CBSE Class VIII Science Solutions

Displaying 5 out of 32 questions & answers.
Q1.

Multiple-Choice Questions

Tick (√) the correct option:

  1. The total number of elements known to us are:
    1. 110
    2. 116
    3. 120
    4. 118
  2. Which of the following is a metal?
    1. Arsenic
    2. Aluminium
    3. Germanium
    4. Silicon
  3. Non-metals exist as
    1. Solid
    2. Liquid
    3. Gas
    4. All of these
  4. Silver, gold and platinum are
    1. Noble metals
    2. Metals
    3. Non-metals
    4. Inert gases
  5. Which of the following metals is used for food packaging?
    1. Iron
    2. Sodium
    3. Silver
    4. Magnesium
  6. The property by which metals can be drawn into wires is called
    1. Malleability
    2. Ductility
    3. Conductivity
    4. Sonority
  7. Metals react with dilute acids to form salt and
    1. Oxygen
    2. Nitrogen
    3. Hydrogen
    4. Water
  8. Which of the following is a non-metal that exists in liquid state?
    1. Oxygen
    2. Sulphur
    3. Bromine
    4. Chlorine
  9. Which of the following is used for making pencil lead?
    1. Diamond
    2. Phosphorus
    3. Silicon
    4. Graphite
  10. Which of the following is a metal that can be cut with a knife?
    1. Sodium
    2. Lithium
    3. Magnesium
    4. None of these
  11. Which of the following non-metals is lustrous?
    1. Graphite
    2. Iodine
    3. Sulphur
    4. Both a and b
  12. Which of the following metals is used for making filament of an incandescent bulb?
    1. Sodium
    2. Tungsten
    3. Gold
    4. All of these
  13. A more reactive metal displaces less reactive metal from its salt solution. This is called
    1. Combination reaction
    2. Decomposition reaction
    3. Displacement reaction
    4. None of these
  14. Liquid hydrogen is used
    1. As a rocket fuel
    2. In welding metals
    3. In manufacture of fertilisers
    4. To make antiseptic creams
  15. The smallest unit of an element is
    1. Molecule
    2. Atom
    3. Particles
    4. Electrons
S A M P L E
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Answer:
S A M P L E
  1. (d) 118
  2. (b) Aluminium
  3. (c) All of these
  4. (a) Noble metals
  5. (c) Silver
  6. (b) Ductility
  7. (c) Hydrogen
  8. (c) Bromine
  9. (d) Graphite
  10. (a) Sodium
  11. (d) Both a and b
  12. (b) Tungsten
  13. (c) Displacement reaction
  14. (a) As a rocket fuel
  15. (b) Atom
Q2.

Fill in the blanks:

  1. The most reactive metal is placed on the _________ and the least reactive metal at the _________ of the reactivity series.
  2. Mg + _________ → Mg (OH)2 + H2
  3. Graphite and iodine have _________ and _________.
  4. 4Fe + H2O + O2 → _________.
  5. Metals react with dilute acids and liberate _________.
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Answer:
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  1. top, bottom
  2. 2H2O
  3. shiny, lustrous
  4. 2Fe2O3
  5. hydrogen
Q3.

Tick (√) the correct and cross (X) the wrong statement:

  1. Aluminium is more reactive than zinc.
  2. Copper does not-get corroded.
  3. All ores are minerals, but all minerals are not ores.
  4. Metal surfaces should be repainted time to time.
  5. Non-metals combine with oxygen to form basic oxides.
  6. Magnesium forms black colour powder of magnesium oxide.
  7. The reactivity of all metals is not the same.
  8. Electric wires are made of iron.
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Answer:
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Q4.

Match the following:

Column AColumn B
1. Acidic oxides(a) 'Pop' sound
2. Basic oxides(b) Magnesium oxide
3. Iron(c) Yellow in colour
4. Hydrogen(d) Non-metals
5. White powder(e) Gold
6. Sulphur(f) Violet
7. Rust(g) Liquid state
8. Malleable(h) Metals
9. Iodine(i) Hydrated iron oxide
10. Bromine(j) Corrosion

 

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Answer:
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  1. (d) Non-metals
  2. (h) Metals
  3. (i) Hydrated iron oxide
  4. (a) 'Pop' sound
  5. (b) Magnesium oxide
  6. (c) Yellow in color
  7. (j) Corrosion
  8. (h) Metals
  9. (f) Violet
  10. (g) Liquid state
Q5.

Find the odd one out:

  1. Gold, silver, graphite and platinum.
  2. Sulphur, diamond, graphite and iodine.
  3. Iron, mercury, brass, gold and diamond.
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Answer:
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answer not shown
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