#1
Which of the following is an example of a solid?
Ice
ExplanationSolid: Maintains shape and volume; molecules tightly packed.
#2
What is the boiling point of water in Celsius?
100°C
ExplanationWater boils at 100°C at standard atmospheric pressure.
#3
What is the unit of pressure?
Pascal
ExplanationPascal: SI unit of pressure; equal to one newton per square meter.
#4
What is the boiling point of nitrogen in Celsius?
-196°C
ExplanationNitrogen boils at -196°C at standard atmospheric pressure.
#5
What is the freezing point of mercury in Celsius?
-38.83°C
ExplanationMercury freezes at -38.83°C.
#6
Which of the following is NOT a property of gases?
Definite volume
ExplanationGases have no definite shape or volume; they expand to fill the container.
#7
What is the process called when a gas changes directly into a solid?
Deposition
ExplanationDeposition: Gas transforms directly to solid without passing through liquid phase.
#8
What is the process called when a liquid changes into a gas?
Evaporation
ExplanationEvaporation: Liquid to gas transformation at the surface, below boiling point.
#9
Which of the following is NOT a state of matter?
Energy
ExplanationEnergy is a property, not a state of matter.
#10
What happens to the volume of a gas when its pressure is increased?
Decreases
ExplanationAccording to Boyle's Law, when pressure increases, gas volume decreases.
#11
Which gas is known as laughing gas?
Nitrous oxide
ExplanationNitrous oxide: Chemical compound with the formula N2O; often used as an anesthetic.
#12
What is the critical point of a substance?
The temperature and pressure at which the gas and liquid phases of a substance become indistinguishable
ExplanationCritical point: Conditions beyond which distinct liquid and gas phases no longer exist.
#13
What is the process called when a gas changes into a liquid?
Condensation
ExplanationCondensation: Gas to liquid transformation, opposite of evaporation.
#14
What is the state of matter characterized by having no fixed shape or volume?
Gas
ExplanationGas: Molecules are widely spaced and move freely.
#15
What is the process called when a solid changes directly into a gas?
Sublimation
ExplanationSublimation: Solid transitions directly to gas phase.