2622 cal =  ___ kcal

385 cal =___ J

In which of the following states the potential energy is the highest?

How do we know that a substance has changed state from solid to liquid at a molecular level?

Match the following:

State	Attributes
a. Solid	i. Highest kinetic energy of the molecules
b. Liquid	ii. Highest potential energy of the molecules
c. Gas	iii. Moderate K E and P E

In which of the following physical states the intermolecular space is the highest?

Inter molecular is the force of attraction or repulsion which act between neighboring particles(atoms, ions, molecules). These forces are weak compared to the other , such as covalent or ionic bonds between atoms in a molecule. The order of force of inter molecular attraction: solids > liquids > gases

What kind of energy is associated with the motion and speed of the particles constituting a substance?

• Matter is composed of tiny particles (atoms, molecules or ions)
• These particles are in constant, random motion and possess kinetic energy.
• The particles also have potential energy due to inter- molecular attractions.
• The average kinetic energy increases as the temperature increases.
• If two particles of different masses are moving at the same speed, the heavier particle will have higher kinetic energy.
• Similarly, for particles of the same mass moving at the different speeds, the faster one will possess the greater kinetic energy.

Internal energy = _____ + _______.

The sum of the electronic energy, nuclear energy, chemical bond energy, potential energy and kinetic energy. Internal energy is made up of kinetic energy and potential energy of the constituent particles. The kinetic energy arises due to the motion of its particles like translational energy, rotational energy, vibrational energy etc. The potential energy arises from different types of interaction between the particles, and it includes electronic energy, nuclear energy,energy due to molecular interaction,etc.
The S.I.unit of internal energy is Joule(J).
The C.G.S unit of internal energy is ergs.

The particles of a substance possess _____.

The molecules of which form of water have the highest kinetic energy?

Out of the three states of matter,  gaseous phase has always maximum kinetic energy...so water molecules also possess the highest kinetic energy in gaseous phase that is in the steam form. We have to give energy to liquid water to make water vapour and this energy goes as kinetic energy of molecules.
And also we can observe that gas occupy all the volume available to it. This is also possible due to kinetic energy.

When an ice cube is dropped into a cup of hot coffee, the heat flows from _________.

Heat is the transfer of thermal energy between that are at different temperatures. Energy is always transferred from the warmer object(which has a higher temperature) to the cooler one(which has lower temperature). Similarly, molecules with a lot of energy move faster than molecules with smaller amount of energy, thus causing the former to have more heat.
For example, an ice cube in a glass of water eventually melts.This is because, the heat from the water, which is warmer, flows to ice cube until both are at the same temperature, and therefore no ice cube is left.

The force of attraction between the water molecules gives rise to _________________.

1 cal = ___ J

1 kcal = ____ cal.

1 Joule = ________________ Erg.

The S I unit of heat is _____________.