation of heterogeneous mixtures.
Answer:
Heterogeneous mixtures can be separated into their respective constituents by simple physical methods like handpicking, sieving and filtration that we use in our day-to-day life.

question 11.
Answer the following:

	Oxygen	Argon	Nitrogen
Boiling Point (°C)	-183	-186	-196

a) Arrange the gases present in air in increasing order of their boiling points.
b) Which gas forms the liquid first as the air is cooled ?
Answer:
a) Nitrogen < Argon < Oxygen
b) Nitrogen.

Question 12.
Give examples of the metals which are liquid in state at room temperature and at slightly above the room temperature.
Answer:

1. Two elements are liquid at room temperature – mercury and bromine.
2. Elements, gallium and caesium become liquid at a temperature slightly above room temperature (303 K).

Question 13.
Which gas will be released when sulphuric acid is added to (i) iron and sulphur mixture (ii) red hot iron and sulphur mixture ?
Answer:

1. If we add sulphuric to iron and sulphur mixture hydrogen gas will be released,
2. If we add sulphuric to red hot iron and sulphur mixture hydrogen sulphide gas will be released.

Question 14.
Define physical and chemical change.
Answer:
Physical change : A change in which no new substance is formed. Ex: Mixing of salt in water.
Chemical change : A change in which new substance is formed. Ex : Milk: to curd.

Question 15.
What is an element ?
Answer:
An element is a form of matter that cannot be broken down by chemical reactions into simpler substances.
Ex : Gold, Silver, Oxygen.

Question 16.
What is a compound ?
Answer:
A compound is a substance composed of two or more elements chemically combined in a fixed ratio.
Ex : Water – H₂O
Carbondioxide – CO₂
Common salt – NaCl

Question 17.
A solution contains 50 g of common salt in 200 g of water. Calculate the concentration in terms of mass by mass percentage of the solution.
Solution:
Mass of solute (salt) = 50 g ; Mass of solvent (water) = 200 g
Mass of solution = Mass of solute + Mass of solvent = 50 g + 200 g = 250 g
Mass percentage of a solution = \(\frac{\text { Mass of solute }}{\text { Mass of solution }}\) × 100 = \(\frac{50}{250}\) = × 100 = 20%

Question 18.
80 ml of Solution contains 20 g of solute. Calculate the concentration in terms of mass by volume percentage of the solution.
Solution:
Mass of sugar (solute) = 20 g.
Volume of solution (sugar solution) = 80 ml.
Mass by volume percentage of a solution = \(\frac{\text { Mass of solute }}{\text { Volume of solution }}\) × 100 = \(\frac{20}{80}\) × 100 = 25%

Question 19.
800 ml of solution contains 20 grams of solute. Calculate the concentration in terms of mass by volume percentage of the solution.
Solution:
Mass of the solute = 20g
Volume of the solution = 800ml
Mass by volume % = \(\frac{\text { Mass of the solute }}{\text { Volume of the solution }}\) × 100
= \(\frac{20}{800}\) × 100 = 2.5%

Question 20.
What is a Homogeneous nrixture and Heterogeneous mixture ?
Answer:
Homogeneous mixture : A mixture that has uniform composition throughout its mass.
Heterogeneous mixture : A mixture that does not have uniform composition throughout its mass.

Question 21.
Name the three types of elements.
Answer:
The three types of elements are

1. Metals
2. Non-metals
3. Metalloids.

Question 22.
Differentiate between true solution and colloids on the basis of particle size and homogeneity.
Answer:
Difference between True Solution and Colloids :

True Solutions	Colloids
i) The particle size of solute is less than 1 nm.	i) The particle size ranges from 1 to 100 nm.
ii) It is homogeneous.	ii) It may appear to be homogeneous but it is heterogeneous.

Question 23.
A solution is prepared by adding 40g of sugar in 100g of water. Calculate the concentration in terms of mass by mass percentage of solution.
Solution:
Mass percentage = mass of solute/mass of solution × 100
= \(\frac{40}{40 + 100}\) × 100 = \(\frac{40}{140}\) × 100 = 28.57
∴ The concentration of mass percentage of solution is 28.57.

Question 24.
A solution contains 50g of sugar in 350g of water. Calculate the concentration of solution in terms of mass by mass percentage of the solution.
Solution:
Mass percentage = mass of solute / mass of solution × 100
= \(\frac{50}{50 + 350}\) × 100 = \(\frac{50}{400}\) × 100 = 12.5%

Question 25.
Define metalloid. Write names of two metalloids.
Answer:

1. Metalloids are the elements which have intermediate properties between metals and non-metals.
2. Boron, silicon and germanium.

Question 26.
Both smoke and fog are called as Aerosols. Identify the. dispersed phase and dispersing medium in each of them.
Answer:
In smoke dispersed phase is solid and dispersing medium is gas. In fog dispersed phase is liquid and dispersing medium is gas.

Question 27.
Lasya mixed sugar and common salt in a pot by mistake, what will be the nature of this mixture ? Write any two observations on the basis of which you would categorise it.
Answer:
Heterogeneous. This mixture will have

1. Physically distinct parts.
2. Non-uniform composition.

Question 28.
Name the only liquid metal and the only liquid non-metal. Mention two gaseous non-metals.
Answer:
Mercury is the only liquid metal and bromine is the only liquid non-metal. Two gaseous non-metals are hydrogen and nitrogen.

Question 29.
Give two reasons to support the statement that CO₂ is a compound and not a mixture.
Answer:

1. Carbon and oxygen are present in a fixed ratio of 3 : 8 by mass in carbon dioxide.
2. The constituents of carbon dioxide cannot be separated by simple physical methods.

Question 30.
A solution contains 60g of common salt in 240g of water. Calculate the concentra¬tion in terms of mass by mass percentage of solution.
Answer:
Concentration of solution = Mass of solute / Mass of solution × 100
Mass of common salt is 60g, Mass of water is 240g.
Mass of solution = 60 + 240 = 300g
Concentration of solution = \(\frac{60}{300}\) × 100 = 20%

Question 31.
Can a homogeneous mixture have a variable composition ? Justify giving an example.
Answer:
Homogeneous mixtures are the mixtures with uniform composition throughout like sugar solution or another.

Is Matter Around Us Pure Class 9 Important Questions – 3 Marks

Question 1.
Beaker A : A mixture of water and crystal of copper sulphate.
Beaker B : A mixture of water and wheat flour.
Beaker C : A mixture of water and milk.
a) Classify the given solutions into a solution, a suspension and a colloidal solution.
b) Which mixture can show the path of a light beam ?
c) Which mixture can give residue after filtering it ?
d) In which mixture particles will settle down when leaving the mixtures undisturbed for a few minutes ?
Answer:
a) Beaker A : a solution
Beaker B : a suspension
Beaker C : a colloidal solution
b) Beaker C
c) Beaker B
d) Beaker B

Question 2.
Write some methods of calculations of the concentration of a solution.
Answer:
There are various ways of expressing the concentration of a solution, but here we will learn only three methods.
i) Mass by mass percentage of a solution = \(\frac{\text { Mass of solute }}{\text { Mass of solution }}\) × 100
ii) Mass by volume percentage of a solution = \(\frac{\text { Mass of solute }}{\text { Volume of solution }}\) × 100
iii) Volume by volume percentage of a solution = \(\frac{\text { Volume of solute }}{\text { Volume of solution }}\) × 100

Question 3.
Write the properties of a Suspension.
Answer:
Properties of a suspension :

• Suspension is a heterogeneous mixture.
• The particles of a suspension can be seen by the naked eye.
• The particles of a suspension scatter a beam of light passing through it and make its path visible.
• The solute particles settle down when a suspension, is left undisturbed, that is, a suspension is unstable. They can be separated from the mixture by the process of filtration. When the particles settle down, the suspension breaks and it does not scatter light anymore.

Question 4.
Ravali took two beakers, one with a mixture of milk mid water and the other with a mixture of sugar and water. No particles were seen in either glass. Can you say that both are true solutions ? Explain.
Answer:

1. Here the mixture of milk and water is a colloidal solution.
2. It is not the true solution.
3. Due to the small size of the colloidal particles, we cannot see them with naked eye.
4. The mixture of sugar and water is a true solution.

Question 5.
What is a colloidal solution ? What are its components ?
Answer:

1. Colloids are heterogeneous mixtures in which the particle size is too small to he seen with the naked eye, but is big enough to scatter light.
2. Eg: A mixture of milk and water.
3. The components of a colloidal solution are the dispersed phase and the dispersion medium.
4. The solute-like component or the dispersed particles in a colloid form the dispersed phase and the component in which the dispersed phase is suspended is known as the dispersing medium.

Question 6.
Distinguish elements and compounds.
Answer:

Elements	Compounds
Cannot be broken down into simpler substances.	Have a fixed composition can be broken down into elements.
For example : Copper, oxygen, iron etc.,	For example: Water, methane, sugar etc.,

Question 7.
Who used the term element at first ? Who defined the term element ?
Answer:

1. Robert Boyle was the first scientist to use the term element in 1661.
2. Antoine Laurent Lavoisier (1743 – 94), a French chemist, was the first to establish an experimentally useful definition of an element.
3. He defined an element as a basic form of matter that cannot be broken down into simpler substances by chemical reactions.

Question 8.
Distinguish between physical and chemical changes.
Answer:

Physical change	Chemical change
Molecular composition does not change in physical change.	Molecular composition changes in chemical change.
It is a temporary change.	It is permanent change.
New substances are not formed.	New substances are formed.
It can be reversed.	It cannot be reversed.
We can get original substances.	We cannot get original substances.

Question 9.
Differentiate between properties of metals and non-metals.
Answer:

Metals	Non-metals
1) Metals are sonorous i.e., they produce sound.	1) Non-metals are non-sonorous as they do not produce any sound.
2) Metals can be drawn into wires i.e., ductile.	2) Non-metals are non-ductile.
3) Metals can be beaten into thin sheets i.e., malleable.	3) Non-metals are fragile.

Important Questions on Is Matter Around Us Pure Class 9 – 5 Marks

Question 1.
‘A homogeneous mixture can have a variable composition.’ Do you agree with it? Justify your answer.
Answer:

1. Yes, I will agree with this statement.
2. Take two beakers with water.
3. Add 1 spatula and 4 spatulas of copper sulphate to both beakers.
4. Stir them.
5. Compare the colour of the solutions of the two beakers.
6. Though both the beakers have obtained copper sulphate solution the intensity of colour of the solutions is different.
7. This shows that a homogeneous mixture can have a variable composition.

Question 2.
Write the properties of a solution.
Answer:
Properties of a Solution :

1. A solution is a homogeneous mixture.
2. The particles of a solution are smaller than 1 nm (10^-9 metres) in diameter. So, they cannot be seen by the naked eye.
3. Because of their very small particle size, they do not scatter a beam of light passing through the solution. So, the path of light is not visible in a solution.
4. The solute particles cannot be separated from the mixture by the process of filtration.
5. The solute particles do not settle down when left undisturbed, that is, a solution is stable.

Question 3.
Write the properties of a colloid.
Answer:
Properties of a colloid :

1. A colloid is a heterogeneous mixture.
2. The size of the particles of a colloid is too small to be individually seen by the naked eye.
3. Colloids are big enough to scatter a beam of light passing through them and make its path visible.
4. They do not settle down when left undisturbed, that is, a colloid is quite stable.
5. They cannot be separated from the mixture by the process of filtration. But, a special technique of separation known as centrifugation, can be used to separate the colloidal particles.

Question 4.
Write the properties of metals.
Answer:
Metals usually show some or all of the following properties:

1. They have a lustre (shine).
2. They have silvery-grey or golden-yellow colour.
3. They conduct heat and electricity.
4. They are ductile (can be drawn into wires).
5. They are malleable (can be hammered into thin sheets).
6. They are sonorous (make a ringing sound when hit).

Question 5.
Write the different types of colloidal solutions with examples.
(OR)
How colloidal solutions are classified? Explain.
Answer:
Colloids are classified according to the state (solid, liquid or gas) of the dispersing medium and the dispersed phase.

Dispersed phase	Dispersing Medium	Type	Example
Liquid	Gas	Aerosol	Fog, clouds, mist
Solid	Gas	Aerosol	Smoke, automobile exhaust
Gas	Liquid	Foam	Shaving cream
Liquid	Liquid	Emulsion	Milk, face cream
Solid	Liquid	Sol	Milk of magnesia, mud
Gas	Solid	Foam	Foam, rubber, sponge, pumice
Liquid	Solid	Gel	Jelly, cheese, butter
Solid	Solid	Solid Sol	Coloured gemstone, milky glass

Question 6.
What is a mixture? How many types of mixtures are there ? Explain.
Answer:
Mixture : A mixture contains more than one substance (element and/ or compound) mixed in any proportion.
Mixtures are two types : They are Homogeneous mixture and heterogeneous mixture.

Homogeneous mixtures :

1. A mixture that has a uniform composition throughout is called a homogeneous mixture.
2. Some other examples of such mixtures are :
   i) salt dissolved in water and
   ii) sugar dissolved in water.

Heterogeneous mixtures :

1. Heterogeneous mixtures contain physically distinct parts and have non-uniform compositions.
2. Mixtures of sodium chloride and iron filings, salt and sulphur and oil and water are examples of heterogeneous mixtures.

Mixtures can also classify into three types : They are
a) Solutions : A solution is a homogeneous mixture of two or more substances. The major component of a solution is called the solvent and the minor is the solute.

b) Colloidal solutions : Colloids are heterogeneous mixtures in which the particle size is too small to be seen with the naked eye, but is big enough to scatter light.

c) Suspensions : Materials that are insoluble in a solvent and have particles that are visible to the naked eye, form a suspension. Asuspension is a heterogeneous mixture.

Question 7.
Compare the properties of solutions, colloidal solutions and suspensions.
Answer:

	Solution	Colloidal solution	Suspension
Size of particles	Less than 1 nm	Between 1nm to 100 nm	Greater than 100 nm
Visibility of particles	Cannot see through naked eye	Cannot see through naked eye	Can see through naked eye
Settling of particles after leaving undisturbed for some time	Particles do not settle down	Particles do not settle down	Particles settle down
Filtering by filter paper	No residue gives	No residue gives	Residue gives
Scattering of light	Doesn’t scatter	Scatters	Scatters
Examples	Sugar in water	Milk in water	Wheat powder in water

Question 8.
In cities, drinking water is supplied from water works. A flow diagram of a typical water works is shown in below figure. From this figure write down the processes involved to get the supply of drinking water to your home from the water works.
Answer:

1. Water is collected from various sources and stored in the reservoir.
2. From there water is sent to the sedimentation tank and the solid waste is treated here.
3. Then the water is sent to the loading tank to remove the suspended impurities.
4. From there the water is sent to the filtration tank.
5. This filtration tank consists of layers/ beds of coarse gravel, gravel and fine sand. Here impurities are filtered completely.
6. Then chlorinate the water to kill the bacteria and supply it to the houses

Question 9.
Write the differences between mixtures and compounds.
Answer:

Mixtures	Compounds
1) Elements or compounds just mix together to form a mixture and no new compound is formed.	1) Elements react to form new compounds.
2) A mixture has a variable composition.	2) The composition of each new substance is always fixed.
3) A mixture shows the properties of the constituent substances.	3) The new substance has totally different properties.
4) The constituents can be separated fairly easily by physical methods.	4) The constituents can be separated only by chemical or electrochemical reactions.

Question 10.
How do you prepare a homogeneous mixture with variable compositions and a heterogeneous mixture ?
Answer:

1. Let us divide the class into groups A, B, C and D.
2. Group A takes a beaker containing 50 ml of water and one spatula full of copper sulphate powder.
3. Group B takes 50 ml of water and two spatula full of copper sulphate powder in a beaker.
4. Groups C and D can take different amounts of copper sulphate and potassium permanganate or common salt (sodium chloride) and mix the given components to form a mixture.
5. Report the observations on the uniformity in colour and texture.
6. Groups A and B have obtained a mixture which has a uniform composition throughout. Such mixtures are called homogeneous mixtures or solutions.
7. Compare the colour of the solutions of the two groups.
8. Though both the groups have obtained copper sulphate solution but the intensity of colour of the solutions is different. This shows, that a homogeneous mixture can have a variable composition.
9. Groups C and D have obtained mixtures, which contain physically distinct parts and have non-uniform compositions. Such mixtures are called heterogeneous mixtures.

Question 11.
How do you prepare a solution, a suspension and a colloidal solution ?
Answer:

1. Let us divide the class into four groups – A, B, C and D.
2. Distribute the following samples to each group :
   • Few crystals of copper sulphate to group A.
   • One spatula full of copper sulphate to group B.
   • Chalk powder or wheat flour to group C.
   • Few drops of milk or ink to group D.
3. 
4. Each group should add the given sample in water and stir properly using a glass rod.
5. Observe visibility of the particles in the mixture.
6. Direct a beam of light from a torch through the beaker containing the mixture and observe from the front.
7. Observe the path of the beam of light.
8. Leave the mixtures undisturbed for a few minutes (and set up the filtration apparatus in the meantime).
9. Observe whether the mixture stable or the particles begin to settle after some time.
10. Filter the mixture. Look for residue on the filter paper.
11. Discuss the results and form an opinion.
12. Groups A and B have got a solution.
13. Group C has got a suspension.
14. Group D has got a colloidal solution.

Question 12.
How do you prepare a saturated and a supersaturated solution ?
Answer:

1. Take approximately 50 ml of water each in two separate beakers.
2. Add salt in one beaker and sugar or barium chloride in the second beaker with continuous stirring.
3. This solution is unsaturated, because some more solute can be dissolved.
4. Now, add more solute.
5. When no more solute can be dissolved, the solution is Said to be saturated.
6. Now, heat the contents of the beaker to raise the temperature by about 5°C.
7. Start adding the solute again.
8. It is a supersaturated solution.

Question 13.
How do you show the difference between a compound and an element through an experiment ?
Answer:

1. Divide the class into two groups.
2. Give 5 g of iron filings and 3 g of sulphur powder in a china dish to both the groups.
   Group I :
3. Mix and crush iron filings and sulphur powder. ,
   Group II :
4. Mix and crush iron filings and sulphur powder.
5. Heat this mixture strongly till red hot. *
6. Remove from flame and let the mixture cool. .
   Group I and II :
7. Check for magnetism in the material obtained.
8. Bring a magnet near the material and check if the material is attracted towards the magnet;
9. Compare the texture and colour of the material obtained by the groups.
10. Add carbon disulphide to one part of the material obtained. Stir well and filter.
11. Add dilute sulphuric acid or dilute hydrochloric acid to the other part of the material obtained.
12. Perform all the above steps with both the elements (iron and sulphur) separately.
13. You must have observed that the products obtained by both the groups show different properties, though the starting materials were the same.
14. Group I has carried out the activity involving a physical change whereas in case of Group II, a chemical change (a chemical reaction) has taken place.
15. The material obtained by group I is a mixture of the two substances.
16. The substances given are the elements – iron and sulphur.
17. The properties of the mixture are the same as that of its constituents.
18. The material obtained by group II is a compound.

Question 14.
Which of the following will show “Tyndall effect” ? How can you demonstrate “Tyndall effect” in them ?
a) Salt solution
b) Milk
c) Copper sulphate solution
d) Starch solution
Answer:
Milk shows Tyndall effect.
Demonstration:

1. Prepare the milk, copper sulphate, salt and starch solutions in different beakers.
2. Allow a beam of light through each of them.
3. The path of the light beam is clearly visible to us through milk.
4. The path of the light beam is not visible through remaining.
5. This experiment will be effective if it is performed in a dark room.

Question 15.
Give some daily life experiences where you can observe “Tyndall effect”. (OR) What is Tyndall effect ? Write any two applications of Tyndall effect.
Answer:
Tyndall effect : Scattering a beam of light is called the”Tyndall effect”.
Daily life experiences:

1. Select a room where the sunlight falls directly through a window.
   Close the window in such a way that a slit is left open between the windows.
   We observe a beam of light passing through the slit.
2. While walking on a road having a lot of trees on both sides, when the sunlight passes through branches and leaves, we can see the path of dust particles.
3. In cinema halls we can observe the beam of light scatters from projector to the screen.
4. When smoke in the kitchen is exposed to sunlight, we can observe the path of smoke particles.

Extra Questions on Is Matter Around Us Pure Class 9 – 4 Marks

Question 1.
Fill the table with suitable answers.

S.No.	Solution	Solvent	Solute
1.	A solution of sugar in water
2.	A solution of iodine in alcohol
3.	Soda water
4.	Air

Answer:

S.No.	Solution	Solvent	Solute
1.	A solution of sugar in water	water	sugar
2.	A solution of iodine in alcohol	alcohol	iodine
3.	Soda water	water	CO2 gas
4.	Air	nitrogen	other gases

Question 2.
Fill in the table with suitable answers.

S.No.	Type of mixture	Particle visible to naked eye (yes/no)	Scattering of light (yes/no)	Residue on filtering (yes/no)	Separate components by physical	Separate components by centrifuge (yes/no)
1.	Solution
2.	Colloidal solution
3.	Suspension

Answer:

S. No.	Type of mixture	Particle is visible to naked eye (yes/no)	Scattering of light (yes/no)	Residue on filtering (yes/no)	Separate components by physical methods (yes/no)	Separate components by centrifuge (yes/no)
1.	Solution	no	no	no	no	no
2.,	Colloidal solution	no	yes	no	no	yes
3.	Suspension	yes	yes	yes	yes	yes

Question 3.
Classify the following substances in the below given table.

Ink, soda water, brass, fog, blood, aerosol sprays, fruit salad, black coffee, oil and water, boot polish, air, nail polish, starch solution, milk.

Answer:

Solution	Suspension	Colloidal .dispersion
Soda water	Ink	Fog
Fruit salad	Nail polish	Aerosol sprays
Black coffee	Starch solution	Boot polish
Air		Milk
Brass		Blood
		Oil and water

Question 4.
The given picture shows the path of sunlight through the canopy of a dense forest.

a) Name the phenomenon.
b) How does it occur ?
Answer:
a) It is a phenomenon of a Tyndall effect.

b) We know that the colloidal solution shows the path of the light beam. The Tyndall effect can be observed when sunlight passes through the canopy of a dense forest. In the forest, mist contains tiny droplets of water, which act as particles of colloid dispersed in the air.

Question 5.
What happens when:
i) Dilute sulphuric acid is added to a mixture of iron filings and sulphur powder.
ii) Dilute sulphuric acid is added to a mixture of iron filings and sulphur powder heated to red hot followed by cooling.
Answer:
i) Fe + H₂SO₄ (aq) → FeSO₄ + H₂
ii) FeS + H₂SO₄ (aq) → FeSO₄ + H₂