Installed 16.04. installed 'apache2'. installed 'php', it gave me php7.0. But now my existng web pages with dot+php extensions are not being pre-processed by apache2.
I had a similar problem years ago with php5 and had to edit php.ini. But php 7.0 seems to have no php.ini file. html web pages are OK, but php web pages are blank.
Simplest test file is system("hostname"); which shows the machine name under 12.04/php5 but a blank screen under 16.04/php7.0.