Match the following.

1. to bend
-
opaque
-
2. not allowing light to pass through
-
refract
-
3. only partially clear
-

translucent
4. clear
transparent

1. to bend ==>  refract

2. not allowing light to pass through   ==>  opaque

3. only partially clear ==> translucent  

4. clear  ==>  transparent

Explanation:

1. to bend ==>  refract

When a substance (like water) or a surface (like a mirror) changes the direction of the light, it refracts it.

2. not allowing light to pass through   ==>  opaque

Usually a solid but also a thick/dark liquid can be an opaque barrier preventing the passage of light.

3. only partially clear ==> translucent  

Think about a white plastic or a film-coated glass pane, they will let you see there's light on the other side, but not letting it pass through completely.

4. clear  ==>  transparent

Think like a window or a anything similar that allows the light to pass through without any significant obstruction.

atomic mass = 39

number of neutrons = 20

number of protons= 19

electronic configuration = 1s2 2s2 2p6 3s2 3p6 4s1

the number of electron in first shell = 2

number of electrons in n=3 shell = 8