किस प्रकार की अभिक्रिया में दो अलग-अलग परमाणुओं या परमाणुओं के समूहों (आयनों) का आदान-प्रदान होता है?

Which of the following is an example of a double displacement reaction?

In the thermal decomposition reaction of lead nitrate given below, which compound fills the blank box? 2Pb(NO3)2 (s) → [ ? ] + 4NO2 (g) + O2 (g)

Choose the balanced equation for the following chemical reaction: Hydrogen + Chlorine → Hydrogen Chloride