Unit I: Chemical Substances - Nature and Behaviour

NCERT Solutions -Class 10 -Chemical Reactions and Equations

 

Chemical Reaction

When two or more substance react with each other to form one or more new substance this is called chemical reaction

 

The substances which reacts with each other in a chemical reaction are known as reactants they are generally written on the left hand side of the equation

 

The substances which are formed in a chemical reaction are known as product they are generally written on the right hand side of the equation

 

Chemical reactions can be of different types

 

1) Combination reaction-- when two or more substances combine together to form a new substance is called combination reaction

 

Symbolically

 

A+B ------C

 

Two substances A and B are combined together to form a new substance C

 

Example

 

H2+Cl2------2HCl

 

2) Decomposition reaction-- when a substance decomposes into two or more substances is called decomposition reaction

 

Symbolically

 

C---A+B

 

The compound C decomposes to two compounds A and. B

Example

 

ZnCO3------Zn + CO2

 

 

The composition of a compound can be done by either of the methods

 

 --- by thermal decomposition 

--- by electrolysis 

-----by photolysis reaction 

 

3) Displacement Reaction 

 

When an element of a compound displaces by another element during a chemical reaction is known as displacement reaction

 

Symbolically

 

AB+C-----AC+B 

 

In above equation element C displaces element B of the compound AB so this type of reaction is known as displacement reaction

 

2HCl+Mg------MgCl2 + H2

 

 

4) Double displacement reaction

 

When elements of compounds and exchanged each other in a chemical reaction what is known as double displacement reaction

 

Symbolically

 

AB+CD-----AD+BC

 

In the above reaction elements of the compound AB and elements of the compounds CD are exchange together to form a compounds AD and BC

 

2KBr+BaI2-------2KI. + BaBr2

 

Types of reactions positive ion of one compound reacts with negative ions of another compound similarly in negative ions of the first compound combines with positive

Redox Reaction

The reaction in which there is a oxidation and reduction both occurs is known as red oxide reaction in this type of reaction there is gain of electron in one element and loss of electrons in an atom

 

The element which gains electrons undergoes oxidation reaction it can also be defined as addition of oxygen is known as oxidation reaction

 

The element which loses electron undergoes reduction reaction or in other words addition of hydrogen is known as reduction reaction

 

The substance which undergoes oxidation is known as reducing agent

The substance which undergoes reduction is known as oxidising agent

Limiting Reagent

The substance which consumes completely in a chemical reaction is called limiting reagent generali on limiting reagent decide the extent of a chemical reaction

 

 

Carbon and its compounds

Sample paper

• 1)What is catenation
• 2)What are isomers write the isomers of butane
• 3) What is the mean by homologous series explain with example
• 4) What is the difference between saturated and unsaturated compounds give two examples of each
• 5) How many number of bonds are present in alkane alkene and alkyne
• 6) What is the general formula of alkyl group and cycloalkanes
• 7) Write a formula of
• cyclopentane
• Propyne
•  butanol 
• Benzene
• 8) What are soaps explain its structure and cleansing action of soap
• 9) what do the detergent forms when they mix and water and what is the difference between detergent and soap
• 10) What are the products formed
• When the flame burns with blue flame and
• when the bus with yellow frame

11)

What is difference between combustion and oxidation

12) what do you mean by saponification explain with reaction

13) what is the eastrification give the chemical reaction and what are the products formed

14) what are addition and substitution reactions give one example of each

15) explain the tetravalency of carbon what is the reason why there are lot of carbon compounds are made by the carbon

 

Periodic classification of elements

Sample paper

1. What is the mendeleev periodic law?
2. What is modern periodic law?
3. What is the name given to the horizontal rows and vertical column
4. What are the drawbacks of the mendeleev periodic law
5. How many groups and periods are found in the mendeleev periodic law
6. Why noble gases are not present in the mendeleev periodic table
7. How many groups and periods are found in the long form of table
8. What is ionization enthalpy why the second ionization enthalpy of alkali metals is greater than the first ionization enthalpy
9. Why the atomic radius of chlorine is less than atomic radius of sodium
10. What is electronegativity how does electronegativity variates in periodic table from moving top to bottom
11. Why hydrogen is placed at the top of the periodic table
12. Who discover the atomic number
13. What are diagonal elements
14. What is electron affinity how does it changes when we move from left to right in the periodic table
15. Why noble gases do not react with any other elements

 

 

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