A parent DNA molecule with both strands labeled with light nitrogen (${}^{14}N$) is transferred to a growth medium containing only heavy nitrogen (${}^{15}N$) as the sole nitrogen source, and allowed to undergo three rounds of semiconservative replication.

Which of the following statements correctly predict the results?

1. After one round of replication, 100% of the DNA molecules are hybrid (${}^{14}N{/}^{15}N$).
2. After two rounds of replication, 50% of the DNA strands present in the population contain ${}^{14}N$.
3. After three rounds of replication, the ratio of heavy-density DNA molecules (${}^{15}N{/}^{15}N$) to intermediate-density DNA molecules (${}^{14}N{/}^{15}N$) is $3:1$.