Chemical reactions and equations

Chemical formula of quick lime is :

• CaO

• Ca(OH)2

• CaCO3

• CO2

Silver article turns black when kept in open for a few days due to formation of

• H2S

• AgS

• AgSO4

• Ag2S

Tags

NGSS.HS-PS1-1

NGSS.HS-PS1-2

A chemical equation should be balanced to :

• show conservation of energy

• show conservation of mass

• to make equation attractive

• All of the above

Tags

NGSS.HS-PS1-7

In which of the following process a chemical reaction has taken place?

• Ice melts into water

• A wet shirt got dried in sunlight

• A brown layer is formed over iron rod kept in air

• sugar getting dissolved in water

Tags

NGSS.MS-PS1-2

Which of the following is not a chemical reaction ?

• Formation of salt solution

• Milk turns sour in hot weather

• Burning of match stick

• Contamination of food

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

An unbalanced chemical equation is written in :

• Simple form

• Proper form

• Unorganized form

• Skeletal form

The reaction in which two compound exchange their ions to form two new compounds is called

• displacement reaction

• combination reaction

• redox reaction

• double displacement reaction

Which of the following gases can be used for storage of fresh sampel of an oil for a long time?

• Carbon dioxide or oxygen

• Nitrogen or helium

• Helium or oxygen

• Nitrogen or oxygen

The chemical formula of lead sulphate is :

• Pb2SO4

• Pb(SO4)2

• PbSO4

• Pb2(SO4)3

Which of the following reactions involves the combination of two elements :-

• CaO + CO₂ -> CaCO₃

• 4Na + O₂ -> 2Na₂O

• SO₂ +(1/2)O₂ -> SO₃

• NH₃ + HCI -> NH₄CI