# I want to set full page instead of using two columns? [closed]

I am writing a solution manual which I have already completed. I want the normal page to write the preface, acknowledgement and dedication just as the page on which contents are written without splitting into columns. I do not know how to set the page normally to write the preface. I am providing full files with all codes.

\documentclass[10pt]{book}
\usepackage[paperheight=9in,paperwidth=7in, top=1in, bottom=0.8in, twocolumn, twoside]{geometry}
\setlength{\columnseprule}{0.4pt}
\usepackage{amssymb}
\usepackage{mathrsfs}
\usepackage[centertags]{amsmath}
\usepackage{amsthm}
\newtheorem{theorem}{Theorem}
\usepackage{epsfig}
\usepackage{graphicx}\graphicspath{{Graphics/}}
\usepackage{amsthm}
\usepackage{mathptmx}
\usepackage[square,sort&compress]{natbib}
\usepackage{pgf,tikz,pgfplots}
\pgfplotsset{compat=1.15}
\usetikzlibrary{arrows}
\usepackage[T1]{fontenc}
\usepackage{fancyhdr}\pagestyle{fancy}
\usepackage{xcolor}
\usepackage{setspace}
\usepackage{booktabs}
%\usepackage{hyperref}
\usetikzlibrary{arrows.meta}
\renewcommand{\baselinestretch}{1.5}
\newcommand\aug{\fboxsep=-\fboxrule\!\!\!\fbox{\strut}\!\!\!}
\theoremstyle{definition}
\newtheorem{Thm}{Theorem}[section]
\newtheorem{lem}[Thm]{Lemma}
\newtheorem{pro}[Thm]{Proposition}
\newtheorem{de}[Thm]{Definition}
\newtheorem{re}[Thm]{Remark}
\newtheorem{ex}[Thm]{Example}
\newtheorem{cor}[Thm]{Corollary}
\numberwithin{equation}{section}
\definecolor{uuuuuu}{rgb}{0.26666666666666666,0.26666666666666666,0.26666666666666666}
\begin{document}
%\include{Frontmatter/colophon}
\tableofcontents
%\Mainmatter
\include{Mainmatter/Chapter-1}
\end{document}


I need the preface page like the contents page without splitting into two columns. I need two columns geometry just after the contents table. How can I set this.

Put \onecolumn when you want one column and \twocolumn when you want two columns

% onetwocolprob2.tex  SE 555696
\documentclass[10pt]{book}

\usepackage[paperheight=9in,paperwidth=7in, top=1in, bottom=0.8in, twocolumn, twoside]{geometry}
\setlength{\columnseprule}{0.4pt}
\usepackage{amssymb}
\usepackage{mathrsfs}
\usepackage[centertags]{amsmath}
\usepackage{amsthm}
\newtheorem{theorem}{Theorem}
\usepackage{epsfig}
\usepackage{graphicx}\graphicspath{{Graphics/}}
\usepackage{amsthm}
\usepackage{mathptmx}
\usepackage[square,sort&compress]{natbib}
\usepackage{pgf,tikz,pgfplots}
\pgfplotsset{compat=1.15}
\usetikzlibrary{arrows}
\usepackage[T1]{fontenc}
\usepackage{fancyhdr}\pagestyle{fancy}
\usepackage{xcolor}
\usepackage{setspace}
\usepackage{booktabs}
%\usepackage{hyperref}
\usetikzlibrary{arrows.meta}
\renewcommand{\baselinestretch}{1.5}
\newcommand\aug{\fboxsep=-\fboxrule\!\!\!\fbox{\strut}\!\!\!}
\theoremstyle{definition}
\newtheorem{Thm}{Theorem}[section]
\newtheorem{lem}[Thm]{Lemma}
\newtheorem{pro}[Thm]{Proposition}
\newtheorem{de}[Thm]{Definition}
\newtheorem{re}[Thm]{Remark}
\newtheorem{ex}[Thm]{Example}
\newtheorem{cor}[Thm]{Corollary}
\numberwithin{equation}{section}
\definecolor{uuuuuu}{rgb}{0.26666666666666666,0.26666666666666666,0.26666666666666666}
\begin{document}

%\include{Frontmatter/colophon}
Some front matter. \lipsum   %%% added
\tableofcontents
%\Mainmatter