Four test-tubes are arranged as illustrated, containing $\text{AgNO}_3(\text{aq})$, $\text{Cu(NO}_3)_2(\text{aq})$, $\text{Pb(NO}_3)_2(\text{aq})$ and $\text{NaNO}_3(\text{aq})$. What happens when dilute hydrochloric acid is added to each test-tube? Key: $\times$ = clear solution, $\checkmark$ = precipitate formed.
- AW $\times$, X $\checkmark$, Y $\times$, Z $\checkmark$
- BW $\checkmark$, X $\times$, Y $\checkmark$, Z $\times$
- CW $\checkmark$, X $\times$, Y $\checkmark$, Z $\checkmark$
- DW $\checkmark$, X $\times$, Y $\times$, Z $\times$