# How to align chapter label on right side and chapter title on left side

I want to align the Chapter Label on right side of the page and chapter title on left side of the page. How can I do this following command:

\chapter{Introduction}


The output should be like this

• Please tell us (a) which document class you employ and (b) which packages -- if any -- that can help modify the appearance of headers (such as chapter headers) you load. – Mico Sep 28 at 5:36

It's not hard with titlesec:

\documentclass[12pt, a4paper]{book}%

\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\usepackage{lmodern}
\usepackage{lipsum}
\usepackage{titlesec}%

\titleformat{\chapter}[display]{\sffamily\huge\bfseries}{\filleft\chaptername \thechapter}{4ex}{}[{\titlerule[1.5pt]}]

\begin{document}

\chapter{Introduction}
\sffamily
\lipsum[11]

\end{document}