For something simple like you specified I would go for two simple definitions, \Que
and \Ans
. For more complicated formatting and features check the answers package.
\documentclass{article}
\usepackage{lipsum}
\newcounter{question}
\setcounter{question}{0}
\begin{document}
\newcommand\Que[1]{%
\leavevmode\par
\stepcounter{question}
\noindent
\thequestion. Q --- #1\par}
\newcommand\Ans[2][]{%
\leavevmode\par\noindent
{\leftskip37pt
A --- \textbf{#1}#2\par}}
\Que{Here first question would come}
\Ans{\lipsum[1]\lipsum[1]}
\Que{Here second question would come}
\Ans{\lipsum[1]\lipsum[1]}
\end{document}