Selina solutions for Concise Chemistry [English] Class 8 ICSE chapter 6 - Chemical Reactions [Latest edition]

 Define a chemical reaction.

 What happens during a chemical reaction ?

What do you understand by a chemical bond ?

Give one example each of which illustrates the following characteristics of a chemical reaction:

evolution of a gas

Give one example each of which illustrates the following characteristics of a chemical reaction:

change of colour

Give one example that illustrates the following characteristics of a chemical reaction:

Change in state

How do the following help in bringing about a chemical change?

pressure.

How do the following help in bringing about a chemical change?

light.

How do the following help in bringing about a chemical change?

catalyst .

How do the following help in bringing about a chemical change?

heat. 

Define; catalyst.

 What are (i) positive catalysts and (ii) negative catalysts? Support your answer with one example for each of them.

Name three biochemical catalysts found in the human body.

What do you observe when dilute sulphuric acid is added to granulated zinc?

What do you observe when a few pieces of iron are dropped in a blue solution of copper sulphate?

What do you observe when silver nitrate is added to a solution of sodium chloride?

What do you observe when ferrous sulphate solution is added to an aqueous solution of sodium hydroxide.

What do you observe when when dilute sulphuric acid is added to barium chloride solution ?

Complete and balance the following chemical equations:

N₂ + O₂  →

Complete and balance the following chemical equations:

`"H"_2"S"` + `"CI"_2`  `→`  

Complete and balance the following chemical equations

Na + H₂ O →

Complete and balance the following chemical equations

NaCI + `AgNO_3`  `→`

Complete and balance the following chemical equations:

Zn + `"H"_2"SO"_4`  `→`

           (dil)

Complete and balance the following chemical equations:

Fe `"SO"_4`  + NaOH  `→`

   (aq.)          (aq.)

Complete and balance the following chemical equations:

\[\ce{Pb(NO3)2->[heat]}\] _________

Complete and balance the following chemical equations:

Ba`"CI"_2`   +  `"H"_2"SO"_4`   `→`

    (aq.)           (aq.)

 Fill in the blank

A reaction in which two or more substances combine to form a single substance is called a ............ reaction.

Fill in the blanK

 A .............is a substance which changes the rate of a chemical reaction without undergoing a chemical change.

 Fill in the blank.
 The formation of gas bubbles in a liquid during a reaction is called ......................

Fill in the blank.

The reaction between an acid and a base is called ..................

 Fill in the blank .

Soluble bases are called ............

Fill in the blank.

The chemical change involving iron and hydrochloric acid illustrates a ...............reaction.

Fill in the blank

In the type of reaction called ....................................., ions two compounds exchange their positive and negative radicals ions respectively.

Fill in the blank

 A catalyst either ................or ............... the rate of a chemical change but itself remains ............... at the end of the reaction.

 Fill in the blank

The chemical reaction between hydrogen and chlorine is a ................ reaction

Fill in the blank

When a piece of copper is added to silver nitrate solution, it turns ............in colour.

Classify the following reaction as combination, decomposition, displacement, precipitation and neutralization. Also balance the equation.

\[\ce{CaCO3_{(s)} ->[heat]CaO_{(s)} + CO2_{(g)}}\]

Classify the following reaction as combination, decomposition, displacement, precipitation and neutralization. Also balance the equation.

\[\ce{Zn_{(s)} + H2SO4 -> ZnSO4_{(s)} + H2_{(g)}}\]

Classify the following reaction as combination, decomposition, displacement, precipitation and neutralization. Also balance the equation.

\[\ce{AgNO3_{(aq)} + NaCl_{(aq)}-> AgCl_{(s)} + NaNO3}\]

Classify the following reaction as combination, decomposition, displacement, precipitation and neutralization. Also balance the equation.

\[\ce{NH3_{(g)} + HCl_{(g)} -> NH4Cl_{(s)}}\]

Classify the following reaction as combination, decomposition, displacement, precipitation and neutralization. Also balance the equation.

\[\ce{CuSO4_{(aq)} + H2S_{(s)} -> CuS_{(s)} + H2SO4_{(l)}}\]

Classify the following reaction as combination, decomposition, displacement, precipitation and neutralization. Also balance the equation.

\[\ce{Zn_{(s)} + CuSO4_{(aq)} -> ZnSO4_{(aq)} + Cu_{(s)}}\]

Classify the following reaction as combination, decomposition, displacement, precipitation and neutralization. Also balance the equation.

\[\ce{Ca_{(s)} + O2_{(g)}->[heat] CaO_{(s)}}\]

Classify the following reaction as combination, decomposition, displacement, precipitation and neutralization. Also balance the equation.

\[\ce{NaOH + HCl -> NaCl + H2O}\]

Classify the following reaction as combination, decomposition, displacement, precipitation and neutralization. Also balance the equation.

\[\ce{KOH + H2SO4 -> K2SO4 + H2O}\]

Define precipitation.

Define neutralization.

Define catalyst.

Explain the following type of chemical reaction, giving two examples for it:

Combination reaction

Explain the following type of chemical reaction, giving two examples for it:

Decomposition reaction

Explain the following type of chemical reaction, giving two examples for it:

Displacement reaction

Explain the following type of chemical reaction, giving two examples for it:

Double displacement reaction

Write the missing reactants and products and balance the equations.

NaOH + ............... `→` NaCI + ...................

Write the missing reactants and products and balance the equations.

\[\ce{KClO3 ->[heat]}\] ___________+ ____________

Write the missing reactants and products and balance the equations.

................+ HCI `→` NaCI + `"H"_2"O"` + .........................

How will you obtain Magnesium oxide from magnesium.

Also give balanced equations for the reactions

How will you obtain  Silver chloride from silver nitrate.

Also give balanced equations for the reactions

How will you obtain  Nitrogen dioxide from lead nitrate.
Also give balanced equations for the reactions

How will you obtain Zinc chloride from zinc.

Also give balanced equations for the reactions

How will you obtain Ammonia from nitrogen.
Also give balanced equations for the reactions

What do you observe when Iron nail is kept in copper sulphate solution for sometime.

What do you observe when Phenolphthalein is added to sodium hydroxide solution.

What do you observe when Blue litmus paper is dipped in dilute hydrochloric acid.

What do you observe when Lead nitrate is heated.

What do you observe when Magnesium ribbon is burnt in oxygen.

What do you observe when Ammonia is brought in contact of hydrogen chloride.gas.

Give reason .

A person suffering from acidity is advised to take an antacid.

Give reason.

Acidic soil is treated with quick lime.

Give reason.

Wasp sting is treated with vinegar.

What is meant by the metal reactivity series ? State its importance, (any two points).

What are oxides ? 

Give two examples Basic oxide .

Give two examples of  oxides.

Acidic oxide.

Give two examples of  oxides.

Amphoteric oxide

Give two examples of oxides.

 Neutral oxide

Define exothermic reactions. Give two examples of each.

Define  endothermic reactions. Give two examples of each.

State the effect of an endothermic reaction.

State the effect of  an exothermic reaction on the surroundings.

What do you observe when an acid is added to a basic solution.

What do you observe when ammonium chloride is dissolved in water.