How to validate flat XML document?

Is there a tool or command to check if my flat XML document have any syntax/semantic errors?

Is this xml are in xml flat format?

<soapenv:Envelope xmlns:soapenv=“http://schemas.xmlsoap.org/soap/envelope/” xmlns:res=“http://xxx”>
soapenv:Header/
soapenv:Body
res:buscarScoreMaiorSeveridade



0136

43434434

</res:buscarScoreMaiorSeveridade>
</soapenv:Body>
</soapenv:Envelope>