Physical states matter|chapter 5 9th|tutoronlines

chapter # 5


Table of content:

Sr. No Name of Topics
1 Vapour pressure
2 Boiling point
3 Transition temperature
4 Systolic pressure
5 Melting point
6 Amorphous solids and Crystalline solids
7 Allotropy
8 Physical properties
9 Evaporation

Give the Answer of the following Question

Q.No.26. Write down two factors on which vapour pressure depends upon?

Ans. The vapour pressure of liquid depends upon following factors.

Molecular size:

The small size molecules vaporize rapidly as compared to big ones.


As compare to low temperature, at high temperature vapour pressure is high.

Q.No.27. Define the term vapour pressure?

Ans. The pressure exerted by the vapours of a liquid at equilibrium with the liquid at particular temperature is called vapour pressure.

Q.No.28. Convert 70cm Hg to atm?

Ans. By converting 70cmHg to atm
76cm Hg = 1 atm
1cm Hg = 1/76 atm
70 cm Hg = 70/76 atm= 0.92 atm

Q.No.29. Define boiling point? What is boiling point of alcohol?

Ans. The temperature at which vapour pressure of liquid become equal to external pressure. Boiling point of alcohol is 78 centigrate.

Q.No.30. Why meat is preserved curing with salt?

Ans. Table salt is the most important ingredient for curing meat and is used in large quantity. Salt kills and inhibit the growth of putrefying bacteria by drawing water out of meat. Concentration of salt up to 20% is required to kill most species of unwanted bacteria. Once properly salted, the meat contains enough salt to prevent the growth of many undesirable microbes.

Q.No.31. What is relationship between external pressure and boiling point?

Ans. The boiling point of liquid is directly proportional to external pressure. With the increase of external pressure boiling point also increased.

Q.No.32. Name the factors which affect the vapour pressure of liquid?

Ans. Following are the factors that affect the vapour pressure of liquid.
(i) Nature of liquid
(ii) Molecular size
(iii) Temperature

Q.No.33. Convert the 3.5 atm or torr?

Ans. 3.5 atm to torr
1 atm = 760 torr
3.5 atm=3.5×760=2660torr

Q.No.34. Define transition temperature and give an example?

Ans. A temperature at which one allotrope is converted to another is known as transition temperature. For example transition temperature of sulphur is 96 degree centigrate. Below this temperature it is found in rhombic form. If rhombic form again heated till 96 degree, it is change into monoclinic from.

Q.No.35. Convert 700 mm of Hg into atmosphere (atm)?

Ans. 760 mm Hg = 1atm
1mm Hg =1/760
700mm=700/760 mm Hg = 0.92 atm

Q.No.36. Define systolic pressure?

Ans. When heart is pumping, the value of blood pressure that represent this values of pressure is know as systolic pressure e.g 120

Q.No.37. Define the term melting point?

Ans. The temperature at which solid starts melting and coexist in dynamic equilibrium with liquide state is called melting point.

Q.No.38. Differentiate between boiling point and melting point?
Ans. Melting point:

A temperature at which solid starts melting and coexist with liquid state at dynamic equilibrium.

Boiling point:

A temperature of liquid becomes equal to atmospheric pressure.

Q.No.39. What is the effect of temperature on density of gases?

Ans. By lowering the temperature the volume of gases decreases, while density increased. In normal atmospheric pressure the density of oxygen at 20 degree centigrade is 1.4 gd/m3 and at 0 degree centigrade it is 1.5 gd/m3.

Q.No.40. Differentiate between amorphous solids and crystalline solids?
Ans. Amorphous solids:

Amorphous means shapeless. Solids in which the particles are not regularly arranged or those having not regular shapes are called amorphous solids. For example, Rubber, Plastic.

Crystalline Solids:

Solids in which particles are arranged in definite three dimensional pattern are called crystalline solids. For example, Salt and diamond.

Q.No.41. What is meant by Amorphous Solid?

Ans. Amorphous means shapeless. The type of solids in which particles are not properly arranged or those having not proper shapes are called amorphous solids. For example, Plastic, Rubber.

Q.No.42. Define crystalline solid and give its two example?

Ans. Those solids whose particles are organized three dimensionally called crystalline solids. They have high melting and boiling point. For example, Diamond, Salt.

Q.No.43. Define Allotropy?

Ans. The existence of an element in two or more from in same physical state is known as allotropy.

Q.No.44. Write two reasons of allotropy?

Ans. Two reasons of allotropy are following:
(1) Occurrence of element in two or more forms, having different number of atoms i.e allotropy of oxygen O2 and O3.
(2) Different arrangement of molecules or atoms in crystal of element like sulphur crystal show allotropy due to different arrangement of molecules.

Q.No.45. Why solids show rigidity?

Ans. Due to strong intermolecular force the molecules of solid do not move, they are tightly packed. That is why solids have specific shape.

Q.No.46. What are the physical properties of matter?

Ans. The simplest form of matter is gas.
1. In gaseous state, matter has no specific shape and volume.
2. Gas molecules are mobile, they can easily pressed.
3. In liquid form, matter has specific volume, but not shape.
4. By hearting, their volume is increased.
5. In solid form matter has specific shape and volume.
6. On heating solids melts and change into liquid or gaseous state.

Q.No.47. Define diffusion, explain with an example?

Ans. Spontaneous mixing up of gas molecules by random motion and collusion to make homogeneous mixture, called diffusion.
Diffusion depends upon the molecular mass of gases, light gases diffuse rapidly e.g hydrogen (H2) gas diffuses four times rapidly than oxygen (O2) gas.

Q.No.48. Why does evaporation increase with increase of temperature?

Ans. At high temperature, rate of evaporation becomes fast, because at high temperature, the kinetic energy of molecules become very high and over come the intermolecular forces. For example water level in hot water container decreases earlier than than that of cold water. This is because the hot water evaporate earlier.

Q.No.49. Why are the liquids mobile?

Ans. Among the molecules of liquid intermolecular forces are not much strong, to keep them stationary, instead the molecules keeps on moving freely under the surface of liquid. That’s why liquid have not definite shape but have definite volume.

Q.No.50. Why is the boiling point of water higher than that of alcohol?

Ans. The intermolecular forces in water are much strong than that of alcohol, that is the reason why water has high boiling point.

Q.No.51. Why evaporation causes cooling?

Ans. Evaporation is a cooling process when the high kinetic energy molecules vaporise the temperature of remaining molecule fall down. To compensate this deficiency of energy, molecules of liquid absorb energy from surrounding . As a result temperature of surrounding decreases and we cool effect.

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