Material property: the density of low-density polyethylene (LDPE) is approximately how many grams per cubic centimetre at room temperature?

Introduction / Context:
Polyethylene density correlates with branching and crystallinity: LDPE is more highly branched and therefore less crystalline—and less dense—than HDPE. Memorising representative densities helps in quick identification of polymer type and predicting stiffness and barrier properties.

Given Data / Assumptions:

• LDPE typically ranges from about 0.91 to 0.93 g/cm³.
• Density values are at 23–25 °C for solid material.

Concept / Approach:
Among provided options, 0.91 g/cm³ aligns with standard LDPE values. Numbers such as 0.38 or 0.56 g/cm³ are far below organic solids (closer to foams); 0.81 g/cm³ is too low for non-foamed PE; 1.01 g/cm³ exceeds typical PE densities and approaches aqueous media or filled systems. Therefore, 0.91 g/cm³ is the appropriate selection for compact LDPE.

Step-by-Step Solution:

Verification / Alternative check:
Materials datasheets for LDPE grades consistently list densities around 0.920 ± 0.010 g/cm³ depending on comonomer and branching.

Why Other Options Are Wrong:

• 0.38, 0.56: not realistic for solid, unfoamed polyethylene.
• 0.81: too low for solid LDPE; would imply high voids/foam.
• 1.01: above typical polyethylene density; more like PET blends or filled systems.

Common Pitfalls:
Mixing up LDPE and HDPE densities; HDPE is typically 0.94–0.97 g/cm³.

Final Answer:
0.91