\documentclass{book}
\usepackage{lipsum,adjmulticol}
\usepackage{color}
%%%%%%
\usepackage{newfile}
\usepackage{xifthen}
\usepackage{enumitem}
\usepackage{amsmath}
\usepackage{stackengine}
%%%%%%%%%%%%%%%
\usepackage{ptext}
%%%%%%%%%%%%%%%%%%%%% دستورات مربوط به زی پرشین
\usepackage{xepersian}
%\settextfont[Scale=1]{Yas}
%\settextfont{XB Niloofar}
\settextfont{XB Kayhan}
%%%%%%%%%%%%%%%%
\definecolor{myblueii}{RGB}{63,200,244}
\setlength{\parindent}{0pt}
\newoutputstream{solutions}
\openoutputfile{\jobname.solutions}{solutions}
\newcounter{exblock}[chapter]
\newcounter{exquestion}
\newcounter{exsubquestion}
\newlist{questionlist}{enumerate}{1}
\newlist{solutionlist}{enumerate}{1}
\newlist{subquestionlist}{enumerate*}{1}
\newlist{subsolutionlist}{enumerate*}{1}
\setlist[questionlist,solutionlist]{label=\arabic*.}
\setlist[subquestionlist,subsolutionlist]{label=(\alph*),itemjoin={},before=~}
\newcommand{\exheader}{%
    \ifthenelse{\value{exblock}>0}{\addtostream{solutions}{\noexpand\end{solutionlist}}}{}%%
        \refstepcounter{exblock}%1
        \label{ex.\arabic{exblock}}
           \setcounter{exquestion}{0}%
     \noindent\def\stackalignment{l}
    \stackunder[0pt]
    {\colorbox{myblueii}{\textcolor{white}{\textbf{\large مسائل\; \large \ref{ex.\arabic{chapter}}. \ref{ex.\arabic{exblock}}}}}}
      {\textcolor{myblueii}{\rule{\linewidth}{1pt}}}\medskip   
    \addtostream{solutions}{\noexpand\paragraph{مسائل \noexpand \ref{ex.\arabic{chapter}}.\ref{ex.\arabic{exblock}}, صفحه \noexpand\pageref{ex.\arabic{exblock}}}}%
    \addtostream{solutions}{\noexpand\begin{solutionlist}}
}
\newcommand{\printsolutions}{%
\begin{adjmulticols}{2}{-15.3em}{0pt}
    \ifthenelse{\value{exblock}>0}{\addtostream{solutions}{\noexpand\end{solutionlist}}}{}%
    \closeoutputstream{solutions}%
    \input{\jobname.solutions}%
   \end{adjmulticols}
}
\newenvironment{exercisescol}[2][]{%
    \begin{adjmulticols}{2}{0em}{0pt}%
       \begin{questionlist}[start=\value{exquestion}+1, #1]%
  }{%
    \end{questionlist}%
    \end{adjmulticols}%
}
\newcommand{\question}[2]{%
    \refstepcounter{exquestion}%
    \label{ex.\arabic{exblock}.\arabic{exquestion}}%
    \item #1%
    \addtostream{solutions}{\noexpand\item[\noexpand\ref{ex.\arabic{exblock}.\arabic{exquestion}}.] #2}%
}
\setlist*[questionlist]{font=\bfseries}
\setlist*[solutionlist]{noitemsep,font=\bfseries}
%%%%%%%%%%%%%%%%
%%%%%%%%%%%%%%%%%%%%%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%
\begin{document}
\chapter{فصل اول}\label{ex.\arabic{chapter}}
\ptext[1-2]
\exheader
\begin{exercisescol}[noitemsep]{2}
   \question{
$\int\sqrt{x}dx$}{$\tfrac{2}{3}x\sqrt{x}+C$}
    \question{$\int3e^xdx$}{$3e^x+C$}
    \question{$\int(3x^2-\sqrt{5x}+2)dx$}{$x^3-\tfrac{2}{3}x\sqrt{5x}+2x+C$}
    \question{$\int(\tfrac{1}{2x}-\tfrac{2}{x^2}+\tfrac{3}{\sqrt{x}})dx$}{$\tfrac{1}{2}\ln|x|+\tfrac{2}{x}+6\sqrt{x}+C$}
    \question{$\int\sqrt{x}dx$}{$\tfrac{2}{3}x\sqrt{x}+C$}
    \end{exercisescol}
    \ptext[1]
    \exheader
\begin{exercisescol}[noitemsep]{2}
   \question{
$\int\sqrt{x}dx$}{$\tfrac{2}{3}x\sqrt{x}+C$}
    \question{$\int3e^xdx$}{$3e^x+C$}
    \question{$\int(3x^2-\sqrt{5x}+2)dx$}{$x^3-\tfrac{2}{3}x\sqrt{5x}+2x+C$}
    \question{$\int(\tfrac{1}{2x}-\tfrac{2}{x^2}+\tfrac{3}{\sqrt{x}})dx$}{$\tfrac{1}{2}\ln|x|+\tfrac{2}{x}+6\sqrt{x}+C$}
    \question{$\int\sqrt{x}dx$}{$\tfrac{2}{3}x\sqrt{x}+C$}
    \end{exercisescol}
   \chapter{فصل دوم}\label{ex.\arabic{chapter}}
\exheader
\begin{exercisescol}[noitemsep]{2}
   \question{
$\int\sqrt{x}dx$}{$\tfrac{2}{3}x\sqrt{x}+C$}
    \question{$\int3e^xdx$}{$3e^x+C$}
    \question{$\int(3x^2-\sqrt{5x}+2)dx$}{$x^3-\tfrac{2}{3}x\sqrt{5x}+2x+C$}
    \question{$\int(\tfrac{1}{2x}-\tfrac{2}{x^2}+\tfrac{3}{\sqrt{x}})dx$}{$\tfrac{1}{2}\ln|x|+\tfrac{2}{x}+6\sqrt{x}+C$}
    \question{$\int\sqrt{x}dx$}{$\tfrac{2}{3}x\sqrt{x}+C$}
\end{exercisescol}
\chapter{فصل سوم}\label{ex.\arabic{chapter}}
\exheader
\begin{exercisescol}[noitemsep]{2}
   \question{
$\int\sqrt{x}dx$}{$\tfrac{2}{3}x\sqrt{x}+C$}
    \question{$\int3e^xdx$}{$3e^x+C$}
    \question{$\int(3x^2-\sqrt{5x}+2)dx$}{$x^3-\tfrac{2}{3}x\sqrt{5x}+2x+C$}
    \question{$\int(\tfrac{1}{2x}-\tfrac{2}{x^2}+\tfrac{3}{\sqrt{x}})dx$}{$\tfrac{1}{2}\ln|x|+\tfrac{2}{x}+6\sqrt{x}+C$}
    \question{$\int\sqrt{x}dx$}{$\tfrac{2}{3}x\sqrt{x}+C$}
\end{exercisescol}
\chapter{پاسخ تمرینات}
\printsolutions
\end{document}