Answer:- C. decrease in temperature.
Explanations:- Solubility of a solid increases if the pressure is increased as the high pressure helps the solid to get dissolved in the solvent.
If the surface area of the solute is increased then more and more solute comes into the contact of the solvent and the solubility increases.
If the stirring is increased then it also helps the solute to get dissolved into the solvent.
Solubility of solids is directly proportional to the temperature.
So, if the temperature is decreased then solubility of the solute is also decreased.
The radiation source that provides the greatest radiation dose is one year of natural background radiation.
Answer: 
: Pure substance, Element
: Pure substance , Element
: Pure substance, Compound
Explanation:
Element is a pure substance which is composed of atoms of similar elements.It can not be decomposed into simpler constituents using chemical reactions.Example: 
and
Compound is a pure substance which is made from atoms of different elements combined together in a fixed ratio by mass.It can be decomposed into simpler constituents using chemical reactions. Example:
Heterogeneous Mixture : Mixture that has its different components mixed unevenly within the substance
. Example: Air
Homogeneous Mixture : Mixture that has its different components mixed evenly within the substance. Example: sugar dissolved in water
The boiling point of chloroform is 61.2 C or 142.2 F. Please mark as brainliest if this helped you out :).
