gistfile1.tex

\documentclass[a4paper,answers]{exam}
\usepackage{booktabs}
\usepackage{amsmath}
\usepackage{fullpage}
\renewcommand{\questionlabel}{\textbf{\thequestion}}
\renewcommand{\thesection}{\arabic{section}}
\begin{document}
  \section*{Chapter 1}
  \setcounter{section}{1}
  \begin{questions}
    \numberwithin{question}{section}
    \setcounter{question}{1}
    \question
      Question is here.
    \begin{solution}
      Here comes the answer
    \end{solution}
  \end{questions}
  \section*{Chapter 2}
  \setcounter{section}{2}
  \begin{questions}
    \numberwithin{question}{section}
    \setcounter{question}{1}
    \question
      Question is here.
    \begin{solution}
      Here comes the answer
    \end{solution}
  \end{questions}
\end{document}