Write names of the following salts and also classify them as acidic, basic or neutral:
i) K2SO4 ii) Mg (NO3)2 iii) Na2CO3
Answers
Answer:
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Explanation:
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Answer:
Write down the formulae of the following:
a) Formic Acid
b) Oxalic Acid
1 m
ii) Write any two uses of sugar charcoal.
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iii) Write chemical equations for the following:
a) Charcoal reduces steam to water gas
b) When heated with hydrogen, charcoal forms methane.
1 m
Q.7 i) Write down the formulae of the following crystals
a) Quicklime
b) Glauber’s salt
1 m
ii) What are allotropes? Explain any one in detail.
1 m
iii) Write down any two equations to show that CO is a
reducing agent.
1 m
Explanation:
Write down the formulae of the following:
a) Formic Acid
b) Oxalic Acid
1 m
ii) Write any two uses of sugar charcoal.
1 m
iii) Write chemical equations for the following:
a) Charcoal reduces steam to water gas
b) When heated with hydrogen, charcoal forms methane.
1 m
Q.7 i) Write down the formulae of the following crystals
a) Quicklime
b) Glauber’s salt
1 m
ii) What are allotropes? Explain any one in detail.
1 m
iii) Write down any two equations to show that CO is a
reducing agent.
1 m
Q.1 Name the following:
2.5 m
a) The temperature at which white hot coke converts into water gas.
b) The formulae of Benzene.
c) The temperature at which Graphite melts.
d) The random movement of particles.
e) The density of diamond.
Q. 2 Match the following:
2.5 m
a) Buckminsterfullerene
i)
CaO(s) + CO
2(g)
b) Quicklime
ii)
Rocket Fuel
c) Decomposition of CaCO3
iii) CaO
d) Weak Electrolytes
iv) C60
e) Liquid Hydrogen
v)
NH4OH
Q. 3 Balance the following equations:
2.5 m
a) Fe2O3+H2 → Fe+H2O
b) Mg + CO2 → MgO + C
c) SO2+NaOH → Na2SO4 + H2O
d) Al2O3 + H2SO4 → Al2 (SO4)3 + H2O
e) NaHCO3 + H2SO4 → Na2SO4 + H2O + CO2
Q. 4 Define:
2.5 m
a) Reducing Agent
b) True Solution
c) Anhydrous Substances
d) Hygroscopic Substances
e) Deliquescent substances
SECTION-B [10 Marks]
(Attempt all questions)
Q. 5 Observe the given figure properly and answer the following questions:
i) Define the process taking place in the above picture.
1 m
ii) Also write
the equations that take place at the cathode and anode.
2 m
iii) With the help of any two equations show that hydrogen is a reducing
agent.
1 m Class – 8
SECTION – A (10 marks)
Time-1½ hrs.
Q. 1. Fill in the blanks
(5 x ½ = 2 ½)
1. _________ state of matter can undergo all the three thermal expansion.
2. _________ is the loudest sound tolerated by human ear.
3. We can replace electric bulb by __________ to conserve electricity.
4. A switch is connected to the _______ wire.
5. An instrument used to detect and measure the electric charges is called ______.
Q. 2. State whether the statements are true or false. Correct the wrong statement. (2)
1. Sagging of telephone and electric wires is due to superficial expansion.
2. Saxophone is an example of percussion.
3. The direction of flow of the conventional current in a circuit is from negative to
positive terminal of the cell.
4. A fuse is always connected in the live wire and in parallel with the electric circuit.
Q. 3. Define the following terms.
(1)
1. MCB
2. Thermal equilibrium
Q. 4. Match the following.
(2.5)
1. Thermoswitches. a.
Mouth organ
2. Ebonite. b.
Sitar
3. Reed instrument.
c.
Earth
4. Green colour. d.
Brass and iron
5. Tantu vadya. e.
Negative charges
Q. 5. Numerical Problems.
(2)
1. A vacuum cleaner is rated at 650 watt. How much electrical energy will it consume in
13 days if it is used for 1.5 hours daily?
2. There are 5 tube lights of 18 watt each, 3 fans of 60 watt each, a computer of 80 watt
and an air conditioner of 1 kW in an office. Calculate the electricity bill for the month of July if these appliances are used for 7 hrs daily. Take the cost of 1 unit of energy as
Rs. 2.50.
SECTION – B (Attempt all questions)
Q. 6. 1.
What are the laws of electrostatics?
(1)
2.
Why a man’s voice is more shrill than a woman’s voice?
(1)
3.
What are the factors affecting evaporation?
(1)
Q. 7. 1.
How will you find out the nature of charge on a body using a gold leaf
electroscope?
(1)
2.
What is meant by earthing of an appliance?
(1)
3.
Why do you pour hot water over the neck of a glass bottle to remove a stuck
stopper?
(1)
Q. 8. 1.
How does amplitude and loudness relate to each other?
(1)
2.
What precautions should you take to protect yourself from lightning?
(2)
3.
Why wet person will get severe shock when touched on an electrical appliance?
(1)