GENERAL SCIENCE

• Matter is defined as anything that occupies space and possesses the attributes of gravity and inertia.
• Solid is characterized by resistance to any change in shape, caused by a strong attraction between the molecules of which it is composed.
• Liquid doesn't resist forces that act to change its shape, because the molecules are free to move with respect to each other.
• Gas is a state of matter in which molecules are widely dispersed and freely move.
• Plasma is the fourth state of matter consisting of an overall charge-neutral mix of electrons, ions, and neutral atoms.
• The melting point or freezing point is the temperature at which any given substance changes from solid to liquid and vice versa.
• The boiling point is the temperature at which it changes from liquid to gas and vice versa.
• A physical change is a change in matter that involves no chemical reaction.
• When a substance undergoes physical change, the composition of its molecules remains unchanged, and the substance doesn't lose its chemical identity.
• Melting, evaporating, and freezing are three types of physical change.
• Cutting, grinding, crushing, annealing, dissolving, or emulsifying produce physical changes.
• Still another physical change is sublimation, the change from a solid to a gas.
• When a substance undergoes a chemical change, the chemical composition of each molecule changes.
• Machines are devices that can do any of the following: (a) multiply force; (b) multiply speed or distance; (C) change the direction of the force; (d) transfer energy from one place to another; and (e) transform energy from one form to another.
• Those that only have one or two parts each are called simple machines, while those that make use of two or more simple machines are called compound/complex machines.
• Scientists have classified simple machines into six groups, namely: inclined plane, lever, screw, wheel and axel, pulley, and wedge.
• The density of a substance is equal to the mass of the material divided by its volume. A solid has a higher density than a liquid or gas because its particles are very close to one another.
• Climate is the long-term effect of the sun's radiation on the rotating earth's varied surface and atmosphere.
• Weather is a state of the atmosphere at a particular time and place.
• Temperature is a measure of the degree of hotness of the air.
• Three different scales are used for measuring temperature. Scientists use the Kelvin (absolute) scale, Celsius (centigrade) scale and the Fahrenheit scale.
• The thermometer is the common instrument used to measure temperature.
• Humidity is a measure of the amount of water vapor in the air.
• Both hygrometer and psychrometer are instruments used in measuring atmospheric humidity.
• Barometer is an instrument that measures changes in atmospheric pressure.
• Wind is the movement of air from one place to another.
• Atmospheric pressure refers to the weight of the air above us.
• Anemometers are devices used to measure wind speed.
• A barograph records changes in atmospheric pressure over time.
• Wind vanes indicate direction of wind movement.
• Precipitation is produced when the droplets and crystals in clouds grow large enough to fall to the ground.
• Precipitation is measured using an instrument called rain gauge.
• Clouds are excess water vapor in the air that condenses into liquid droplets or ice crystals.
• Fluffy cumulus clouds form from rising masses of air, called thermals.
• If a cumulus cloud grows large, it transforms into a cumulonimbus cloud or thunderstorm.
• Fibrous cirrus clouds consist of trails of falling ice crystals twisted by the winds.
• Stratus clouds form when an entire layer of air cools or ascends obliquely.
• Water is odorless, tasteless, and colorless.
• Water is a universal solvent, meaning it can dissolve a wide variety of substances.
• Water has a freezing point of 0 degrees Celsius and a boiling point of 100 degrees Celsius.