Answer
(a) Yes, there will be precipitation.
$NaBr(aq) + AgNO_3(aq) -- \gt AgBr(s) + NaNO_3(aq)$
(b) Yes, there will be precipitation.
$2KCl(aq) + Pb(NO_3)_2(aq) -- \gt 2KNO_3(aq) + PbCl_2(s)$
Work Step by Step
1. Write the double replacement reaction.
(a) $NaBr(aq) + AgNO_3(aq) -- \gt AgBr + NaNO_3$
(b) $KCl(aq) + Pb(NO_3)_2(aq) -- \gt KNO_3 + PbCl_2$
2. Analyze the solubility of each product.
$AgBr$ and $PbCl_2$: Almost all $Br^-$ and $Cl^-$ salts are soluble, with the exception of the ones with $Ag^+$, $Pb^{2+}$ or $Hg_2^{2+}$, therefore, these salts are insoluble.
$NaNO_3$ and $KNO_3$, all $Na^+$ and $K^+$ salts are soluble.
3. Now, write the equations, with the correct balance of coefficients and physical states:
(a) $NaBr(aq) + AgNO_3(aq) -- \gt AgBr(s) + NaNO_3(aq)$
(b) $2KCl(aq) + Pb(NO_3)_2(aq) -- \gt 2KNO_3(aq) + PbCl_2(s)$
