Is calcium carbonate chemical change ?

Calcium oxide is known as lime and is one of the top 10 chemicals produced annually by thermal decomposition of limestone. .Over time, this reacts with carbon dioxide in the air to form crystals of calcium carbonate, which lock the sand grains together to form a hard rock-like material.

answer: e.   sour taste

explanation: acids are those substances which dissociates in water to give ions. as they dissociate to give ions, they act as electrolytes and thus are electrically conductive. acids are sour in taste. example: hcl

bases are those substances which dissociates in water to give ions or accepts ions. as they dissociate to give ions, they act as electrolytes and thus are electrically conductive. bases are bitter in taste. bases are slippery in nature.

i just calculated it all out, and not including weekends, and all the different days off. as of this school year (2018-2019) students are spending 2198 hours in school this year