Question 18Which of the following are combination reactions-i 2KClO3 Heat- 2KCl - 3O2ii MgO - H2O-MgOH2iii 4Al - 3O2 - 2Al2O3iv Zn - FeSO4 -ZnSO4 - Fea i and iiib iii and ivc ii and ivd ii and iii

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Standard VII

Chemistry

Combination Reaction

Question 18Wh...

Question

Question 18
Which of the following are combination reactions?

(i) $2 {KClO}_{3} Heat \to 2 KCl + 3 O_{2}$
(ii) $MgO + H_{2} O \to {Mg(OH)}_{2}$
(iii) $4 Al + 3 O_{2} \to 2 {Al}_{2} O_{3}$
(iv) $Zn + {FeSO}_{4} \to {ZnSO}_{4} + Fe$

(a) (i) and (iii)
(b) (iii) and (iv)
(c) (ii) and (iv)
(d) (ii) and (iii)

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Solution

A reaction in which two or more reactants react together to form a single product is called a combination reaction. In reaction (ii), $MgO$ and $H_{2} O$ are combining to form ${Mg(OH)}_{2}$ and in reaction (iii), $Al$ and $O_{2}$ are combining to form ${Al}_{2} O_{3}$ .

In reaction (i), $2 {KClO}_{3}$ is undergoing thermal decomposition, hence it is a decomposition reaction whereas reaction (iv) is a single displacement reaction.

So, Option (d) is correct.

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Q. Question 18
Which of the following are combination reactions?

(i)

2 {KClO}_{3} Heat \to 2 KCl + 3 O_{2}

(ii)

MgO + H_{2} O \to {Mg(OH)}_{2}

(iii)

4 Al + 3 O_{2} \to 2 {Al}_{2} O_{3}

(iv)

Zn + {FeSO}_{4} \to {ZnSO}_{4} + Fe

(a) (i) and (iii)
(b) (iii) and (iv)
(c) (ii) and (iv)
(d) (ii) and (iii)

Q. Which of the following is/are combination reaction(s)?
(i)

2 K C l O_{3} H e a t \to 2 K C l + 3 O_{2}

(ii)

M g O + H_{2} O \to M g (O H)_{2}

(iii)

4 A l + 3 O_{2} \to 2 A l_{2} O_{3}

(iv)

Z n + F e S O_{4} \to Z n S O_{4} + F e

Which of the following are combination reactions?

i) 4K + O₂ → 2K₂O

ii) CuSO₄+ 2NH₄OH → (NH₄)₂SO₄+ Cu(OH)₂

iii) 2ZnS + 3O₂ → 2ZnO + 2SO₂

iv) Na₂O + H₂O → 2NaOH

Question 10

Consider the list of terms given below:
(i) Tsunami
(ii) Landslides
(iii) Floods
(iv) Lightning
Earthquakes can cause
(a) (i), (ii) and (iii)
(b) (ii) and (iv)
(c) (ii), (iii) and (iv)
(d) (iii) and (iv)

Compounds showing cannizaro's reaction are
(i) $C H_{3} C H_{2} C H O$ (ii) $C H C l_{2} C H O$ (iii) $(C H_{3})_{3} C - C H O$ (iv) $C_{6} H_{5} C H O$

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Combination Reaction

Standard VII Chemistry

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Question 18 Which of the following are combination reactions? (i) 2KClO3Heat→2KCl+3O2 (ii) MgO+H2O→Mg(OH)2 (iii) 4Al+3O2→2Al2O3 (iv) Zn+FeSO4→ZnSO4+Fe (a) (i) and (iii) (b) (iii) and (iv) (c) (ii) and (iv) (d) (ii) and (iii)