Physical and Chemical Changes
Science · Class 7 · CBSE
ScienceClass 7CBSEEasy
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The process of depositing layer of zinc on iron is known as
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All questions in this chapter
28 multiple choice questions on Physical and Chemical Changes — Science, Class 7. Open any question for its answer and explanation.
Q1.Stainless steel is resistant to rusting, though it is made from iron. Why?
- A.Because it is steel
- B.Because it is resistant to stains
- C.Because it is made from iron, chromium, nickel and manganese
- D.Because it is galvanised
Q2.Why are the water pipes in our homes galvanised?
- A.To prevent rusting of iron
- B.To coat them with a layer of zinc
- C.To prevent their leakage and breakage
- D.All of them
Q3.For rusting, which of the following is essential?
- A.Presence of water is essential
- B.Presence of oxygen is essential
- C.Presence of both water and oxygen is essential
- D.Presence of air is essential
Q4.Fraction of ship's iron has to be replaced every year because
- A.It prevents rusting of iron
- B.Its color fades away
- C.Ship can move properly in water only after replacement
- D.All the above
Q5.Select the following chemical changes: (i) Copper metal drawn into wires (ii) Burning of paper (iii) Digestion of food (iv) Breaking of glass
- A.(i), (ii) & (iii)
- B.(ii) & (iii)
- C.(i) & (iv)
- D.(i), (iii) & (iv)
Q6.While preparing copper sulphate crystals from copper sulphate solution, dilute sulphuric acid is used instead of concentrated sulphuric acid, because
- A.Concentrated sulphuric acid is corrosive in nature
- B.Dilute sulphuric acid makes large crystals
- C.Concentrated acid is ineffective
- D.Both (a) & (b)
Q7.The process of obtaining pure crystals of copper sulphate from copper sulphate solution is known as
- A.Galvanization
- B.Evaporation
- C.Crystallization
- D.Rusting
Q8.Complete the reaction: Carbon dioxide + Lime water → ___ + ___
- A.Calcium carbonate, water
- B.Calcium hydroxide, oxygen
- C.Calcium oxide, water
- D.Calcium carbonate
Q9.When magnesium ribbon burns in air, it leaves an ash which is
- A.Mg(OH)2
- B.MgO
- C.MgS
- D.MgSO4
Q10.When magnesium oxide (MgO) reacts with water to form magnesium hydroxide [Mg(OH)2], a base, it turns ___ litmus to ___
- A.Blue, red
- B.Blue, colourless
- C.Red, blue
- D.Colourless, blue
Q11.Baking soda is common name for
- A.Sodium carbonate
- B.Sodium hydrogen carbonate
- C.Calcium carbonate
- D.Sodium hydroxide
Q12.Ozone layer is present in
- A.Atmosphere
- B.Clouds
- C.Soil
- D.Water
Q13.Explosion of a firework produces
- A.Heat & light
- B.Heat only
- C.Gases only
- D.Heat, light, sound & unpleasant gases
Q14.Burning is a chemical change and is always accompanied by production of
- A.Sound
- B.Heat
- C.Gas only
- D.Sound & heat
Q15.The process of depositing layer of zinc on iron is known as
- A.Galvanization
- B.Crystallization
- C.Rusting
- D.Layering
Q16.When copper sulphate reacts with iron, green coloured ___ solution and brown coloured ___ deposition is formed
- A.Iron oxide, copper sulphide
- B.Iron sulphate, copper
- C.Iron sulphate, copper oxide
- D.Iron sulphide, copper oxide
Q17.Lime water turns milky when ___ gas is passed through it
- A.Carbon dioxide
- B.Hydrogen
- C.Oxygen
- D.Nitrogen dioxide
Q18.Chemical change is always accompanied by: (i) Production of sound (ii) Heat and light (iii) Change in mass (iv) Change in color
- A.(i), (ii) & (iii)
- B.(ii) & (iv)
- C.(i) only
- D.(i), (ii) & (iv)
Q19.Stainless steel is made by mixing iron with carbon and metals like ___ to iron
- A.Magnesium, sodium, calcium
- B.Chromium, Nickel, Manganese
- C.Cobalt, Potassium, Iron
- D.Potassium, Sodium, Chromium
Q20.During rusting the layer which is deposited on the surface of iron is
- A.Fe2O
- B.Fe2O2
- C.Fe2O3.xH2O
- D.Fe(OH)3
Q21.To prevent iron from rusting a coating of this metal is deposited
- A.Calcium
- B.Chromium
- C.Sodium
- D.Potassium
Q22.The elements required for rusting of iron
- A.Oxygen and moisture
- B.Only oxygen
- C.Hydrogen and oxygen
- D.Only water vapours
Q23.The gas in the atmosphere which acts as a natural shield against ultra violet radiations
- A.Oxygen
- B.Sulphur dioxide
- C.Hydrogen
- D.Ozone
Q24.When vinegar reacts with baking soda the gas evolved is
- A.Hydrogen
- B.Oxygen
- C.Carbon dioxide
- D.Nitrogen dioxide
Q25.Blue vitriol is the common name of
- A.Copper sulphate
- B.Copper oxide
- C.Copper hydroxide
- D.Magnesium sulphate
Q26.Pick out physical changes from the following: (i) Rusting of iron (ii) Dissolving salt in water (iii) Change of water to ice (iv) Cooking of food
- A.(i) & (ii)
- B.(ii) & (iii)
- C.(i), (ii) & (iii)
- D.(iii) & (iv)
Q27.When magnesium ribbon is burnt, a brilliant ___ flame is observed
- A.Yellow
- B.Blue
- C.White
- D.Green
Q28.Select the correct alternative(s): (i) Melting of ice is a physical change (ii) A physical change is due to change in physical properties of a substance (iii) A physical change is always irreversible in nature (iv) Burning of candle is an example of physical change
- A.(i) & (ii)
- B.(i) & (iv)
- C.(i), (ii) & (iv)
- D.(ii) & (iii)