CHEMISTRY

 CHEMISTRY

INTRODUCTION OF CHEMISTRY

ELEMENT,COMPOUNDS AND MIXTURES

MATTER

Elements, Compounds, and Mixtures - MCQ Quiz
Class VI

Section A: Pure Substances and Elements

1. Which of the following is a pure substance?
   a) Air
   b) Milk
   c) Water
   d) Sand
   Answer: c) Water

2. An element is made up of:
   a) Only one type of atom
   b) Two or more types of atoms
   c) Two or more elements
   d) Molecules of different elements
   Answer: a) Only one type of atom

3. Which of the following is NOT an element?
   a) Oxygen
   b) Silver
   c) Brass
   d) Carbon
   Answer: c) Brass

Section B: Metals, Non-Metals, and Metalloids

4. Which of the following is a property of metals?
   a) Brittle
   b) Poor conductor of heat
   c) Malleable
   d) Dull appearance
   Answer: c) Malleable

5. Which of the following is a non-metal?
   a) Iron
   b) Copper
   c) Sulfur
   d) Aluminum
   Answer: c) Sulfur

6. Metalloids have properties of:
   a) Only metals
   b) Only non-metals
   c) Both metals and non-metals
   d) None of these
   Answer: c) Both metals and non-metals

Section C: Symbols of Elements

7. What is the chemical symbol of gold?
   a) Gd
   b) Ag
   c) Au
   d) Go
   Answer: c) Au

8. Which of the following symbols represents Oxygen?
   a) O₂
   b) O
   c) Ox
   d) Om
   Answer: b) O

Section D: Atomicity and Compounds

9. What is the atomicity of Oxygen (O₂)?
   a) 1
   b) 2
   c) 3
   d) 4
   Answer: b) 2

10. Which of the following is a monoatomic element?
    a) Hydrogen
    b) Nitrogen
    c) Helium
    d) Oxygen
    Answer: c) Helium

11. A compound is formed by the combination of:
    a) Atoms of the same element
    b) Atoms of different elements
    c) Only metals
    d) Only non-metals
    Answer: b) Atoms of different elements

12. Which of the following is a compound?
    a) Air
    b) Iron
    c) Water
    d) Oxygen
    Answer: c) Water

Section E: Chemical Formulas and Balancing Equations

13. The chemical formula of water is:
    a) H₂O₂
    b) H₂O
    c) HO₂
    d) H₂O₃
    Answer: b) H₂O

14. Which of the following is a correctly balanced equation?
    a) H₂ + O₂ → H₂O
    b) 2H₂ + O₂ → 2H₂O
    c) H₂ + O₂ → 2H₂O
    d) 2H₂ + 2O₂ → H₂O
    Answer: b) 2H₂ + O₂ → 2H₂O

Section F: Mixtures and Their Types

15. A mixture is formed by:
    a) Two or more pure substances
    b) Only one element
    c) Only one compound
    d) A single type of molecule
    Answer: a) Two or more pure substances

16. Which of the following is a homogeneous mixture?
    a) Sand and water
    b) Sugar solution
    c) Oil and water
    d) Soil
    Answer: b) Sugar solution

17. Which of the following is a heterogeneous mixture?
    a) Salt solution
    b) Air
    c) Milk
    d) Oil and water
    Answer: d) Oil and water

Section G: Separation of Mixtures

18. Which method is used to separate a soluble solid from a liquid?
    a) Filtration
    b) Evaporation
    c) Sieving
    d) Magnetism
    Answer: b) Evaporation

19. Iron and sulfur can be separated by:
    a) Evaporation
    b) Filtration
    c) Using a magnet
    d) Sedimentation
    Answer: c) Using a magnet

20. The best method to separate salt from seawater is:
    a) Distillation
    b) Filtration
    c) Handpicking
    d) Sieving
    Answer: a) Distillation

Short Question-Answer Set

1. What is an element?

   • An element is a pure substance made up of only one type of atom.

2. Give two examples of elements.

   • Oxygen (O), Iron (Fe).

3. What is a compound?

   • A compound is a substance formed when two or more elements combine chemically in a fixed ratio.

4. Give two examples of compounds.

   • Water (H₂O), Carbon dioxide (CO₂).

5. What is a mixture?

   • A mixture is a combination of two or more substances that are not chemically combined.

6. Give two examples of mixtures.

   • Air, Saltwater.

7. What is the main difference between a compound and a mixture?

   • A compound has a fixed composition and chemical bonding, while a mixture has no fixed composition and no chemical bonding.

8. What are the two types of mixtures?

   • Homogeneous mixture and Heterogeneous mixture.

9. Give one example of a homogeneous mixture.

   • Sugar dissolved in water.

10. Give one example of a heterogeneous mixture.

• Sand and water.

11. What is the chemical symbol of sodium?

• Na.

12. What is the chemical formula of carbon dioxide?

• CO₂.

13. What is atomicity?

• Atomicity is the number of atoms present in a molecule of an element.

14. Give one example of a monoatomic element.

• Helium (He).

15. What are metalloids?

• Metalloids are elements that have properties of both metals and non-metals.

16. Give two examples of metalloids.

• Silicon (Si), Boron (B).

17. What is the property of metals that allows them to be drawn into thin wires?

• Ductility.

18. Which separation method is used to obtain pure water from seawater?

• Distillation.

19. Which metal is a good conductor of electricity?

• Copper (Cu).

20. Which non-metal is essential for breathing?

• Oxygen (O₂).

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Here are 20 more short question-answer pairs on Elements, Compounds, and Mixtures for Class VI:

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Additional Short Question-Answer Set

21. What is a pure substance?

• A substance that has a fixed composition and definite properties.

22. Give two examples of pure substances.

• Gold (Au), Water (H₂O).

23. What is the smallest unit of an element?

• An atom.

24. What is the smallest unit of a compound?

• A molecule.

25. What is the atomicity of ozone (O₃)?

• Three (O₃ is triatomic).

26. Which element is the most abundant in the Earth's crust?

• Oxygen (O).

27. Which element is used in making electrical wires?

• Copper (Cu).

28. What is the chemical symbol of Iron?

• Fe.

29. What is malleability?

• The property of metals that allows them to be hammered into thin sheets.

30. Give two examples of non-metals.

• Carbon (C), Sulfur (S).

31. Which non-metal exists in liquid form at room temperature?

• Bromine (Br).

32. Which metal is liquid at room temperature?

• Mercury (Hg).

33. What is an alloy?

• A mixture of two or more metals or a metal with a non-metal.

34. Give two examples of alloys.

• Bronze (Copper + Tin), Brass (Copper + Zinc).

35. What is the process of separating insoluble solids from a liquid called?

• Filtration.

36. Which method is used to separate iron fillings from sand?

• Magnetic separation.

37. What is the process of obtaining salt from seawater called?

• Evaporation.

38. Name a gas that does not support combustion.

• Carbon dioxide (CO₂).

39. Which gas is used in balloons and is lighter than air?

• Helium (He).

40. Which element is necessary for plants to make their food?

• Carbon (C) in the form of Carbon Dioxide (CO₂).

True or False Questions

1. All elements are made up of only one type of atom. (True)

2. Brass is an element. (False)

3. Oxygen (O₂) is a compound. (False)

4. Metals are good conductors of electricity. (True)

5. Non-metals are usually ductile. (False)

6. Water (H₂O) is a mixture of hydrogen and oxygen. (False)

7. Carbon dioxide (CO₂) is a compound. (True)

8. Mixtures have a fixed composition like compounds. (False)

9. Air is a homogeneous mixture. (True)

10. A solution of sugar in water is a heterogeneous mixture. (False)

11. Iron can be separated from a mixture using a magnet. (True)

12. Distillation is used to separate soluble solids from liquids. (True)

13. All metals are solids at room temperature. (False) (Mercury is a liquid metal.)

14. Helium (He) is a non-metal. (True)

15. The atomicity of nitrogen (N₂) is two. (True)

16. Metalloids show properties of both metals and non-metals. (True)

17. Filtration can be used to separate sand from water. (True)

18. Saltwater is a heterogeneous mixture. (False) (It is homogeneous.)

19. The formula of ammonia is NH₃. (True)

20. Sulfur is a metal. (False)

1. Define an element. Give examples and explain its properties.

Answer: An element is a pure substance that is made up of only one type of atom and cannot be broken down into simpler substances by chemical means. Elements are classified into metals, non-metals, and metalloids based on their properties.

• Examples: Oxygen (O), Iron (Fe), Hydrogen (H)

• Properties of elements:

  • Have a fixed melting and boiling point.

  • Can exist in solid, liquid, or gaseous states.

  • Each element has a unique chemical symbol.

2. What are compounds? How are they different from elements? Give examples.

Answer: A compound is a pure substance formed when two or more elements chemically combine in a fixed ratio. It has properties different from the elements that form it.

• Examples: Water (H₂O), Carbon Dioxide (CO₂)

• Differences between Elements and Compounds:

  Property	Element	Compound
  Composition	Made of only one type of atom	Made of two or more different atoms
  Separation	Cannot be broken down by chemical means	Can be broken down into simpler substances
  Properties	Retains the properties of its atoms	Has new properties different from its elements

3. Explain the different types of mixtures with examples.

Answer: Mixtures are substances formed by combining two or more substances without any chemical bonding. They are classified as:

• Homogeneous Mixture: A mixture in which the components are evenly distributed and cannot be seen separately.

  • Example: Saltwater, Air, Sugar solution

• Heterogeneous Mixture: A mixture in which the components remain separate and can be seen easily.

  • Example: Sand and water, Oil and water, Salad

4. How can mixtures be separated? Explain different separation techniques with examples.

Answer: Mixtures can be separated using physical methods based on the properties of their components:

• Filtration: Used to separate insoluble solids from liquids. (Example: Sand and water)

• Evaporation: Used to separate dissolved solids from a liquid. (Example: Salt from seawater)

• Magnetic Separation: Used to separate magnetic substances from non-magnetic ones. (Example: Iron filings from sand)

• Distillation: Used to separate liquids with different boiling points. (Example: Separating alcohol from water)

5. What are metals, non-metals, and metalloids? Give examples.

Answer: Elements are classified into three categories based on their properties:

• Metals: Elements that are shiny, good conductors of electricity and heat, malleable, and ductile.

  • Examples: Copper (Cu), Iron (Fe), Gold (Au)

• Non-metals: Elements that are brittle, poor conductors of heat and electricity, and not malleable.

  • Examples: Oxygen (O), Sulfur (S), Carbon (C)

• Metalloids: Elements that have properties of both metals and non-metals.

  • Examples: Silicon (Si), Boron (B), Arsenic (As)

6. What is atomicity? Explain with examples.

Answer: Atomicity refers to the number of atoms present in a molecule of an element.

• Types of Atomicity:

  • Monoatomic: Elements with single atoms (Example: Helium - He)

  • Diatomic: Elements with two atoms (Example: Oxygen - O₂)

  • Triatomic: Elements with three atoms (Example: Ozone - O₃)

  • Polyatomic: Elements with more than three atoms (Example: Phosphorus - P₄)

7. What are alloys? How are they useful? Give examples.

Answer: An alloy is a mixture of two or more metals, or a metal with a non-metal, to enhance properties like strength, durability, and resistance to corrosion.

• Examples:

  • Brass (Copper + Zinc) – Used in musical instruments and decorations.

  • Stainless Steel (Iron + Chromium + Nickel) – Used in utensils and buildings.

  • Bronze (Copper + Tin) – Used in statues and medals.

8. Explain the characteristics of compounds.

Answer: Compounds have unique properties that distinguish them from elements and mixtures:

• Formed by chemical combination of two or more elements.

• Have a definite composition by mass.

• Can be broken down into simpler substances by chemical methods.

• Have properties different from the elements that form them.

9. How is water different from a mixture of hydrogen and oxygen?

Answer: Water (H₂O) is a compound, while a mixture of hydrogen and oxygen is just a physical combination.

Property	Water (H₂O)	Mixture of Hydrogen & Oxygen
Composition	Chemically combined	Physically mixed
Properties	Has unique properties	Retains properties of hydrogen & oxygen
Separation	Can only be broken down chemically	Can be separated by physical means

10. Why is air considered a mixture and not a compound?

Answer: Air is a mixture because:

• The gases in air (oxygen, nitrogen, carbon dioxide) are not chemically bonded.

• The composition of air varies from place to place.

• The components of air can be separated by physical methods like liquefaction and fractional distillation.

• Each gas in air retains its original properties.