CLASS 9 PRACTICALSKILLS

1] To determine the melting point of ice a student immersed the thermometer in thecrushed ice in a beaker. He then heated the beaker on a low flame and observed that during melting of ice the temperature :
A.   Is decreasing
B. Fist decreases and then continuously increases
C.  Is increasing
D. Remains constant Ö

2] In the mixture of iron filings and sulphur powder
A. both sulphur powder and iron filings gets attracted towards magnet
B.only sulphur powder gets attracted towards magnet
C.Neither iron filling nor sulphur gets attracted towards magnet.
D.only iron filings gets attracted towards magnet Ö

3] When a mixture of sulphur powder and iron filings is heated.
A. iron filings starts melting
B.sulphur sublimates leaving iron filling behind
C.sulphur melts
D. Ferrous sulphide is formed. Ö

4] A student added milk, white of an egg, common salt and sand separately to water kept in four separate beakers. He stirred the mixtures well and filtered each of them. On filtering, he obtained solid residue on the filter paper in case of :
A.    Milk
B.  White of an egg
C. Common salt
D.  Sand Ö

5] A student sets up an apparatus for determining the boiling point of water. He records the temperature after regular intervals and finds that water when it begins to boil:
A. Continuously rises
B.First remains constant and then rises
C.Remains constant
D.First rises and then becomes constant Ö

MATTER IN OUR SURROUNDING  CLASS IX

• List the important characteristics of matter

• Difference among solid, liquid and gas.

• List any five physical properties of liquids

• Classify the matter in terms of physical state and composition

• Simple and clear-cut definitions along with the differences between the following terms:

• Evaporation
• Sublimation
• Condensation

• Difference between latent heat of fusion and latent heat of vaporization

• What do you mean by volatile liquid?

• Definitions of melting point, boiling point and freezing point

• Read clearly about the sublimation process

• Identify the matter from the given terms:

Chair, Air, Love, Smell, Hate, Almonds, Thought, Cold, Cold drinks, Smell of perfume

• The smell of hot sizzling food reaches you several meters away, but to smell the cold food you have to get close to it. Give the logical explanation for the same

• What is Diffusion, and why gases diffuse rapidly?

• The mass per unit volume of a substance is called density (density=mass/volume). Arrange the following in order of increasing density:

     Air, Exhaust from chimneys, Honey, Water, Chalk, Cotton, and Iron

• Explain the application of compressibility in gases with an example

• Define the term evaporation

• Mention the uses of LPG and CNG

• What is SI unit of temperature? Give mathematical relation also

• Convert the following temperatures to Celsius scale:

     (a) 333 K

     (b) 473 K

• What is absolute temperature

• Which state of matter is most easily compressible

• A diver is able to cut through water in a swimming pool. Identify which property of matter is working here?

• Arrange the following substances in increasing order of intermolecular force of attraction:

     Water, Sugar, Oxygen

• Give reasons to justify:

     (a) Water at room temperature is in liquid form

     (b) An iron almirah is in solid form

• Diffusion becomes faster at higher temperatures. Why?

• Boiling is considered as bulk phenomenon. Why?

• Why does the temperature of a substance remains constant during melting and boiling even when heat is being supplied to it continuously?

• What factors affect the rate of evaporation?

• In which case evaporation of water will be faster; near the sea or far away from the sea.

• What do you mean by solid ice? Why CO2 is kept under low pressure

class 9 chemistry revision
MATTER IN OUR SURROUNDINGS
List two processes from which it may be concluded that the particles of a gas move continuously.

Ans: Compressibility and Brownian movement

Q. At what temperature does solid ice and liquid water co-exist together?  

Ans: At 00C, the  phases of water co exist called triple point.

Q. What is common among the three states of matter?

Ans: They all contain molecules.

Q. . Which property of gas is used in supplying oxygen cylinders to hospitals? 

Ans: Compressibility

Q. a substance x was highly compressible and could easily be liquefied. it could also take the shape of the container. Predict  the nature of the substance

Ans: 

Q. can a liquid turn into vapor without heating?

Ans: yes, By the process of evaporation as vaporization of water occur  below the boiling point under atmospheric pressure.

Q. What do you mean by Latent heat of Fusion?

Ans:  the heat required to change 1 kg of a solid substance into liquid state at the melting point of the substance. For example, amount of heat required to melt ice at 0 ° C into water, at 0 ° C will be known as the Latent Heat of Fusion of ice.

Q. What is compressibility? How it is negligible in solids?

Ans: Compressibility is the ability of a substance  to be reduced to its  volume under pressure. Solids are incompressible as their particles are held together. So, we can tell that compressibility is negligible in solids. 

Q. Two cubes of ice are pressed hard between two palms. After releasing the pressure, the cubes join together. Why?

Ans: Pressure is directly proportional to temperature  when we apply pressure, temp. Increases then the ice in contact melts and  it turns into water.  when pressure is removed, the temperature decreases again and  melted ice again freezes .Hence cubes join together.

Q. Explain why ice has lower density than water?

Ans: The mass per unit volume of a substance is called density (density = mass/volume). As the volume of a substance increases, its density decreases.

When water changes into ice, space between particles increases. These spaces are larger as compared to the spaces present between the particles of water. Thus, the volume of ice is become greater than that of water. Hence, the density of ice became lower than that of water. As, a substance with lower density than water can float on water. Therefore, icefloats on water

class 8
cell stucture

CHEMICAL EFFECTS OF ELECTRIC CURRENT

I. Write answer for the following as directly :

1. What is LED ?

2. Name a gas which burns with a pop sound.

3. Which electrode is connected to the negative terminal of a cell ?

4. Name the ions which are positively charged.

5. Name a device which is used for the electrolysis of water ?

6. Identify the following as electrolytes and non electrolytes :

a) dil HNo3 b) Benzene c) Petrol d) Zinc Chloride solution e) a solution of Naoh g) Ether h) Alcohol i) Common salt solution

7. State three uses of electrolysis.

8. Draw a neat diagram of voltameter and label it

class 7 science
Nutrition in animals

1. Fill in the blanks:

(a) The main steps of nutrition in humans are __________, __________, __________, _________ and __________.
(b) The largest gland in the human body is __________.
(c) The stomach releases hydrochloric acid and ___________ juices which act on food.
(d) The inner wall of the small intestine has many finger-like outgrowths called _________.
(e) Amoeba digests its food in the ____________ .

Mark T if the statement is true and F if it is false:

(a) Digestion of starch starts in the stomach. (T/ F)
(b) The tongue helps in mixing food with saliva. (T/ F)
(c) The gall bladder temporarily stores bile. (T/ F)
(d) The ruminants bring back swallowed grass into their mouth and chew it for some time.

3. Tick (✓) mark the correct answer in each of the following:

(a) Fat is completely digested in the
       (i) stomach      (ii) mouth      (iii) small intestine     (iv) large intestine

(b) Water from the undigested food is absorbed mainly in the
       (i) stomach       (ii) foodpipe       (iii) small intestine      (iv) large intestine

4. Match the items of Column I with those given in Column II:

Column I Food Components	Column II Product(s) of digestion
Carbohydrates	Fatty Acids and Glycerol
Proteins	Sugar
Fats	Amino acids

7. Name the type of carbohydrate that can be digested by ruminants but not by humans. Give the reason also.

Answer

Cellulose is a type of carbohydrate that can be digested by ruminants and not by humans. 
Ruminants have a large sac-like structure called rumen between the oesophagus and the small intestine. The cellulose of the food is digested here by the action of certain bacteria which are not present in humans.

8. Why do we get instant energy from glucose?

Answer

Glucose is simple sugar which is formed when carbohydrate get broken. Also, the carbohydrate get digested into glucose. Since, glucose does not have to be digested and thus acts as an instant source of energy.
9. Which part of the digestive canal is involved in:

(i) absorption of food ________________.
(ii) chewing of food ________________.
(iii) killing of bacteria ________________.
(iv) complete digestion of food ________________.
(v) formation of faeces ________________. 

CLASS 9 REVISION
1. Neha's mother is a good cook.She uses natural colours to give colours to different foods.She uses turmeric for yellow colour, spinach for green colour and pomegranate for red colour.She avoids synthetic colours.Answer the following questions based on the above information

(a) Name the technique used to separate pigments from natural colours.
(b) Name the  principle of that technique.
(c) Explain the values that are displayed by Neha's mother

2, Define evaporation.Out of nylon and cotton cloth, which is more comfortable.Why?
   Is evaporation and boiling same? if not , Why?

3. Give one example where both chemical and physical change take place together?

4.A solution contains 30g of glucose, 20g of sugar in 500g of water. Calculate the mass percentage of glucose and sugar respectively?

5 A given substance X has definite volume, no fixed shape and can diffuse well. What is the physical state of substance X?

.MCQ'S

1.. The sequence of steps taken for separating a mixture of ammonium chloride , sand and common salt is :
: a) sublimation, adding water, filtration , evaporation
 b) evaporation , adding water , filtration, sublimation
c) filtration , evaporation , sublimation , adding water
d) adding water , evaporation , sublimation , filtration

 2. A student takes some water in a beaker and heats it over a flame for determining the boiling point. He keeps on taking its temperature readings. He would observe that the temperature of water

a) keeps on increasing regularly
 b) keeps on increasing irregularly
 c) first increases slowly , then decreases rapidly and eventually becomes constant
 d) first increases gradually and then becomes constant

 3. The layer deposited on iron nails dipped in copper sulphate solution is a) iron b) copper c) sulphur d) oxygen

4.The gas which evolves when zinc reacts with dil. Sulphuric acid
a) helps to light a glowing splinter into flame
 b) gives a pop sound with lighted match stick
c) extinguishes a lit candle brought near it d) none of the above

5. To prepare a colloidal solution of starch , we should
a) add starch in boiling water and cool
b) add starch to cold water and boil
c) heat starch powder , add cold water and then bring to boil
d) add a thin paste of starch in boiling water while stirring

 6. From which one of the following, its components can be separated by filtration
 a) common salt+ water b)sugar + water c)soil + water d)starch + water

7 . A mixture of iron fillings and sulphur is a
a) homogeneous mixture b) heterogeneous mixture c) true solution d) sol

8. When a mixture containing iron fillings and sulphur powder is treated with carbon disulphide
a) Sulphur dissolves in it
b) iron dissolves in it
 c) both sulphur and iron dissolves
 d) no change

9 . A mixture has the following properties 1) the solution is hazy 2 )the particles are suspended in the solution 3) it shows Tyndall effect. The mixture is a
a) True solution b)colloid b) Suspension d) none of these

10. Rahul was rushing with a bottle of iodine , some iodine solution splashed on his white cotton shirt and also on the white table cloth. The stain on the table cloth was yellowish brown while that on his shirt was blue black. The most possible reason is that
a) Shirt was starched after washing
 b) table cloth was starched but not the shirt
 c) shirt has absorbed sweat
d) table cloth had oil patches

11. Following are 5 steps for testing metanil yellow in arhar dal
 i. Make powder of 5 gm of arhar dal
ii. put dal powder in a test tube
iii. add 2-4 drops of conc. HCl and observe the colour change
 iv. filter the content and keep the filtrate separately
v. add 10 ml of water and shake it well the correct sequence is
 a) i,ii,iii,iv,v b) I,iv,v,ii, iii c) I,iii,iv,v,ii

CLASS 9 IS MATTER AROUND US PURE?

1. Which one of the following does not form true solution in water

  a. common salt b. alum c. albumin d. cane sugar

2. Which one of the following forms a colloid in water

  a . common salt b. alum c. albumin d. cane sugar

3.. Which one of the following forms a colloid in water

  a. soil b. sand c. chalk powder d .none of these

4. Which one of the following is highly soluble in water

  a. common salt b. potash alum c. cane sugar d. starch

5. Which one of the following does not form true solution in water at room temperature .

  a.common salt b. alum c. albumin d. cane sugar

6. Which one of the following is least soluble in water

  a. common salt b. potash alum c. cane sugar d. starch

7.Which one of the following can be separated by filtration

  a. common salt and water b. sugar and water

  c. soil and water d. starch and water

8. In which one of the following the particle size is in the range of 0.1 nm to 1.0 nm

  a. true solution b . suspension c. colloid d. none of these

9. Which one of the following forms a colloid in water

  a. sugar b. sand c. chalk powder d. none of these

10.Tyndall effect is observed in which one of the following

  a. true solution b . suspension c. colloid d. none of these

11.Sedimention does not take place in which one of the following

  a. common salt and water b. sugar and water

  c. soil and water d. starch and water

12.Which one will boil at a constant temperature ?

  a. true solution b. colloid c. compound d. each one ..

13.Which represents a constant composition

  a. true solution b. colloid c. suspension d.. none of these

1.  What is tincture of iodine?

2  what kind of mixtures are separated by techniques of crystallization?

3.  State the principle for separation of immiscible liquids?

4.  Why a mixture is an impure substance?

5.  Define aerosol.

6.  What is meant by solubility of a solute?

7.  How to differentiate between sol, solution and suspension?

8.  What is meant by chromatography?

9.  Define emulsion with example.

10.  How to separate ammonium chloride+ sodium chloride. Explain briefly.

class 8
 Class–VIII (CHAPTER-14) CHEMICAL EFFECT OF ELECTRIC CURRENT
Questions 1. Fill the blanks.
(a) Most liquids that conduct electricity are solutions of ________, __________ and __________.
 (b) The passage of an electric current through a solution causes ________ effects.
(c) If you pass current through copper sulphate solution, copper gets deposited on the plate connected to the __________ terminal of the battery.
(d) The process of depositing a layer of any desired metal on another material by means of electricity is called ____________.


2A tester is used to check the conduction of electricity through two liquids. Labelled A and B. it is found that the bulb of the tester glows brightly for liquid A while it glows very dimly for liquid B. you would conclude that
 (i) Liquid A is a better conductor than liquid B
(ii) Liquid B is a better conductor than liquid A
(iii) Both liquids are equally conducting
(iv) Conducting properties of liquid cannot be compared in this manner.
 2. Does pure water conduct electricity? If not, what can we do to make it conducting?
3. In case of fire, before the firemen use the water hoses, they shut off the main electric supply for the area. Explain why they do this.
 4. A child staying in a coastal region tests the drinking water and also the seawater with his tester. He finds that the compass needle deflects more in the case of seawater. Can you explain the reason?
5. Is it safe for the electrician to carry out electrical repairs outdoors during heavy rain pour? Explain.
6. Paheli had heard that rainwater is as good as distilled water. So, she collected some rainwater in a clean glass tumbler and tested it using a tester. To her surprise she found that the compass needle showed deflection. What could be the reason?
7. Prepare a list of objects around you that are electroplated.

chemistry practical page 61 and 63

class 8
CHEMICAL EFFECTS OF ELECTRIC CURRENT

I Fill in the blanks:-

1. A Compound formed by ions is called ________ .

2. The electrode connected to the negative terminal is _________ .

3. Distilled water does not conduct _______.

4. Electroplating is an important use of _______ .

II Choose the correct option:-

1 A liquid metal that conducts electricity :-

(a) Sodium (b) Mercury (c) Lead (d) Gold

2. An atom or a radical that becomes charged is called :-

(a) Radical (b) ion (c) electrode (e) none

3. Metals are extracted from their ores by the process of :-

(a) electroplating (b) electrolysis (c) both (d) none

III Name the following:-

1. An atom that loses an electron

2. Cell used in electrolysis

3. A liquid or a moist paste that has ions in it

IV Define the following:-

1. Electrolysis.

2. Electroplating.

3. Electrolyte.

4. Electrode.

V Draw the following diagrams and label it.

1. Electroplating steel spoons with silver.

2. Flow of ions in an electrolyte.

3. Electrodes.

VI Give reasons for the following:-

1. An acid or ionic salt added to water during the electrolysis of water.

2. Water taps are coated with nickel or chromium.