in solutions of bills of exchange of dk goel accountany , everywhere cash account is written but in book its bank account.please tell me which one is correct?????

Surrender, in case of bills of exchange, usually Bank A/c is used, when bill is discounted with bank or sent to bank for collection and in the remaining cases Cash A/c is used. 
However, you can follow anyone of them. Both are correct. Else, you can also write Cash/Bank A/c if question is silent regarding the mode of payment/receipt i.e. in cash or through cheque.