Question

1. What is the general name of the materials which contain at least two pure substances

and show the properties of the constituents?

2. Which of the following is a mixture?

Salt, Air, Water, Alum, Sugar

3. Classify the following into elements and compounds:

a. H2O b. He c. Cl2 d. CO e. Co

4. Name the property:

(a) Which allows metals to be hammered into thin sheets.

(b) Which enables metals to be drawn into wires.

5. Which of the following are 'pure substances'?

Ice, Milk, Iron, Hydrochloric acid, Calcium oxide, Mercury, Brick, Wood, Air

6. What is the other name for impure substances? Give two examples of impure

substances.

7. State three reasons why you think air is a mixture and water is a compound.

8. Explain why, hydrogen and oxygen are considered elements whereas water is not

considered an element.

9. Compare the properties of metals and non- metals with respect to

(i) malleability (ii) ductility, and (iii) electrical conductivity

10. Choose the solutions from among the following mixtures:

Soil, Sea-water, Air, Coal, Soda-water

11. Give two reasons for supposing that water is a compound and not a mixture.

12. List five characteristics by which compounds can be distinguished from mixtures.

13. (a) Differentiate between homogeneous and heterogeneous mixtures.

(b) Classify the following materials as homogeneous mixtures and heterogeneous

mixtures.

Soda-water, Wood, Air, Soil, Vinegar, Alcohol and water mixture, Petrol and

water mixture, Chalk and water mixture, Sugar and water mixture, Copper

sulphate solution.






this is an question paper can any one solve I will mark you as brainliest​

Answer 1

Answer:

1. Mixtures

2. Air

3. H2O - compound

He- element

Cl2- compound

CO- compound

Co- element

4. (A) malleability

( B) ductability

5. Iron, iron, calcium oxide, mercury are pure substances.

6. Other name for impure substances is *mixtures*.

Example- Air, Soil, Chalk in water etc.

7.

air is mixture because.....

1) it is mixture of various gases like nitrogen, carbon dioxide , oxygen and many inert gas.

2) there is variable composition.

3) moreover dust particles and water vapour is present.

and water is a compound because.......

1) it compounds are bound together chemically.

2) it components cannot be separated by physical means.

3) Its constituent elements does not show their properties.

8. Hydrogen and oxygen are made up of same kinds of elements whereas water consists of both hydrogen and oxygen atoms chemically bonded in the ratio 2:1. Water has different kinds of elements.

9. (i)metals are malleable while non metals are not malleable.

(ii) metals are ductile but non metals are not ductile.

(iii) metals are good conductors of electricity while non metals are generally poor conductors of electricity.

10. Sea water , air and soda

11. Water is formed by the chemical bond between 2 hydrogen and one oxygen atom.

A bond between atoms of water can be broken by chemical reaction. Whereas, in a mixture, components are separated by physical means. Example:- Sand and water.

Atoms of water cannot be separated by the physical process.

Hence, water is a compound because it can only be separated into hydrogen and oxygen atom by chemical reaction.

12. Compounds:

It is a pure substance

It cannot be separated by physical method

Elements lose  their properties in compounds

Its composition is fixed

It has a fixed melting point

MIXTURES:

It is an impure substance

Cant be separated by physical method

Substances forming mixture retain their properties

It has no fixed composition

It has no sharp melting point

13. (A) (I) Homogeneous mixtures have uniform composition throughout the mixture.

(II) The whole mixture is in same phase.

(III) Components are not visible to the naked eye.

(IV) Components cannot be separated easily.

Eg.: Sugar + Water → Sugar solution (I) Heterogeneous mixture have composition which may vary from point to point.

(II) Substances can be of two phases and layers may separate.

(III) Component of mixture can be seen easily.

(IV) Components can be separated easily.

Eg.: Salt + Sand

(B) homogeneous mixture:-

alcohol and water mixture,sugar and water mixture, vinegar.

heterogeneous mixture:-

wood, copper sulphate solution,air, soil, petrol.and water mixture, water and chalk mixture.

Answer 2

Answer:

1. Mixtures are the materials which contain at least two pure substances and show the properties of the constituents.

2. Air is a mixture.

3. $H_2O$ is a compound.

   $He$ is an element.

   $Cl_2$ is an element.

   $CO$ is a compound.

   $Co$ is an element.

4. a) Malleability

   b) Ductility

5. Ice, Iron, Mercury  are pure substances.

6. The other name for impure substance is mixture. Example: Air is a mixture and salt water mixture.

7. The three why we think air is a mixture because:-

• Compounds are bound together chemically but not mixture.
• It's components can be separated by physical processes.
• It's composition is not fixed.

The three reasons why we think water is a compound and not a mixture:-

• It's components cannot be separated by physical means and only through chemical means.
• It has a fixed composition
• Its properties are entirely different from their components properties.

8. Hydrogen and oxygen are considered as elements which cannot split into different substances by applying any kind of energy like heat or electricity whereas water is a composed of constituents like hydrogen and oxygen in a fixed proportion and it can be split up by applying energy.

9.  Metals are malleable, ductile and good conductors of heat and electricity whereas non metals are not malleable, ductile and are poor conductors of heat and electricity.

10.  Sea water, air, soda water.

11. Similar to 7.

12.  Difference b/w compounds and mixture:

• They are chemically bound whereas mixture is not.
• They are separated by chemical means whereas mixture is separated through physical means.
• It's properties are different from their original components whereas the properties are different for different components(the same)
• Compounds have definite proportions whereas mixture does not.
• Compounds have fixed boiling and melting point whereas mixture does not.

13.  a) Homogeneous and heterogeneous mixture:-

• A homogeneous mixture is a solid, liquid or gaseous mixture that has the same proportions of its components throughout any given sample whereas it is not same with heterogeneous mixture.
• Uniform composition in homogeneous whereas Non-uniform composition for heterogeneous.

b) Homogeneous - Soda water, air, vinegar, sugar water mixture, alcohol and water mixture and copper sulphate solution.

Heterogeneous - Wood,  chalk water mixture, petrol water mixture, soil.

{That's a long answer but hope it helps you!}