This is a problem from a book which I expanded on. Black 2 is actually a tesuji, and the best one to punish white in this situation.
(;AB[rr]AB[rq]AB[qq]AB[pp]AB[op]AB[np]AB[jq]AB[jo]AW[rs]AW[qr]AW[ps]AW[pq]AW[oq]AW[or]AW[lq]AB[mr]LB[lq:1]LB[mr:2]C[White played 1, which was a mistake, and black punished white with 2. Help white respond to 2 as best as possible.]AB[qo]AB[mn]AB[kn]AB[ir]AP[goproblems]
(;W[nr]
(;B[mq]
(;W[ns]C[Good, this is simple and best, because the stone at 1 was lost anyway.RIGHT])
(;W[ms];B[ns])))
(;W[mq];B[nr];W[nq];B[lr])
(;W[lr];B[mq]
(;W[ns];B[nr];W[ms];B[kr]C[Very bad for white.])
(;W[nr];B[ns]C[White is dead.]))
(;W[nq];B[mq];W[mp];B[lp]
(;W[lr];B[mo])
(;W[nr];B[ns])
(;W[ns];B[nr];W[lr];B[mo];W[ms];B[mp]))
(;W[ns];B[nr];W[nq];B[mq])
(;W[ms];B[mq]
(;W[nr];B[ns])
(;W[lr];B[ns])
(;W[ns];B[nr];W[lr];B[kr]))
(;W[ls];B[nr]
(;W[nq];B[mq];W[mp];B[lp])
(;W[ns];B[nq]
(;W[lr];B[ms])
(;W[ms];B[lr]))
(;W[mq];B[nq])))