does job advertisement is invitation to offer?

Hello sir, 

Yes, it is true that job advertisement is just invitation to offer and not offer. In an invitation to offer, no specific party has the intention to enter into a contract. The seller may enter into a contract with anybody from the public who makes the best offer to him. So, the essence of an invitation to offer is that the offer is actually made by the seller.

An invitation to offer ‘evolves’ into a contract in a different manner than an offer. Initially, it is an invitation to offer, say by a display of goods and their prices. When a person makes an offer that is good enough and the seller ‘accepts’ it, it becomes a contract. Unlike offer, which is made by the seller to the buyer.  

With respect to sending resumes being an offer, i don't agree with this. This is because in case of an employment process, once a resume has been selected, the next step is a job offer by the employer, acceptance of which by the employee results in a contract.  

I hope this helps.

Thank you.