Doubt from thermochemistry

@Shaquib @Achyut_2020 @akash_2020 help pls..

Bro why has the entire setup compared to water..I know that the conditons have been given so we can assume it but HCl also remains in the solution after the reaction...what if conditions kuch alag something which doesn't match with properties of h2o??? Pls correct me if I am wrong..

Heat evolved due to neutralization reaction.