which of the following reaction is incorrect
  • Carbon dioxide (CO2) + Lime water[Ca(OH)2]  -> Calcium Carbonate (CaCO3) + Water (H2O]
  • Vinegar (Acetic acid) + Baking soda(Sodium hydrogen carbonate) -> Carbon dioxide + other substances
  • Iron[Fe] + Oxygen [O2 ] + water (H2O) -> rust (iron oxide Fe3O4)
  • Magnesium oxide (MgO) + Water (H2O) ->Magnesium hydroxide [Mg(OH)2]
A man painted his main gate made up of iron, to (i) prevent it from rusting. (ii) protect it from sun. (iii). make it dust free (iv). make it look beautiful Which of the above statement(s) is/are correct?
  • (i) and (ii)
  • (i) and (iv)
  • only (ii)
  • i) and (iii)
What is the formula of rust?
  • Fe
  • None of these
  • FeO
  • (i) and (ii)
What is a physical change?
  • A physical change involves a change in the state of matter.
  • A physical change is a change in the chemical composition of matter.
  • A physical change is reversible.
  • A physical change is a type of change in which the form or appearance of matter changes, but its chemical composition remains the same.
Give an example of a physical change.
  • Burning wood into ash
  • Boiling water into steam
  • Freezing water into ice
  • Melting ice into water
Define a chemical change.
  • A chemical change is a process that involves physical changes only.
  • A chemical change is a process that does not involve any transformation.
  • A chemical change is a process in which one or more substances are converted into different substances with different properties.
  • A chemical change is a process where substances remain the same.
Provide an example of a chemical change.
  • Cutting a piece of paper
  • Boiling water
  • Mixing salt and sugar
  • Iron rusting
Explain what a reversible change is.
  • A reversible change is a change that is always permanent.
  • A reversible change is a change that cannot be undone.
  • A reversible change is a change that can be undone or reversed.
  • A reversible change is a change that only happens once.
Can you give an example of a reversible change?
  • Mixing salt in water
  • Burning paper into ashes
  • Boiling water into steam
  • Melting ice into water and freezing the water back into ice
Describe an irreversible change.
  • An irreversible change can be reversed easily
  • An irreversible change is a change that cannot be undone or reversed to its original state.
  • An irreversible change has no impact
  • An irreversible change is temporary
Share an example of an irreversible change.
  • Burning a piece of paper
  • Freezing water
  • Mixing salt in water
  • Melting ice cream
How can you identify a physical change?
  • Check if the change produces a new substance
  • Observe if the change alters the substance's physical state
  • Verify if the change affects the substance's color
  • Observe if the change can be reversed without altering the substance's chemical composition.
How can you distinguish a chemical change from a physical change?
  • Chemical changes are reversible, while physical changes are not.
  • Chemical changes involve the formation of new substances, while physical changes do not.
  • Physical changes always involve a change in color, while chemical changes do not.
  • Physical changes involve the formation of new substances, while chemical changes do not.
What happens to the particles during a chemical change?
  • Particles rearrange themselves to form new substances.
  • Particles disappear completely
  • Particles remain unchanged
  • Particles transform into energy
In what way do reversible changes differ from irreversible changes?
  • Reversible changes can be undone, while irreversible changes cannot.
  • Reversible changes cannot be observed, while irreversible changes can.
  • Reversible changes always lead to a decrease in entropy, while irreversible changes do not.
  • Reversible changes are faster than irreversible changes.
Why is it important to understand the different types of changes?
  • Understanding changes is not important
  • All changes are the same
  • It is important to understand the different types of changes to anticipate, plan for, and adapt to them effectively.
  • Ignoring changes leads to success
Discuss the impact of irreversible changes on the environment.
  • Irreversible changes on the environment have significant and lasting negative impacts on ecosystems, biodiversity, and human societies.
  • Reversible changes have a more significant impact on the environment
  • Irreversible changes do not affect ecosystems
  • The impact of irreversible changes on the environment is temporary
How can you reverse a reversible change?
  • Ignore the change and hope it reverses itself
  • Apply the same actions that caused the change
  • Perform the opposite actions that were done to make the change
  • Ask someone else to reverse the change
Which of the following is a physical change?
  • Rusting of iron
  • Melting of wax
  • Combustion of magnesium ribbon
  • Burning of candle
Which of the following is a chemical change?
  • Cooking of vegetables
  • Crumpling of paper
  • Cutting of fruits
  • Boiling of water
A chemical change may involve
  • Change in color only
  • Change in temperature only
  • Evolution of gas only
  • Any or all of the above
Which of the following processes is used to prevent articles from rusting?
  • Crystallization
  • Galvanization
  • Evaporation
  • Electolysis
Which of the following changes is accompanied by sound?
  • Photosynthesis
  • Spoilage of food
  • Explosion of fire works
  • Crumpling of paper
A change is a chemical change when it is accompanied by:
  • energy change
  • formation of new substances
  • change in chemical properties
  • all of the above
The shipping industry has to bear huge financial losses because of rusting of ships.The rusting of ships occurs because:
  • the body of ship is always in contact with water
  • the air around the ship is humid
  • presence of salts in sea water speed the process of rusting
  • all of the above
Expansion and contraction of metals is a:
  • physical change
  • chemical change
  • irreversible change
  • none of these
Hydrochloric acid is added to a beaker containing a piece of zinc. Zinc chloride is formed and hydrogen gas is released.This is an example of:
  • chemical reaction
  • physical change
  • crystallisation
  • none of these
Atmospheric pollution
  • Slow change
  • Due to chemical change
  • Physical change
  • The process of depositing one metal on another metal
Galvanisation
  • Slow change
  • Due to chemical change
  • Physical change
  • The process of depositing one metal on another metal
This metal is used as protective layer to prevent rusting in the process of galvanisation
  • Nickel
  • Copper
  • Chromium
  • Zinc
0 h : 0 m : 1 s

Answered Not Answered Not Visited Correct : 0 Incorrect : 0