$\overrightarrow{ F }= Q \overrightarrow{ E }+ Q (\overrightarrow{ V } \times \overrightarrow{ B })$

$=\left(1.6 \times 10^{-19}\right)\left(10 \hat{ i } \times 10^{-6}\right)+\left(1.6 \times 10^{-19}\right)[(2 \hat{ i }) \times(\hat{ i }+3 \hat{ j }+4 \hat{ k })] \times 10^{-9}$

$=\left(1.6 \times 10^{-19}\right)[10 \hat{ i }-8 \hat{ j }+6 \hat{ k }] \times 10^{-6} N$

Calculate the acceleration as follows,

$\overrightarrow{ a }=\frac{\left(1.6 \times 10^{-19}\right)[10 \hat{ i }-8 \hat{ j }+6 \hat{ k }] \times 10^{-6} N }{1.6 \times 10^{-27}}$

$=1400 m / s ^{2}$