Celery, how to specify queue for both header and body using chords (header is a chunked group)

Question

I have an issue with my chord. Here is in pseudocode:

@app.task(queue="a")
def a(p1, p2):
  ...
@app.task(queue="b")
def b(*args, **kwargs):
  ...

chunks = a.chunks(([1,2],[2,3],), 1)
g = chunks.group()

c = chord(g)(b.s())

This code will make a tasks run on default delery queue. How can I indicate that I want these tasks running on a queue?