Additional Questions With Solutions:
Q1: Write three chemical properties of metals.
Ans: Three chemical properties of metals.
(i)All metals combine with oxygen to form metal oxides.
(ii)Metals react with water and produce a metal oxide and hydrogen gas.
(iii)Metals reacts with acids to give a salt and hydrogen gas.
Q2: Write three physical properties of metals.
Ans: Three physical properties of metals.
(i)Metals are ductile.
(ii)Metals are malleable.
(iii)Metals are sonorous.
Q3: What is amphoteric oxides? Give to examples.
Ans: The metals oxides which react with both acids as well as bases to produce salt and water and show both acids as well as basic behaviour are known as amphoteric oxides. Ex.- aluminium oxide and zinc oxide etc. q
Q4: Why are sodium or potassium kept immersed in kerosene oil?
Ans: Sodium or potassium reacts so vigorously that they catch fire if kept in open. Hence to protect them and to prevent to accidental fire they are kept immersed in kerosene oil.
Q5: The reaction metal X and Fe2 O3 is highly exothermic and is used to join railway.
(a) Identify metal X and name the reaction.
(b) Write the chemical equation of its reaction with fe2 O3.
Ans:
(a)X is (Al) Aluminium. Thermit Reaction.
(b)Fe2O3 (s) + 2Al(s) 2Fe(l) + Al2O3(s) + (Heat)
Q6: A metal X react with oxygen to form a blackish thin layer of oxide coat which protects itself to further corrosion.
(i)Identify the metal X.
(ii)What is called such a metal oxide.
(iii)What does it give to react with sodium hydroxide write its chemical equation.
Ans:
(i)Metal X is aluminium.
(ii)Aluminium oxide is called amphoteric oxides.
(iii)It react with sodium hydroxide gives sodium aluminate and water.
Q7: What is aqua regia?
Ans: Aqua regia is freshly prepared mixture of concentrated hydrochloric acid and concentrated nitric acid in the ratio of 3: 1. It is used to dissolve gold and clean the ornaments.
Q8: Why are the ornaments made of gold, silver and platinum?
Ans: Gold, silver and platinum have less reactivity so they don’t react with water and oxygen that cause corrosion. Hence the ornaments are made of gold, silver and platinum.
