science chapter 1 and 2

• a corrosive chemical is a chemical that can cause severe damage on the skin when come into contact.
• a harmful or irritant chemical are chemicals that can lead to irritation/ allergic reactions or inflammatory of the skin. may cause drowsiness and dizziness has many harmful health effects and may cause haem to the ozone layer
• environmental toxicity is a chemical that may cause harmful effects to the environment.
• a oxidising substance releases oxygen easily that causes fires and explosions.
• gases under pressure may explode when heated and may cause oxygen deficiency when leaked in an enclosed environment.
• acute toxicity can cause toxic or harmful effects to the body when breathed in, swallowed or on contact with the skin. may be fatal.
• explosives are chemicals that may cause explosions and fires when come into contact with heat
• flammable : highly flammable, may cause fires or explosions when reacted with air,water or any other chemicals.
• aspiration hazard : can cause breathing difficulties and damage to the organs and lead to lung cancer.
• why does the density of an object not change when cut into may pieces?

  since density =mass divided by volume, when the object is cut, the mass and volume are changed by the same proportion, so the density would remain the same
• is density a useful property for identifying a unknown substance?

  yes, as density is unique to each substance, density acts as an reference to help us find the identity of the unknown substance.
• density= mass/volume
• changed variable= independent variable
• dependent variable = measured variable
• hypothesis= an explanation of the experiment before being conducted.