The dioxides and monoxides of elements $X$ and $Y$ are amphoteric in nature. $X$ and $Y$ are respectively.

Silver nitrate is prepared by

Which set of elements form electron precise hydrides?

Match the following:
| List-$I$ | List-$II$ |
| :--- | :--- |
| $A$. Carbon black | $I$. Electrodes in batteries |
| $B$. Graphite | $II$. Extraction of metals |
| $C$. Diamond | $III$. Abrasive |
| $D$. Activated charcoal | $IV$. Filler in automobile tyres |
| | $V$. Air conditioning system |

What is meant by $Tin \ Plague$?

Polyphosphates are used as water softening agents because they .......