List of top Science Questions on Chemical Reactions asked in CBSE Class X

Consider the unbalanced chemical equations of the chemical reactions listed below:

1. \(\text{CaO} + \text{H}_2\text{O} \rightarrow \text{Ca(OH)}_2\)
2. \(\text{Pb(NO}_3\text{)}_2 \rightarrow \text{PbO} + \text{NO}_2 + \text{O}_2\)
3. \(\text{CuSO}_4 + \text{Fe} \rightarrow \text{FeSO}_4 + \text{Cu}\)
4. \(\text{Na}_2\text{SO}_4 + \text{BaCl}_2 \rightarrow \text{BaSO}_4 + \text{NaCl}\)

Consider the following substances : (i) Acidified K$_2$Cr$_2$O$_7$
(ii) Alkaline KMnO$_4$
(iii) Oxygen
(iv) Hydrogen
Out of these, the commonly used oxidising agents are :

Assertion (A) : In the reaction, Na$_2$SO$_4$ + BaCl$_2$ $\longrightarrow$ BaSO$_4$ + 2NaCl, sodium chloride is precipitated.
Reason (R) : When an aqueous solution is added to another aqueous solution, an insoluble substance is formed, which is called precipitate.