Do change that cannot be easily reversed, such ad burning, observe the law of conservation of mass? explain

Yes

Explanation:

All chemical processes must obey the Law of Conservation of Mass.

The burning of paper appears to disobey this law. The paper disappears in flame, leaving only a small amount of ash.

Paper(s) + O₂(g) ⟶ CO₂(g) + H₂O(g) + ash (s)

However, that’s because the main products, carbon dioxide and water vapour, are invisible gases.

Nevertheless,

mass of (paper + oxygen) = mass of (CO₂ + O₂ + ash)

14,16 18 reacts with group

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.