In physical changes the solutes and solvents can easily be separated by

  • evaporation
  • distillation
  • heating
  • both a and b

The process of breaking down of any substance into smaller substances by heating, is called

  • decomposition
  • evaporation
  • thermal decomposition
  • melting

Dilute acids and alkalis react together to form

  • salt
  • water
  • gases
  • both a and b

Irreversible changes include

  • burning of paper
  • rusting of iron
  • corrosion of material
  • all of them

Changes occur in matter at

  • specific times
  • all the times
  • thermal reaction
  • continuously

Zinc salt reacts with dilute shulphuric acid to form zinc salt and

  • hydrogen
  • oxygen
  • carbon dioxide
  • carbon monoxide

Natural gas is made up of compound

  • carbon
  • methane
  • ethene
  • ethane

Power machines in factories and vehicles are examples of

  • combustion
  • thermal decomposition
  • evaporation
  • combination

Natural gas is more efficient and produces less

  • pollution
  • heat
  • reaction
  • less evaporation

Fuel obtained from fossils is known as

  • decayed animal's oil
  • decayed plant's extract
  • fossils fuel
  • crude oil

The process in which reactants react together to form a product, is called

  • chemical reaction
  • chemical change
  • chemical process
  • chemical procedure

At room temperature iron and sulphur

  • do no react
  • react
  • vigorously react
  • somehow react

If two or more substances are combined to form a new substance, the chemical reaction is termed as

  • thermal decomposition
  • combination
  • addition
  • combustion

When substance combines with oxygen while burning, the reaction is termed as

  • combustion
  • burning
  • evaporation
  • both a and b

If both water and carbon dioxide is given to plant it will not be able to prepare its own food in absence of

  • sugar
  • soil
  • sunlight
  • fertilizers

Melting, freezing, boiling, evaporation and condensation are all

  • physical change
  • chemical change
  • complex change
  • electrical change

Chemical change involves the formation of

  • products
  • new substances
  • salts
  • water

The change which is not accompanied by formation of new substance is called a

  • physical change
  • chemical change
  • complex change
  • electrical change

Chalk, limestone, marble, eggshells and seashells are made of

  • calcium hydroxide
  • calcium oxide
  • calcium carbonate
  • calcium chloride

The conservation of mass is obtained when the total mass of reactants is equal to total mass of

  • products
  • molecules
  • protons
  • atoms
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