For main keyword Mobile phone What is the best for SEO,optimizing Mobile phone or Mobile phones will have more chances to work well with two forms (mobile phone and mobile phones)
i would go for whatever sounds best. for e.g. buy mobile phone wouldnt sound right or buy a mobile phones wouldnt sound right. does ur site sell a mobile phone or does it sell mobile phones.
Whichever gets more searches and has less competition. They are distinct in the eyes of the search engines.
same idea. i just grabbed > "city name" PropertyListings.com (with S) the singular was available. but the PLAN is a site with SEVERAL listings, so the singular didn't make as much sense to me. i guess in a perfect world, grab both. i just didn't see the need. IMHO
In search results, the SERPs could be different when websites that are promoting either keywords. But once your site becomes authoritive, whichever of those keywords you choose don't really matter. Google picks up singular keywords when you promoting plural ones. So, it is not too big deal unless you want to rank high quickly to see a result in SERPs. But the both keywords you selected are extremely competitive. They are too general to use as a keyword. I hope you brought that up an example.
If they are cmpetive words, I believe the SERPS would be different. If so, make a page targeting singular & another targeting plural (without duplicating content)