Answer:
elements in the same column have the same number of neutrons. elements with similar mass are placed in the same column.
Answer:
A. Sulfur _________ group 16 chalcogens
B. Sodium _________ group 1 alkali metals
C. Argon _________ group 18 noble gases
D. Silicon _________ group 14 carbon family
E. Chlorine _________ group 17 halogens
F. Phosphorus_________ group 15 pnicogens
Answer:
51.94°
Explanation:
= Unpolarized light
= Light after passing though second filter = 
Polarized light passing through first filter

Polarized light passing through second filter

The angle between the two filters is 51.94°
Answer:
option E
Explanation:
given,
diameter = 4 mm
shutter speed = 1/1000 s
diameter of aperture = ?
shutter speed = 1/250 s
exposure time to the shutter time

N is the diameter of the aperture and t is the time of exposure
now,


inserting all the values

N₂² = 4
N₂ = 2 mm
hence , the correct answer is option E