In the determination of boiling point of water, it is advised to put the bulb of the thermometer in the steam rather than in water, it is to :
reduce the error due to atmospheric pressure.
make sure that boiling point obtained is accurate even when water sample contains non - volatile impurities dissolved.
reduce the error due to expansion of glass because of heat.
obtain the boiling point in a shorter time.
While determining the boiling point of water, we should always use distilled water because :
impurities may break the thermometer.
impurities increase the boiling point of water.
impurities decrease the boiling point of water
impurities may stick to the thermometer making it difficult to read the temperature.
While determining the melting point of ice, Karan used a glass stirrer. The purpose of using glass stirrer is to :
help the fusion process
keep the temperature uniform
increase the kinetic energy
decrease the kinetic energy
The force of attraction between the particles is greater in
Oxygen
Liquid state
Solid state
Gaseous state
At room temperature (30°C) a student sets up an apparatus to determine the melting point of ice. He takes a beaker filled with ice and dips a mercury thermometer in it.The correct observation is:
mercury in the thermometer keeps on falling till reads 1°C, it remains constant thereafter.
temperature falls, reaches 0°C, then it reamins constant even after the whole ice has melted.
the temperature falls initially but begins to rise as soon as the ice starts melting.
temperature falls, reaches to 0°C and remains constant only as long as both ice and water are present in it.
The sun and the stars glow because of the presence of
Hydrogen
Helium
Plasma
Atmosphere
It can flow and change shape
Liquids
Solids
Gases
Stones
The amount of water vapour present in air is called
Density
Fluidity
Viscosity
Humidity
A substance having a definite shape and definite volume is called
Solid
plasma
liquid
gas
The aquatic animals can breathe under water due to the presence of dissolved
Carbon dioxide
Nitrogen
