Question

(a) Write chemical equations for the following reactions:
(i) Calcium metal reacts with water.
(ii) Cinnabar is heated in the presence of air.
(iii) Manganese dioxide is heated with aluminium powder.
(b) What are alloys? List two properties of alloys.

Answer 1

Answer:

(i)Ca+H2O ⇒ Ca(oh)2 + h2

(ii)  HgS+302 ⇒ 2Hgo + 2SO2

(iii) 3MnO3 + 4Al⇒ 3Mn +2Al2O3

 (b) an alloy is a homogeneous mixture of two or more metals , or a metal and a nonmetal

the electrical conductivity and melting point of an alloy is less than that of the pure metal

Explanation:

Answer 2

(a)  Chemical equations for the given reactions are as follows.

(i)  $Ca + H_{2}O \rightarrow Ca(OH)_{2} + H_{2}$

(ii) $2HgS + 3O_{2} \rightarrow 2HgO + 2SO_{2}$

(iii)  $3MgO_{2} + 4Al \rightarrow 3Mn + 2Al_{2}O_{3}$

(b)  When two or more metallic elements are combined together to make certain metal with greater strength and resistance to corrosion then this type of metal is known as an alloy.

Explanation:

(a) Chemical equations are defined as the equations written in symbolic form in order to represent a chemical reaction in the form of symbols and chemical formula.

So, chemical equations for the given equations are represented as follows.

(i)  $Ca + H_{2}O \rightarrow Ca(OH)_{2} + H_{2}$

(ii) $2HgS + 3O_{2} \rightarrow 2HgO + 2SO_{2}$

(iii)  $3MgO_{2} + 4Al \rightarrow 3Mn + 2Al_{2}O_{3}$

(b)   When two or more metallic elements are combined together to make certain metal with greater strength and resistance to corrosion then this type of metal is known as an alloy.

Two properties of alloys are as follows.

1.  They are resistant to corrosion.

2.  They are less malleable and ductile.

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