In a document i chose the font Heading 1 + left for chapters , so i
have chapter 1, chapter 2..., i have titles below those lines,
though i use the same font for all, for some chapters the difference
between the line "chapter x" and the title is more than in other cases,

also for these lines when i generate the TOC, i get two lines e.g.,
"chapter 1................1
Background...............1"
for others i get in one line e.g., "chapter 2 Introduction......"
can i know why this might be happening.