You mobile signal is poor and that will make a heavy demand on the battery. Your WiFi is also on all the time, which, unless intentional, suggests that something may going on in the background that you are not aware of. The first thing to do is to make sure all your basic settings, for Location, Syncing and so on, are sensibly set. Review this guide by B. Diddy:
It would also be useful to have a screenshot of the stats showing battery consumption app-by-app....Screen normally tops the list. If Android OS or Google Play Services or a similar app are using abnormally high charge, as they occasionally do, that again may indicate something going on in the background which may need to be stopped or limited.
Re: i bought nexus 5 on last monday my battery draining soo fast what should i do?
Welcome to AC! First of all, the Nexus 5 isn't known for good battery life, so it's not like you should expect THAT good of battery life.
Second, mobile signal isn't very good, so that will put quite some demand on battery.
And third, it's a new phone and as such, a new battery. It takes about 7 days for the battery to be able to use its full capacity, so do wait before making the final call.
Also, I'd recommend installing the apps ShutApp and Doze, which will help boost standby battery. Super useful.