Question

What group contains a solid ,liquid and gas at room temperature

Answer 1

Answer:

group 7

Explanation:

fluorine and chlorine are gases at room temp

bromine is liquid at room temp

iodine and astatine are solid at room temp

they are all in group 7

Answer 2

Answer:

Group 17 or VIIA which consists of Halogens have elements existing in solid, liquid and gas at room temperature (20 degree celcius).

Explanation:

Fluorine, Chlorine, bromine, Iodine and Astatine are the halogens we know.

At room temperature,

Fluorine and chlorine are gases,

Bromine is a liquid and  

Iodine and Astatine are solids.

Halogens are called as Salt producer.

They are diatomic elements except Astatine with a subscript 2 which represents a molecule of halogen is comprised of two halogen atoms $(F_2,Cl_2,Br_2,I_2 and At)$

The general electronic configuration of halogen is $ns^2np^5$

The elements present in the same group will have same number of valence electrons (outer shell electrons)

For example  

Fluorine, Chlorine, Bromine are all present in the same Group

The electronic configurations  are  

$F-9\Rightarrow1s^2 2s^2 2p^5$

$Cl-17\Rightarrow1s^2 2s^2 2p^6 3s^2 3p^5$

$Br-35\Rightarrow1s^2 2s^2 2P^6 3s^2 3p^6 4s^2 3d^{10} 4p^5$

Hence all these elements have similar chemical properties since it depends on the electrons present in an element.