What allows composites (such as carbon-fiber-reinforced polymers) to be so strong and elastic? select all that apply.
- high kinetic energy of the molecules
- extensive cross-linking between molecules
- size of polymer molecule
- properties of metals and plastics

I think there would be two correct answers from the choices listed above. These are the second and the last option. Composites are strong and elastic because of the extensive cross-linking between molecules and the properties of metals and plastics. Hope this answers the question.

Grams of Chromium(III) nitrate produced : 268.95 g

Further explanation

Given

0.85 moles of Lead(IV) nitrate

Required

grams of Chromium(III) nitrate

Solution

Reaction

Balanced equation :

2Cr₂ + 3Pb(NO₃)₄ ⇒ 4Cr(NO₃)₃ + 3Pb

From the equation, mol ratio of Pb(NO₃)₄  : Cr(NO₃)₃ = 3 : 4, so mol Cr(NO₃)₃

mol Cr(NO₃)₃ =

Mass of Chromium(III) nitrate (MW=238.0108 g/mol) :

mass = mol x MW

mass = 1.13 x 238.0108

mass = 268.95 g