5 The unit for measurement for density is......

Reactants are the substances on the left side of the arrow in a chemical equation, which are consumed during the reaction. Products are on the right side.
In the given reaction: Carbon + oxygen $\rightarrow$ carbon dioxide
The substances on the left are Carbon and oxygen.

The reactants are Carbon and oxygen.

The correct option is C. Carbon and oxygen.

Heating a substance provides energy to its constituent particles (atoms or molecules). This energy is primarily converted into kinetic energy.

• A. Gain kinetic energy: When particles gain kinetic energy, they move faster and vibrate more vigorously. This is consistent with heating.
• B. Move slower: This is incorrect; heating makes particles move faster.
• C. Remain the same: This is incorrect; heating changes the energy and motion of particles.
• D. Come closer to each other: This is generally incorrect; increased kinetic energy usually leads to particles moving further apart, causing expansion.

The correct option is A. Gain kinetic energy.

Density ($\rho$) is defined as mass per unit volume.

Common units for mass include grams (g) and kilograms (kg).
Common units for volume include cubic centimeters (cm³), cubic meters (m³), and cubic decimeters (dm³).

Possible units for density include g/cm³, kg/m³, kg/cm³, or g/dm³.

• A. Km/m²: This is a unit of length per area, not density.
• B. Kg/cm³: This is a unit of mass (kg) per volume (cm³), which is a valid unit for density.
• C. g/dm: This is a unit of mass (g) per length (dm), not density. For density, it would be g/dm³.
• D. °C: This is a unit for temperature, not density.

The correct option is B. Kg/cm³.