Need help to solve the questions from sheet thanks

the answer for sodium is 0.186

the answer for rubidium is 0.251

colorless gas, exhibiting a blue glow when placed in an electric field

b) solid

its a type of rock

answer is: nuclear fusion produces elements that are heavier than helium.

nuclei combine to form a heavier nucleus, releasing energy.  

for example, fusion of hydrogen atoms at the sun.  

this fusion nuclear reaction is in the inner core of the sun and hydrogen (atomic number 1) is conveted into helium (atomic number 2).  

the inner core is the central region of the sun and all solar energy is produced in the core by nuclear fusion.