Matters- As pure and impure

 

Anything that occupies some space, having mass, volume and can be felt by one or more out of five senses is called matter. The purest form of matter is called an element. An element is a substance which cannot be split up into two or more simpler substances by the usual chemical methods of applying heat, light or electric energy.

A pure substance consists of a single type of particles. All the elements and compounds are pure substances because they contain only one kind of particles. eg. Hydrogen, Carbon, Oxygen, Carbon-monoxide,Copper, Gold, Silver.

 

A pure substance has a fixed composition as well as a fixed boiling point and melting point. The presence of impurities generally increases the melting and boiling point of the pure substances

 

Q: 8.1 Which of the statement is true about pure substances

a.     Homogeneous mixtures are pure as they have same composition throughout.

b.     22 carat goldis pure in nature.

c.     Elements are not pure in nature.

d.     Gold and carbon dioxide both are pure in nature.

 

Q: 8.2 The boiling point of pure water is 100^oC. What likely be the effect on the boiling point of water if 150 gm NaCl is added to one litre of water ?

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Q: 8.3 Carbonmonoxide gas can be separated into carbon and oxygen gas by ________________.

     a.     Chemical methods

     b.     Applying heat,

     c.     Sunlight or electric energy

     d.     None of the above.

Q: 8.4The melting point of 1 Kg carbon dioxide is –79°C. What will be the melting point of 500gmCarbondioxide?

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Q: 8.5 Why table salt resist free flow and becomes damp during rainy season moisture if exposed to damp air although sodium chloride does not hygroscopic?

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Q: 8.6 Universe is made up of matter justify this statement?

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Answer Key and Credit:

ANSWER 8.1:-

 

Scientific Literacy:

FRAMEWORK	CHARACTERISTICS
Competency	Evaluate and design scientific enquiryExplain the phenomenon scientifically
Knowledge system	Knowledge of science-Physical
Context	Global
Cognitive demand	Low
Item format	Simple Multiple choice question.
Proficiency level	2

 

Credit Pattern:

Full Credit:	2
Partial Credit:	1
Nil Credit:	0

 

Full Credit:	(D)(d) Gold and carbon dioxide both are pure in nature.
Partial Credit:	Only if one factor is mentioned like Gold or Carbonmondioxide
Nil Credit:	Other responses.(A), (B) and (C)

 

ANSWER 8.2:-

Scientific Literacy:

FRAMEWORK	CHARACTERISTICS
Competency	Interpret data and evidencescientificallyEvaluate and design scientific enquiry
Knowledge system	Knowledge of science-Physical
Context	Global
Cognitive demand	Medium
Item format	Closed constructive
Proficiency level	4

Credit Pattern:

Full Credit:	2
Partial Credit:	1
Nil Credit:	0

 

Full Credit:	Boiling point of water will increase.
Partial Credit:	101oC or above
Nil Credit:	Boiling point of water will remains constant or decreasies.

 

ANSWER 8.3:-

Scientific Literacy:

FRAMEWORK	CHARACTERISTICS
Competency	Use scientific evidences to draw conclusion
Knowledge system	Procedural
Context	Global
Cognitive demand	Low
Item format	Simple Multiple choice question.
Proficiency level	2

Credit Pattern:

Full Credit:	2
Partial Credit:	1
Nil Credit:	0

 

 

Full Credit:	(D) None of the above.
Partial Credit:	------
Nil Credit:	Other responses.(A), (B) and (C)

 

ANSWER 8.4:-

Scientific Literacy:

FRAMEWORK	CHARACTERISTICS7
Competency	Interpret Data and Evidence Scientifically
Knowledge system	Physical
Context	Global
Cognitive demand	Low
Item format	Closed constructive
Proficiency level	1

Credit Pattern:

Full Credit:	2
Partial Credit:	1
Nil Credit:	0

 

 

Full Credit:	Same –79°C.
Partial Credit:	------
Nil Credit:	Other responses or missing

 

ANSWER 8.5:-

Scientific Literacy:

FRAMEWORK	CHARACTERISTICS7
Competency	Evaluate and design scientific enquiry
Knowledge system	Earth
Context	Global
Cognitive demand	High
Item format	Closed constructive
Proficiency level	5

Credit Pattern:

Full Credit:	2
Partial Credit:	1
Nil Credit:	0

 

Full Credit:	The presence of CaCl2 and MgCl2 impurities in table salt absorb moisture if exposed to moist air and resist free flow.
Partial Credit:	Due to the presence of impurities.
Nil Credit:	Any other or missing.

ANSWER 8.6:-

Scientific Literacy:

FRAMEWORK	CHARACTERISTICS7
Competency	Evaluate and design scientific enquiry
Knowledge system	Earth
Context	Global
Cognitive demand	High
Item format	Closed constructive
Proficiency level	5

Credit Pattern:

Full Credit:	2
Partial Credit:	1
Nil Credit:	0

 

Full Credit:	Space research have shown that all the star, planet and satellites are very big in size and made up of solid particle and sometimes possess (gaseous) atmosphere. Even our earth planet contains soil, mineral rocks, water and atmosphere therefore according to the definition mentioned anything that occupies some space, having mass, volume and can be felt by one or more out of five senses is called matter.
Partial Credit:	Universe is made up of solid liquid and gases.
Nil Credit:	Any other or missing.