[Tex/LaTex] Using greek letters in a table when using Palatino font

Question

I am trying to write an article with Palatino font. I loaded the following packages, among others:

\usepackage{mathpazo}
\usepackage{avant}

In my first attempt of writing the letter $\Omega$ it worked. But when I attempted to write this letter inside of a table cell, I obtained the following output:

Where instead of the black squares in the middle column, it should appear the letter $\Omega$. The piece code I wrote for this table is the following:

\begin{table}[ht!]
\centering
\begin{tabular}{|c|c|c|}
   \hline
   Filtre & Resistència & Condensador\\
   \hline
   1 &  $R_1=10\hspace{1mm} \mathrm{k\Omega}$ & $C_1=1\hspace{1mm}\mathrm{nF}$\\
   2 & $R_2=100\hspace{1mm} \mathrm{\Omega}$ & $C_2=100\hspace{1mm} \mathrm{nF}$\\
   3 & $R_3=1\hspace{1mm} \mathrm{M\Omega}$ & $C_3=10\hspace{1mm} \mathrm{pF}$\\
   \hline
\end{tabular}
\end{table}

So there's my question. I don't know how to fix this, maybe I should load a package that allows me to use greek letters in a table when using this font, or something different. If I write greek letters out of a table, it works perfectly.

Answer 1

\mathrm{\Omega} is wrong as it points to a non existent character. You should use siunitx, instead of doing manual markup.

\documentclass{article}
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}
\usepackage[catalan]{babel}
\usepackage[sc]{mathpazo}
\usepackage{siunitx}

\begin{document}

\begin{tabular}{|c|c|c|}
\hline
Filtre & Resistència & Condensador\\
\hline
1 & $R_1=  \SI{10}{\kilo\ohm}$ & $C_1=\SI{1}{\nano\farad}$ \\
2 & $R_2= \SI{100}{\ohm}$      & $C_2=\SI{100}{\nano\farad}$ \\
3 & $R_3=   \SI{1}{\mega\ohm}$ & $C_3=\SI{10}{\pico\farad}$ \\
\hline
\end{tabular}

\end{document}