Question

The halogen which is liquid at room temperature is:
A. Fluorine
B. Astatine
C . Bromine
D. Iodine

Answer 1

Hint: To answer this question the periodic properties of the elements from different groups should be known. The periodic properties have opposite trends between left to right and top to bottom. Halogens are from group 18. Which is on the right side of the periodic table.

Complete step by step solution:
Halogens are the most electronegative atoms of each period of the periodic table. Top to bottom of the halogen group size increases because the number of electrons as well as number of shells increases. Now with increasing the number of shells their atomic mass is also increased. Due to the high atomic mass of the bottom elements of this group , the physical state of the bottom elements is solid at room temperature. And due to low molecular mass top elements are in gaseous state at room temperature.
Now the top element of this group is Fluorine , chlorine. And bottom elements are Astatine and Iodine
But bromine is in the middle of the group and also the molecular mass of the form is not large to be solid as well as low to be gas. Due to this reason the physical state of bromine is liquid at room temperature.

So, the correct option is C.

Note: Due to high atomic mass of the bottom elements of this group , the physical state of the bottom elements is solid at room temperature. And due to low molecular mass top elements are in gaseous state at room temperature. But bromine is in the middle of the group and also the molecular mass of the form is not large to be solid as well as low to be gas. Due to this reason the physical state of bromine is liquid at room temperature.