Income Tax Query. Capital gain & section 54

In case the assessee has purchased a flat. Full consideration for flat has been paid by assessee only , however on sale deed assessee included his wife name also as purchaser no. 2 & the property is jointly held by them as per deed. Now if the assessee is selling a property then capital gain is chargeable equally in the hands of husband & wife OR full capital gain will taxable in the hands of husband only since the wife contribution is nil at the time of acquisition ?
2nd Query is
From FY 2019 20 incase the capital gain is upto 2 crore rupees then exemption us 54 can be claim for 2 properties. But this exemption only once in a lifetime. It means if I take this exemption now for 2 properties then suppose after 5 years can I take exemption us 54 for one property or no more exemption us 54 in lifetime ?