Combined Science Flashcards

What causes rust to form on iron?

Answer: Iron reacts with oxygen and water to form iron oxide (rust)

Rust (hydrated iron oxide) forms when iron reacts with both oxygen and water. The chemical formula is Fe₂O₃·xH₂O. Both oxygen and water are needed for rusting.

What is refraction?

Answer: The bending of light as it passes from one medium to another of different density

Refraction is the bending of light (or other waves) as it passes from one medium to another with a different refractive index (optical density), causing a change in speed and direction.

What is the term for the movement of particles from high concentration to low concentration?

Answer: Diffusion

Diffusion is the net movement of particles (molecules or ions) from an area of higher concentration to lower concentration — moving down the concentration gradient.

Which gas is produced when a metal reacts with an acid?

Answer: Hydrogen

When a metal reacts with an acid, hydrogen gas is produced along with a salt: Metal + Acid → Salt + Hydrogen. The hydrogen burns with a squeaky pop.

What is the role of kidneys in the body?

Answer: To filter blood and remove waste products (urea, excess water, salts) as urine

The kidneys filter blood to remove metabolic waste products (especially urea from protein breakdown), excess water, and excess salts, excreting them as urine.

What is Newton's Second Law of Motion?

Answer: Force = mass × acceleration (F = ma)

Newton's Second Law states F = ma: the net force on an object equals its mass multiplied by its acceleration. A larger force on the same mass produces greater acceleration.