Question

30. A metal 'X', when ignited, burns with a bright white light and forms a white powder. When
this white powder dissolves in water it turns red litmus to blue.
(i) Identify metal 'X' and the white powder formed.
(ii) Write down the balanced chemical equation of the reaction involved when metal 'X' is
ignited.
(iii) Why does the solution of the formed white powder, in water, turn red litmus blue?
(iv) Name two metals which do not react with water at all.​

Answer 1

Answer:

Explanation:

Magnesium ribbon burns with dazzling white light, once treated to its ignition temperature. The white powder formed is Magnesium oxide which dissolves in water to give a basic solution which turns red litmus blue. Thus 'x' is Mg and 'y' is MgO

Answer 2

Answer:

a) Metal X is Magnesium (Mg).

b) Powder Y is Magnesium oxide, (MgO).

c) The substance with which metal X combines to form powder Y is Oxygen (of air), O  

2

​

 

d) Substance Z is Magnesium hydroxide Mg(OH)  

2

​

. Used as an antacid to relieve indigestion.

e) 2Mg+O  

2

​

→2MgO

                              powder

Explanation:

OK