I want to check that AdMob is working or not
when i was previewing my game then no advts are showing
How are you previewing your game? You can't see Ads on PC or Mac, it has to run from a Device. You can try enabling the Test Mode to see if Test ads are appearing.
I am testing it on Chrome Browser and Test mode is enabled
but NO Ad is showing
Develop games in your browser. Powerful, performant & highly capable.
Like I said, you cant see Ads on your PC browser. Even with Test Mode enabled. It has to run from a Device.
Try building an APK and test it on your Android phone/tab