3. triangle abc has angle measures as shown.

x = 21 and ∠C = 136°

Step-by-step explanation:

(a)

The sum of the 3 angles in a triangle = 180°, hence

x + x + 2 + 6x + 10 = 180

8x + 12 = 180 ( subtract 12 from both sides )

8x = 168 ( divide both sides by 8 )

x = 21

(b)

∠C = 6x + 10 = (6 × 21) + 10 = 126 + 10 = 136°

the answer is: d) o, f, and kr.

atomic radius of bromine (br) is 114 pm.

atomic radius of oxygen (o) is 73 pm.

atomic radius of fluorine (f) is 72 pm.

atomic radius of krypron (kr) is 112 pm.

the atomic radius of a chemical element is a measure of the size of its atom.

the atomic radius varies with increasing atomic number, but usually increases because of increasing of number of electrons.

the atomic radius decreases across the periods because an increasing number of protons, because greater attraction between the protons and electrons.