Question

Which of the following is a physical change?

A) Condensation forms on cold glass.
B) Glass reacts with hydrofluoric acid.
C) A ground glass joint slowly forms sodium silicate when exposed to NaOH.
D) Cobalt salts dissociate in a piece of blue stained glass.
E) Silica is hydrated, forming silicic acid.

Answer 1

The physical change among the options given is 'A) Condensation forms on cold glass,' as it is merely a change of state from gas to liquid without the formation of new substances.

Step-by-step explanation:

The question at hand is about categorizing a process as a physical change. Among the options provided, the process described in 'A) Condensation forms on cold glass' represents a physical change. Condensation is a change of state from gas to liquid and does not result in the formation of new chemical substances. This is in contrast to chemical changes which involve the making or breaking of chemical bonds, leading to new substances.

Other options such as the reaction of glass with hydrofluoric acid, the ground glass joint forming sodium silicate when exposed to NaOH, and silica forming silicic acid when hydrated, all involve chemical reactions and the creation of new substances, which are indicative of chemical changes.