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A two-way communication using message queue in C can be implemented as follows:

1. Create two message queues, one for sending messages from Sender to Receiver and another for sending messages from Receiver to Sender.

int mq_sender_to_receiver = mq_open("/sender_to_receiver", O_CREAT | O_RDWR, 0666, NULL);
int mq_receiver_to_sender = mq_open("/receiver_to_sender", O_CREAT | O_RDWR, 0666, NULL);

1. Fork a child process, which will act as the Sender and the parent process will act as the Receiver.

pid_t pid = fork();

1. In the child process (Sender), use mq_send() to send a message to the Receiver.

char msg[100] = "Hello, Receiver!";
mq_send(mq_sender_to_receiver, msg, 100, 0);

1. In the parent process (Receiver), use mq_receive() to receive the message from the Sender.

char msg[100];
mq_receive(mq_sender_to_receiver, msg, 100, NULL);

1. In the parent process (Receiver), use mq_send() to send a message to the Sender.

char response[100] = "Hello, Sender!";
mq_send(mq_receiver_to_sender, response, 100, 0);

1. In the child process (Sender), use mq_receive() to receive the message from the Receiver.

char response[100];
mq_receive(mq_receiver_to_sender, response, 100, NULL);

1. Print the messages received by both processes.

if (pid == 0) {
    // Sender process
    printf("Sender received: %s\n", response);
} else {
    // Receiver process
    printf("Receiver received: %s\n", msg);
}

1. Finally, close and unlink the message queues. ``` mqclose(mqsendertoreceiver); mqclose(mqreceivertosender); mqunlink("/sendertoreceiver"); mqunlink("/receivertosender");