Chinese is not the most spoken language. IIRC India has a larger population now than China *one baby per family rule has taken effect* so I guess Hindu would beat them anyway and does not Bangladesh speak Hindu as well as Bengali and English? And also Fijians who speak Hindu and English.
However a large percentage of the educated Indians speak English and with the USA,NZ,OZ,PNG many African countries like Kenya, South Africa, Nigeria ect and hundreds of pacific and Atlantic islands, hey even parts of Canada
And when you take into account all the people who learn English as a second language then is no doubt as to which is the most spoken language in the world.
As to which is the most widely spoken language in Europe? hmmmm could Russian be a contender? Either way English is well beaten by German and French.
Just a side question. Is Spanish not the second most spoken language in the world? I’m betting that it may beat Hindu and leave China (mandarin) in a low 4th spot!