The number of ways in which 3 boys and 2 girls can sit on a bench so that no two boys are adjacent is ______

As no two boys can sit together their arrangement will be $\mathrm{B} \mathrm{G} \mathrm{B} \mathrm{G} \mathrm{B}$

Boys will be arranged first and then girls will sit in between them.

The number of ways of arranging boys will be $3!=3\times 2\times 1=6$

And, number of ways of arranging girls will be $2!=2\times 1=2$

Therefore, total number of ways they can be arranged will be $=6\times 2=12$