We present results on the X(3872), produced in $B^+ to X(3872) K^+$ and $B^0 to X(3872) K^0_S$ decays where $X(3872) to J/psi pi^+ pi^-$. We report the first statistically significant observation of $B^0 to X(3872) K^0_S$ and measure the ratio of branching fractions to be $frac{{cal B}(B^0 to X(3872)K^0)} {{cal B}(B^+ to X(3872)K^+)} = 0.82 pm 0.22 pm 0.05$, consistent with unity. The mass difference between the X(3872) states produced in $B^+$ and $B^0$ decay is found to be $delta M equiv M_{XK^+} - M_{XK^0} = (+0.18 pm 0.89 pm 0.26)$ MeV/$c^2$, consistent with zero. In addition, we search for the X(3872) in the decay $B^0 to X(3872)K^+pi^-$, $X(3872) to J/psi pi^+ pi^-$. We measure ${cal B}(B^0 to X(3872) (K^+ pi^-)_{NR}) times {cal B}(X(3872) to J/psi pi^+ pi^-) = (8.1 pm 2.0 ^{+1.1}_{-1.4})times 10^{-6}$ and we set the 90% C.L. limit, ${cal B}(B^0 to X(3872)K^{*}(892)^0) times {cal B}(X(3872) to J/psi pi^+ pi^-) < 3.4 times 10^{-6}$. The analysis is based on a 605 fb$^{-1}$ data sample collected at the $Upsilon(4S)$ with the Belle detector at the KEKB collider.
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