Where I find mimeapps.list?

It should be in below directory:

/usr/share/applications/mimeapps.list

If its not be exists, you can create it, and put that line into this file:

sudo nano /usr/share/applications/mimeapps.list

Also you can create this file in your home directory:

nano ~/.local/share/applications/mimeapps.list

And put this line into that file:

application/vnd.nokia.qt.qmakeprofile=qtcreator.desktop

For example my mimeapps.list file content is:

$ cat /usr/share/applications/mimeapps.list
[Default Applications]
application/wps-office.et=/usr/share//applications/wps-office-et.desktop
application/wps-office.ett=/usr/share//applications/wps-office-et.desktop
application/wps-office.xls=/usr/share//applications/wps-office-et.desktop
application/wps-office.xlt=/usr/share//applications/wps-office-et.desktop
application/vnd.ms-excel=/usr/share//applications/wps-office-et.desktop
application/msexcel=/usr/share//applications/wps-office-et.desktop
application/wps-office.xlsx=/usr/share//applications/wps-office-et.desktop
application/wps-office.xltx=/usr/share//applications/wps-office-et.desktop
vnd.ms-excel.sheet.macroenabled.12=/usr/share//applications/wps-office-et.desktop
vnd.ms-excel.template.macroenabled.12=/usr/share//applications/wps-office-et.desktop
application/wps-office.dps=/usr/share//applications/wps-office-wpp.desktop
application/wps-office.dpt=/usr/share//applications/wps-office-wpp.desktop
application/wps-office.ppt=/usr/share//applications/wps-office-wpp.desktop
application/wps-office.pot=/usr/share//applications/wps-office-wpp.desktop
application/vnd.ms-powerpoint=/usr/share//applications/wps-office-wpp.desktop
application/vnd.mspowerpoint=/usr/share//applications/wps-office-wpp.desktop
application/powerpoint=/usr/share//applications/wps-office-wpp.desktop
application/wps-office.pptx=/usr/share//applications/wps-office-wpp.desktop
application/wps-office.potx=/usr/share//applications/wps-office-wpp.desktop
vnd.ms-powerpoint.presentation.macroenabled.12=/usr/share//applications/wps-office-wpp.desktop
vnd.ms-powerpoint.template.macroenabled.12=/usr/share//applications/wps-office-wpp.desktop
application/wps-office.wps=/usr/share//applications/wps-office-wps.desktop
application/wps-office.wpt=/usr/share//applications/wps-office-wps.desktop
application/wps-office.doc=/usr/share//applications/wps-office-wps.desktop
application/wps-office.dot=/usr/share//applications/wps-office-wps.desktop
application/vnd.ms-word=/usr/share//applications/wps-office-wps.desktop
application/msword=/usr/share//applications/wps-office-wps.desktop
application/msword-template=/usr/share//applications/wps-office-wps.desktop
wps-office-doc.png=/usr/share//applications/wps-office-wps.desktop
wps-office-dot.png=/usr/share//applications/wps-office-wps.desktop

For more information about MIME type default applications, please look at this link in Arch linux Wiki.