Answer:
free-living (nonsymbiotic) bacteria,
Explanation:
Rules for Numbers WITHOUT a Decimal Point
START counting for sig. figs. On the FIRST non-zero digit.
STOP counting for sig. figs. On the LAST non-zero digit.
Non-zero digits are ALWAYS significant.
Zeroes in between two non-zero digits are significant. All other zeroes are insignificant.
Answer is "A".
Explanation;
Physical changes mean an arrangement of particles of a given substance without producing new substance but changes in physical form of the substance.
<em>Example :</em> vaporization of water ( water goes its gaseous phase from liquid form).
Chemical changes mean an arrangement of particles while forming new substance.
<em>Example : </em>heating of CaCO₃. (In this process CaO and CO₂ are formed).
In this problem, the volume of water has decreased. Hence, it can be said that this is an example of physical changes due to not forming of new substance.