Physical and Chemical Changes (Class 7th cbse)

Evolution of gas is confirmed by appearance of ___________________ in a chemical reaction if one of the reactants is a liquid or in solution form.

• Galvanization

• Reactants

• Effervescence

• Products

This is which type of chemical reaction?
(It can have more than one correct answer)

Zn + H2SO4 = ZnSO4 + H2 

• Single displacement reaction

• Oxidation Reaction

• Double displacement reaction

• Reduction reaction

The insolube substance formed during a chemical reaction is called _____________.

• Heat

• Precipitate

• liquid

• gas

What is the chemical composition of BAKING SODA?

• CH3COOH

• Fe(OH)3

• Al2(SO4)3

• NaHCO3

What are the two ways in which decomposition reaction normally takes place?

• Passing Electricity

• Cooling

• Galvanization

• Heating

The process of depositing a layer of _______ on iron is called galvanization.

• Chromium

• Aluminium

• Zinc

• Silver

What is the chemical composition of VINEGAR?

• CuSO4

• CH3COOH

• NaHCO3

• AgNO3

What are the two types of double displacement reactions?

• Exothermic reaction

• Precipitation reaction

• Decomposition reaction

• Neutralization reaction

The reaction in which heat is absorbed is called ________________ reaction and the reaction in which heat is released is called ________________ reaction.

• Neutralization, Precipitation

• Precipitation, Neutralization

• Exothermic, Endothermic

• Endothermic, Exothermic

In a single displacement reaction a ____ ________ element replaces a ____ ________ element.

• less reactive, more reactive

• more reactive, less reactive

• gas state, liquid state

• liquid state, gas state