Which elements normally exist in the liquid state?
A.Iodine and mercury
B.Mercury and chlorine
C.Bromine and iodine
D.Bromine and mercury

Hint: There are about 118 elements in the periodic table out of which most of the elements are metals. Any element would exist in the liquid state at room temperature when its freezing point is below \[{\text{25}}{{\text{ }}^{\text{0}}}{\text{C}}\], which is the normal room temperature.

Complete answer:
The freezing point of a substance is defined as that temperature at which a liquid material gets converted into the solid phase. At this temperature the strength of adhesion between the molecules of a substance are strong enough to keep them bound as a solid material. This temperature is the same as the melting point of the solid.
Among the periodic table, most of the elements are solid are room temperature which the exception to mercury which solidifies at \[ - {39^{\text{0}}}{\text{C}}\], gallium which melts at \[ - {30^{\text{0}}}{\text{C}}\], and bromine which solidifies at \[ - {\text{7}}{{\text{ }}^{\text{0}}}{\text{C}}\]. At temperatures higher than this the elements remain liquid.
The freezing points of the above elements are: \[{\text{113}}{\text{.7}}{{\text{ }}^{\text{0}}}{\text{C}}\] for iodine, \[ - {38.33^{\text{0}}}{\text{C}}\] for mercury, \[ - {101.5^{\text{0}}}{\text{C}}\] for chlorine, and \[ - {7.2^{\text{0}}}{\text{C}}\] for bromine.

Hence, the correct combination of elements is Bromine and mercury, which is option D.

Note:
Besides these there are some other elements in the periodic table, which are present in the liquid state at room temperature. Caesium is one such element whose melting point is \[{\text{28}}{\text{.40}}{{\text{ }}^{\text{0}}}{\text{C}}\] so it remains more or less in the molten state only at room temperatures.
Besides these there are other elements that exist at room temperature including the halogen gases, the noble gases, etc.