下列运算正确的是 ( )
(1) $\sqrt{12}=2 \sqrt{3}$
(2) $\sqrt{\frac{3}{2}}=\frac{\sqrt{3}}{2}$
(3) $(5-2 \sqrt{3})(5+2 \sqrt{3})=25-2 \times 3=19$,
$(2 \sqrt{10}-\sqrt{5}) \div \sqrt{5}=2 \sqrt{2}-1 ;$
( 1 ) $\sqrt{12}=\sqrt{4 \times 3}=2 \sqrt{3}$, 故 (1)正确;

(2) $\sqrt{\frac{3}{2}}=\sqrt{\frac{3 \times 2}{2 \times 2}}=\frac{\sqrt{6}}{2}$, 故 (2) 错误;

(3) $(5-2 \sqrt{3})(5+2 \sqrt{3})=25-4 \times 3=13$, 故(3)错误;

(4) $(2 \sqrt{10}-\sqrt{5}) \div \sqrt{5}=2 \sqrt{10} \div \sqrt{5}-\sqrt{5} \div \sqrt{5}=2 \sqrt{2}-1$, 故(4)正确;

故选 $C$.