Question

I) Fill in the blanks: [Write the full statement along with its answer]
(a) In______________________ change no new substance is formed.
(b) A foul smelling spoiled food is a_______________________ change.
(c) Properties such as shape, size, colour and state of a substance are called____________ properties.
(d) Turning of lime water to milky is a standard test of_________________________ gas. (e) A chemical change is also called a_________________________
(f) Photosynthesis is an example of __________________________change.
(g) Burning of any substance is a____________________________change.
(h) Conditions for rusting of iron is ____________________and____________________ (i) The chemical name of vinegar is________________________________
II) Choose the correct answer: [Write the statement and then write correct option]
(A) Galvanisation is a process used to prevent the rusting of which of the following? (a) Iron
(b) Zinc
(c) Aluminium (d) Copper
(B) Which of the following statement is incorrect for a chemical reaction? (a) Heat may be given out but never absorbed.
(b) Sound may be produced.
(c) A colour change may take place.
(d) A gas may be evolved
(C) The gas we use in the kitchen is called Liquefied Petroleum Gas – LPG. In the cylinder it exists as a liquid, when it comes out from the cylinder it becomes a gas [Change A], then it burns [Change B]. The following statements pertain to these changes. Choose the correct one
(a) Process A – Chemical change
(b) Process B – Chemical change
(c) Both process A and B are chemical changes (d) None of these processes is a chemical change
(D) Two drops of dilute sulphuric acid were added to 1 g of copper sulphate powder and then small amount of hot water was added to dissolve it (step I). On cooling, beautiful blue coloured crystals got separated (step II). Step I and step II are:
(a) physical and chemical changes respectively. (b) chemical and physical changes respectively.
(c) both physical change. (d) both chemical change.
(E) If you leave a piece of iron in the open for a few days, it acquires a film of brownish substance, called rust.
(a) Do you think rust is different from iron?
(b) Can you change rust back into iron by some simple method? (c) Do you think formation of rust from iron is a chemical change? (d) Give two other examples of a similar type of change
III) Classify the following as a chemical or physical change
a. Photosynthesis
b. Dissolving sugar in water
c. Burning of coal
d. Beating aluminium to make aluminium foil
e. Melting of wax
f. Digestion of food
IV) State True or False
a. If wind blows from land to the ocean, then it is a day time
b. A very high pressure system with very high speed wind surrounding it forms a
cyclone
c. The coast line of India is not vulnerable to cyclones
d. Warm is lighter than cool air
V) Answer the following:
1. Carefully read the experiments given below. Identify the type of reaction taking place in each experiment and write the difference between each of them. Also, write a balanced chemical equation each type of reaction.
a. Experiment-1: A piece of magnesium ribbon was burnt on a flame. As a result,
white powder or ash is formed.
b. Experiment-2: When an iron nail was dipped in the copper sulphate solution, the
blue copper sulphate solution turned green and a brown deposit formed on the
iron nail.
c. Experiment-3: A solution of sodium chloride was dissolved in silver nitrate
solution. As a result, white cloudy compound was formed.
d. Experiment-4: Whereas when, sulphuric acid was mixed with sodium hydroxide
solution, water and sodium sulphate salt were formed.
Q1) Answer the following:
1. When food gets spoiled, it produces a foul smell. Shall we call this change a chemical change?
2. Is neutralisation reaction a chemical change? Explain
3. What do you understand by a Redox reaction? Explain with an example.
4. When a candle burns, both physical and chemical changes take place. Identify these changes. Give another example of a familiar process in which both the chemical and physical changes take place
5. Define
a. Endothermic reaction and b. exothermic reaction
6. Why is it advisable not to shut all the doors and windows during a storm? 7. Explain how lightning takes place
8. Describe / Define the following:
a. Tornado: b. Cyclone: c. Storm:
9. I kept an empty bottle made up of plastic inside a refrigerator. After a few hours, when I opened the refrigerator, I found the bottle collapsed. Explain
10. When strong / high speed wind blows, an umbrella held upright at times get upturned. Explain the reason.

Answer 1

Answer:

fill in the blanks

1.physical

2.chemical

3.physical

4.carbondioxide

5.chemical reaction

6.chemical

7.chemical

8.exposure to air and moisture

9.acetic acid

choose the correct option

1.(a) iron

2.(a)heat may always be given out but never absorbed.

3.(c)both the processes A and B are chemical changes.

4.(c)both physical change

5.(a)yes bcoz rust is formed when iron reacts with oxygen and moisture and rust is a hydrated oxide of iron i.e; a compound form of iron.

(b)no bcoz rust is formed as a result of a chemical reaction of iron with oxygen and moisture and thus cannot be brought back to its original state with simple physical methods.

(c)yes it is a chemical change bcoz rust is entirely different from that of iron in terms of its physical and chemical properties and its chemical composition.

(d)examples of a chemical change are: cooking of rice, burning of paper.

classify as physical or chemical changes

1.chemical change

2.physical change

3.chemical change

4.physical change

5.physical change

6.chemical change

state true or false

1.False

2.True

3.False

4.True

I HOPE THIS HELPS YOU...