If the amount collected to build a mosque is not enough
Question

                We have a donation of 20,000 riyals for building a mosque. If this amount is not enough to build a mosque, is it permissible to use this money for other projects, or can it be contributed to build part of a mosque or to repair an existing mosque?
Praise be to Allah.You have to look for a mosque for which this amount will be enough, 
even if that is outside the Kingdom (i.e., Saudi Arabia). If you cannot 
find anything, you can contribute it towards the building of a mosque, 
such as buying the land or some of the construction materials, etc.  
In this way the person who donated it will attain the reward. And Allaah 
knows best.