CBSE Class 11 Chemistry States of Matter Worksheet Set A

Short Answer

Question. What do you mean by the thermal energy? 
Answer. Thermal energy is the energy of a body arising from the motion of its atoms or molecules. The atoms or molecules of a hotter object have greater kinetic energy than those of a colder one, in the form of vibrational, rotational, or, in the case of a gas, translational motion.

Question. What do you mean by the term dipole-induced dipole forces? 
Answer. A dipole-induced dipole attraction is a weak attraction that results when a polar molecule induces a dipole in an atom or in a nonpolar molecule by disturbing the arrangement of electrons in the nonpolar species, for example: hydrogen chloride (HCl): the positive end of a polar molecule will attract the negative end of the other molecule and influence its position. Polar molecules have a net attraction between them.

Question. Define thermal interaction? 
Answer. Thermal interaction, or heat energy transfer, to take place, two bodies must be in contact whether this be the particles of air in contact with your skin to make you feel warm or cold, or the thermal interaction that takes place when an ice cube is dropped into a bowl of warm water.

Question. What is absolute zero?
Answer. Absolute zero is the lowest possible temperature where nothing could be colder and no heat energy remains in a substance. International agreement, absolute zero is defined as precisely; 0 K on the Kelvin scale, which is a thermodynamic (absolute) temperature scale; and –273.15 degrees celsius on the celsius scale.

Question. What do you mean by the Gay Lussac’s Law?
Answer. Gay Lussac’s Law states that at constant volume, pressure of a fixed amount of a gas varies directly with the temperature.
Mathematically p ∝ T
= P / T = constant = k3
Pressure and temperature at constant volume are directly proportional.

Long Answer

Question. Explain the Avogadro Law? 
Answer. 
Avogadro's law states that investigates the relationship between the amount of gas (n) and volume (v). In the industrial synthesis of methanol, knowing the temperature and pressure makes it easier for experts to calculate molar amounts that permit good estimation of stoichiometric relationships in the system. Avogadro's laws mathematical formula as: V ∝ n or V/n = k. Where V is the volume of the gas, “n” is the amount of the gas (number of moles of the gas) and k is a constant for a given pressure and temperature. The number of the molecules in one mole of a gas has been determined to be 6.022 * 1023 and is known as the Avogadro constant. The law is approximately valid for real gases at sufficiently low pressures and high temperatures. The important features for the Avogadro’s law are:
1. The molar volume of all ideal gases at 0°C and 1 atom pressure is 22.4 liter.
2. If pressure and temperature of a gas are constant, when the amount of gas increases, the volume increases.
3. If pressure and temperature of a gas are constant, when the amount of gas decreases, the volume decreases.
For example: the molecular weight of oxygen is 32.00, so that one gram-mole of oxygen has a mass of 32.00 grams and contains 6.02214076 × 1023 molecules.

Question. Difference between London forces and dipole-dipole forces? 
Answer. 1. London forces are attractive forces between all kinds of molecules including polar, non-polar, ions, and noble gasses whereas dipole-dipole forces are attractive forces between molecules with permanent dipole movements.
2. London forces have higher bond strength whereas dipole-dipole forces have weaker bond strength.
3. London forces occur when a positively charged nucleus of an atom attracts the electron cloud of another atom whereas dipole-dipole forces occur when there is an unequal sharing of electrons between two atoms.
4. London forces instantaneous dipoles must exist whereas dipole-dipole forces have weaker bond strength.
5. London forces are the attraction between two non-polar molecules whereas dipole-dipole forces are the attraction between two polar molecules.

Question. Explain about Charles’ Law? 
Answer. 
Charles law states that the volume of a given amount of gas held at constant pressure is directly proportional to the Kelvin temperature. As the volume goes up, the temperature also goes up, and vice-versa. The volume of a fixed mass of a gas decreases on cooling it and increases by increasing the temperature. For one degree rise in temperature, the volume of the gas increases by its original volume at 0˚C. The temperature in Kelvin can be calculated via Tk = TC + 273.15. A plot of the temperature in Kelvin. Charles' law predicts that volume will be zero at 0 K. 0 K is the absolutely lowest temperature possible, and is called absolute zero. Charles' Law gives the relationship between volume and temperature if pressure and amount of gas are held constant. If the volume of a container is increased, the temperature increases. If the amount of gas in a container is increased, the volume increases.
Mathematically, the direct relationship of Charles's Law can be represented by the following equation:
VT=k
V / T = constant = k₂.

Question. Explain the Boyle’s Law? 
Answer. Boyle's law also known as Mariotte's law and the Boyle-Mariotte law, it is a law about ideal gases. The volume of a constant mass of ideal gas at a constant temperature is inversely proportional to the pressure applied on it. This empirical relation, formulated by the physicist Robert Boyle in 1662. Boyle's Law states that the pressure (P) of a gas is inversely proportional to the volume (V). This law is valid as long as the temperature and the amount of gas are constant. Any units will work here: PV=k (constant). The constant k will depend on the number of moles and the temperature.
For example: When the plunger on a sealed syringe is pushed, the pressure increases and the volume decreases. The pressure decreases dramatically as they are raised, increasing the volume of gases in their blood and swim bladder. Boyle's law is important because it tells us about the behaviour of gasses. It explains, with certainty, that the pressure and volume of gas are inversely proportional to one another. So, if we push on gas, its volume becomes smaller and the pressure becomes higher. Boyle's Law is used to predict the result of introducing a change in volume and pressure only, and only to the initial state of a fixed quantity of gas.

Question. Explain the gaseous state and its physical properties?
Answer. Gas is one of the four fundamental states of matter the others being solid, liquid, and plasma. A pure gas may be made up of individual atoms, elemental molecules made from one type of atom or compound molecules made from a variety of atoms. Gas is a state of matter that has no fixed shape and no fixed volume. Gases have lower density than other states of matter, such as solids and liquids. There is a great deal of empty space between particles, which have a lot of kinetic energy. There is a great deal of empty space between particles, which have a lot of kinetic energy. The particles move very fast and collide into one another, causing them to diffuse, or spread out, until they are evenly distributed throughout the volume of the container. The gaseous state is characterized by the following physical properties:
1. Gases are highly compressible.
2. Gases exert pressure equally in all the directions.
3. Gasses have much lower density than the solids and liquids.
4. Gasses mix evenly and completely in all proportions without any mechanical aid.
5. The volume and the shape of the gasses are not fixed.
6. In gasses particles are very loosely packed.
7. Gasses are highly compressible.