unit cell Dimensions when 2*theta=40.0 is (100) where sin^2(theta)/0.0111 is 1
unit cell Dimensions when 2*theta=58.0 is (110) where sin^2(theta)/0.0111 is 2
unit cell Dimensions when 2*theta=73.0 is (111) where sin^2(theta)/0.0111 is 3
unit cell Dimensions when 2*theta=86.8 is (200) where sin^2(theta)/0.0111 is 4
unit cell Dimensions when 2*theta=100.4 is (210) where sin^2(theta)/0.0111 is5
unit cell Dimensions when 2*theta=114.7 is (211) where sin^2(theta)/0.0111 is 6
The ratio of sin(theta)^2 values for first and second angles is 0.50
 Hence the crystal structure is bcc
Lattice constant a=0.318nm 
 And the element is tungsten Since Tungsten has lattice constant of 0.318nm and crystallizes in bcc structure 