Dear students, prepare for chemistry class 9th chapter 5 long questions. These important long questions are carefully added to get you best preparation for your 9th class chemistry ch. 5 exams.
Our database contains a total of 0 questions for chemistry Short Questions. You’ll prepare using this huge databank.
Q no: 5(A) Define the Boyle's law. Explain the experiential verification of Boyle' law.
In 1662 Robert Boyle studied the relationship between the
volumnand pressure of a gas at constant temperature. Defination:
The volume of a given mass of a gas is
inverslyproportional to its pressure provided the temperature remains constant.
Its mathematical form is v= k/p
The relationship between
volumnand pressure can be verified by the following series of experiment.
Let us take some mass of a gas in a cylinder having a movable
pistenand observe the effect of increase of pressure on it volumn. when the pressure of 2 atmosphere is applied, the volume of the gas reduces as 1dm³. When pressure is increased to 4 atm, the volume of the gas reducesto 0.5 dm³,. When we calculate the product of volume and pressure for this experiment, the product of all these experiment is constant.
P1 V1=2atm x 1dm³ =2atmdm³
P2 V2 = 4atm x 0.5dm³ = 2atmdm³
P3 V3 = 6atm x 0.33dm³ = 2atmdm³
P4 V4 = 8atm x 0.25dm³=2atmdm³
Factors which affect diffusion in liquids,
Factors which affect diffusion in liquids are
1- Intermolecular forces:
Liquid having weak intermolecularforces
diffuses faster than those having strong intermolecularforces
2- Size of molecule:
Big size molecule
diffuse slowly forexample honey diffuses slowly in water
3- Shapes of molecule:
Regular shape molecule diffuses faster than irregular shaped molecules because they can easily slip over And move faster
Diffusion increases by increasing temperature because a high temperature the forces becomes weak.
Q no: 6(a) Define Charles Law. Give its experimental verification.<div><br></div>
J.Charles in 1787 presented his law. He studied the relationship between volume And termpuratureof a gas at consantpressure. Defination: Exprerimetal verification:
The volume of a given mass of a gas is directly proportional to the absolute temperature of the pressure is kept constant.
Its mathematical from
is V= kT
Let us take a certain amount of gas enclosed in a cylinder having a movable
poston. If the initial volume of gas V1 is 50cm³ and initial temperatureT1 is 25° C, on heating the cylinder upto100°c, its new volume V is about 62.5cm³ The increase in temperatureincrease the volume
Q no: 6(B) Discuss the factors which affect the <gwmw class="ginger-module-highlighter-mistake-type-1" id="gwmw-15858938264802209845783">vapour</gwmw>pressure.
The factors that
effect the vapourpressure are
1- Nature of Liquid:
Polar liquids have low
vapourpressure then non-polar liquids at the same temperature. This is because of strong intermolecular forces between the polar molecules of liquid.
2- Size of molecule:
Small sized molecule can easily evaporate than big sized
molecules hence, small sized molecular liquid exert more vapourepressure.
At high temperature,
vapourpressure is higher than at low temperature . At elevated temperature, the kinetic energy of the molecules increases enough to enable them to vaporize and exert pressure.
Q no: 7<gwmw class="ginger-module-highlighter-mistake-type-6" id="gwmw-15858943322353026469368">(</gwmw>A) Define boiling point. How is affected by intermolecular<gwmw class="ginger-module-highlighter-mistake-type-6" id="gwmw-15858943473768863150288">forces</gwmw>.
The temperature at which the
vapourpressure of a liquid becomes equal to the atmospheric pressure or any external pressure
When a liquid is heated, its molecules gain energy. The number of molecules which have more than average kinetic energy increase. More and more molecules become
energic enoyghto overcome the intermoleculeforces
Affected by intermolecular forces:
Q no<gwmw class="ginger-module-highlighter-mistake-type-6" id="gwmw-15858973181711211101590">(</gwmw>b) Explain types of solids and different between Amorphous solids and Crystalline Solids.
According to their general appearance solids can be classified into two types.
1- Amorphous solid:
Amorphous means shapeless. Solids in which the particle
are not regularly arrrangedor their regular shapes are destroyed. The do not have sharp melting point.
2- Crystalline Solid:
Solid in which particles are arranged in a definite three dimensional pattern. They have definite.
surfaces or faces. Each face has definite angle with the other. They have sharp melting points.
Explain gaseous state of matter give some typical properties
Matter exist in three forms
What is Boyle's law and give its experimental verifications?
Introduction: in 1662 Robert Boyle studied the relationship between the volume and pressure of gas at constant temperature.
Statement: he observed that " volume of a given masses of a gas is inversely proportional to its pressure provided the temperature remains constants".
Mathematical expression: mathematically it can be written as :
Where 'k' is proportionality constant. The value of k is same for the same amount of a given gas.
Therefore, Boyle's law can be stated as the product o pressure and volume of a fixed mass of a gas is constant at a constant temperature.
If P1V1=K then P2V2=k
where P1= initial pressure
P2= final pressure
V1= initial volume
V2= final volume
as above both equation have same constant therefore, their variables are also equal to each other.
this equation establishes the relationship between pressure and volume of the gas.
Define Charles's law and give its experimental verification
Introduction: the relationship between volume and temperature keeping the pressure constant was also studied. French scientist J.Charles in 1787 presented his law.
What is absolute temperature scale?
Introduction: Lord kelvin introduced absolute temperature scale or Kelvin scale. This scale of temperature stats from K or -273. 15C, which is given the name of absolute zero.
Absolute zero: It is the temperature at which an ideal gas would have zero volume.
Describe physical states of matter and role of intermolecular forces.
Physical states of matter and role of intermolecular forces:
Explanation: as you know that matter exists in three physical states; gas , liquid and solid. In the gaseous state, the molecules are far apart for each other. Therefore, intermolecular forces are very weak in them. But in the liquid and solid states intermolecular forces play a very important role on their properties.
In liquid state molecules are much closer to each other as compared to gases. As a result liquid molecules develop stronger intermolecular forces, which affect their physical properties like diffusion , evaporation, vapors pressure and boiling point.
What is evaporation and factors effecting on it?
Definition: " the process of changing a liquid into a gas phase is called evaporation".
Explanation with example: evaporation is an endothermic process( heat is absorbed) .Such as when one mole of water is liquids sate is converted into vapors form, it requires 40.7 KJ of energy.
What is vapor pressure and explain factors effecting on it?
Definition: the pressure exerted by the vapors of a liquid at equilibrium whit the liquid at a particular temperature is called vapor pressure of a liquid.
Explain boiling point in detail.
Definition: " boiling point is defined as the temperature at which the vapor pressure of a liquid becomes equal to the atmospheric pressure or external pressure".
Give some typical properties of liquid state of matter
Typical properties of liquid:
Diffusion: the liquid molecules are always in a state of continuous motion. They move from higher concentration to lower concentration. They mix up with the molecules of other liquids, so that they form a homogeneous mixture.
Example: when a few drops of ink are added in a beaker of water , ink molecules move around and after a while spread in whole of beaker . Thus diffusion has taken place . Liquids diffuse like gases but the rate of diffusion of liquids is very low.
Discuss the typical properties of solids
Definition: the temperature at which the solid starts melting and coexists in dynamic equilibrium with liquid state is called melting point.
Explanation: the solid particles possess only vibrational kinetic energy. When solids are heated, their vibrational energies increase and particles vibrate at their mean position with a higher speed. If the heat is supplied continuously, a stage reaches at which the particles leave their fixed positions and then become mobile . At this temperature solid melts.
What are main types of solids?
According to their general appearance solids can be classified into two types: amorphous solids are crystalline solids.
What is allotropy? explain it with example
Definition: the existence of an element in more than one forms in same physical state is called allotropy.
In which units blood pressure is measured? define systolic and diastolic also explain hypertension.
Blood pressure is measured using a pressure gauge. It may be a mercury manometer or some other device. Blood pressure is reported by two values, such as 120/80 , which is a normal blood pressure. The first measurement shows the maximum pressure when the heart is pumping. It is called systolic pressure. When the heart is in resting position,, pressure decreases and it is the second value called diastolic. Both of these pressure are measured in torr units. Hypertension is because of high blood pressure due to tension and worries in daily life. The usual criterion for hypertension is a blood pressure greater than 140/90 hypertension raises the level of stress on the heart and n the blood vessels . This stress increases the susceptibility of heart attacks and strokes.