1. Chemical reaction
1. रासायनिक अभिक्रियाएं एवं समीकरण
(परीक्षा के लिए उपयोगी प्रश्न)
1. What is change ? What are main types of change? How can you say that a change to place?
परिवर्तन क्या है ? यह कितने प्रकार का होता है ? आप कैसे कहेंगे कि परिवर्तन हो रहा है?
2. आप किस प्रकार स्पष्ट करेंगे की अभिक्रिया हो रही है।
How can you clarify that reaction is taking place?
3. What do you mean by the reactants and the product in an equation?
अभिकारक (अभिकर्मक) तथा उत्पाद से आप क्या समझते हैं?
Or
किसी रासायनिक अभिक्रिया में बनने वाले तथा क्रिया करने वाले पदार्थों को क्या कहते हैं? उदाहरण देकर स्पष्ट करो।
What is the name of the substance which react chemical reaction and formed after the reaction. Explain with example.
4. What are the main types of the chemical reaction on the basis of the state of the reactant and product?
अभिकारक (अभिकर्मक) तथा उत्पाद की अवस्था के आधार पर रसायनिक समीकरण कितने प्रकार की होती हैं?
5. What are the main types of the chemical reaction on the basis of the state of involving energythe ? Which one of these called thermite reaction?
ऊर्जा के संबंध के आधार पर रसायनिक समीकरण कितने प्रकार की होती हैं? आप इनमें से किस को उसमें अभिक्रिया कहेंगे।
अथवा
ऊष्माक्षेपी और ऊष्माशोषी अभिक्रिया से आप क्या समझते हैं? उदाहरण देकर स्पष्ट करो।
What do you mean by exothermic and endothermic reaction ? Explain with examples.
6. अभिक्रिया किसे कहते हैं ? यह कितने प्रकार की होती हैं ? प्रत्येक को उदाहरण देकर स्पष्ट करो।
(भौतिक अभिक्रिया और रासायनिक अभिक्रिया)
( ऊष्मा सूची और ऊष्माक्षेपी अभिक्रिया)
What do you mean by the reaction? What are its main types? Clarify with example.
7. रासायनिक अभिक्रिया किसे कहते हैं? यह कितने प्रकार की होती है ?उदाहरण देकर स्पष्ट करो।
What do you mean by the chemical reaction? What are its main types? Explain with example.
8. विकृत गंधिता किसे कहते हैं ? यह क्यों उत्पन्न होती है और इसे किस प्रकार रोका जा सकता है ?
What do you mean by rancidity? Why did it produce and how can we prevent it?
9. प्रति ऑक्सीकारक पदार्थ क्या है और वे विकृत गंधिता को रोकने में किस प्रकार सहायक है?
What are antioxidants ? How they help us to check the rancidity?
10. संक्षारण किसे कहते हैं ? यह किस प्रकार होता है ? इससे क्या क्या हानियां होती है? इसे किस प्रकार रोका जा सकता है?
What do you mean by corrosion? Why did it take place? What are main harms of corrosion? How can we check it?
11. समीकरण क्या है ? यह कितने प्रकार की होती हैं ? संतुलित और असंतुलित समीकरण में क्या अंतर है ? किसी एक समीकरण को संतुलित करके स्पष्ट करो।
What do you mean by equation? What are its main types? What are the differences between the balance and unbalance equation. Explain balancing by the help of a chemical equation.
12. संक्षारण हमेशा हानिकारक नहीं होता , यह लाभदायक भी होता है। कुछ उदाहरण देकर स्पष्ट करो।
Corrosion is not always harmful. Is it useful also? Explain with example.
Q. 13. विभिन्न धातुओं पर बनने वाली संक्षारणीय परतों के नाम उनके रंग और रसायनिक सूत्रों के साथ लिखिए।
Write the names of the corrosive layers formed on various metals, along with their color and chemical formulas.
Ans.
* Green coating of copper is basic copper carbonate CuCO3.Cu(OH)2
* Black coating of silver is silver sulphide AgS
* Reddish brown coating of iron is hydrated iron oxide Fe2O3.nH2O
01. Some important questions based on Lesson Number 1.
Part - 01
1) What is combination reaction ? State one example giving balanced chemical equation for the reaction.
2) What is combination reaction ? State one example giving balanced chemical equation for the reaction.
Q. 3) 2g of Lead Nitrate powder is taken in a test tube. The test tube is heated over a flame. answer the following
a) State the colour of the fumes evolved and the residue left.
b) Name the type of the chemical reaction that take place is treating its balance chemical equation.
Ans.
2Pb(NO3)2 = heated => 2PbO + 4NO2 (brown fume) + O2
a) brown colour fume of nitrogen oxide gas ( NO2) are evolved residue left is white lead oxide (PbO).
b) Lead Nitrate 2Pb(NO3)2 is broken down into you lead oxide (PbO), nitrogen dioxide ( NO2) and oxygen (O2) after heating so it is thermal decomposition reaction.
Q. 4) What is is corrosion ? Why aluminium sheets do not corrode easily write two necessary conditions for corrosion to take place.
Ans. Iron and steel also rust when they come into contact with water and oxygen. They rust faster in salty water or acid rain.
Aluminium does not corrode easily, because its surface is protected by a layer of aluminium oxide (Al2O3).
There are three main components necessary for corrosion to occur:
1. Metal (example: iron)
2. Oxygen (usually from the atmosphere)
3. An electrolyte (usually water).
So Water and oxygen is important for corrosion.
Q. 5) Vinjeet heated sulphur powder in a China dish and collected the gas evolved.
a) give the equation of the reaction for reading of the sulphur
b) Write the effect of the gas on red litmus solution and blue litmus solution
c)Give the type of ore who is heating will evolve the gas.
Ans.
a) S + O2 (air) = heated => SO2 (g)
b) Sulphur dioxide gas is acidic in nature so it has no effect on the red litmus paper and this gas turns blue litmus into red.
c) sulphide ore.
Q. What do you mean by the thermit reaction, explain with example. is burning respiration root meaning and decomposing are exothermic reaction.
Q.
Q.
S2 –S1)
Some Other Important Questions
S.O.I.Q
Q. In the electrolysis of water:
a. Name the gas collected at the cathode and anode respectively.
b. Why is volume of gas collected at one electrode double than that at the other? Name this gas.
c. How will you test this gas?
Ans :
a. Hydrogen is collected at the cathode, oxygen is collected at the anode.
b. It is because H2O contains hydrogen and oxygen in the ratio 2:1.
c. Bring a burning matchstick near the gas, H2.
89. State one example each characterised by following along with suitable chemical equation.
a. Change in state,
b. Evolution of gas,
c. Change in temperature.
Ans :
a. Change in state:
AgNO3(aq) + HCl(aq) → AgCl(s) + HNO3(aq)
b. Evolution of gas:
CaCO3 + 2HCl dil →CaCl(aq) +H2O CO2
c. Change in temperature:
d. CH4
(g) + 2O2
(g) $ CO2
(g) + 2H2
O(l) + Heat
Q. 1. In electrolysis of water, why is the volume of gas collected over one electrode double that of gas
collected over the other electrode.
Ans : Water contains hydrogen and oxygen in the ratio of 2 : 1, that is why volume of H2 is double than that of oxygen.
Q. 2. What can be seen when a strip of copper metal is placed in a solution of silver nitrate?
Ans : The solution will become blue, shiny silver metal will get deposited.
Cu(s) + 2AgNO3(aq) → Cu(NO3)2(aq) + 2Ag(s)
Q. 3. State one industrial application of reduction process.
Ans : Reduction process is used in the extraction of metals e.g.,
ZnO(s) + C(s) → Zn(s) + O2(g)
Q. 4. Which one of the following is a chemical change? Give reason also.
(a) Burning of wax
(b) Melting of wax
Ans : Burning of gas is a chemical change because new products with new properties will be formed on
burning.
5. Which one is a chemical change:
Rusting of iron or melting of iron?
Ans : Rusting of iron is a chemical change.
6. State one basic difference between a physical change
and a chemical change.
Ans : [CBSE 2014, 2011]
In a physical change, no new substance is formed.
In a chemical change, new substance(s) with new
properties is/are formed.
7. Name the oxidising and reducing agent in the following
reaction:
CuO + H2 $ Cu + H2
O
Ans : [CBSE 2013]
CuO is oxidising agent H2
is reducing agent.
8. Write a complete balanced chemical equation for the
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