بسم الله الرحمن الرحيم
(Fatwa: 1664/1330/B=12/1434)
Yes, it is alright to give laccha of 20 gram gold as mahr, but it is not necessary to tie poth on bride’s neck during nikah ceremony, you can also make her wear the same after later.
Allah knows Best!
Darul Ifta,
Darul Uloom Deoband
