これが故障です：
* ナトリウム（Na） is a metallic element 。 It's a soft, silvery-white alkali metal.
* 水素（H） is a nonmetallic element 。 It's the lightest and most abundant element in the universe.
* 炭素（c） is a nonmetallic element 。 It's a versatile element that forms the basis of organic chemistry.
* 酸素（O） is a nonmetallic element 。 It's a highly reactive element and is essential for life.
Therefore, baking soda is a compound made up of both metallic and nonmetallic elements.
