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All ores are minerals but all minerals are not ores. Justify.
For two statements are given-one labelled Assertion (A) and the other labelled Reason (R). Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below:
(a) Both A and R are true, and R is correct explanation of the assertion.
(b) Both A and R are true, but R is not the correct explanation of the assertion.
(c) A is true, but R is false.
(d) A is false, but R is true.
Assertion: C and N do not react with dil. HCI and dil. H2SO4.
Reason: Metals do not react with dil. HCI and dil. H2SO4.
For two statements are given-one labelled Assertion (A) and the other labelled Reason (R). Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below:
(a) Both A and R are true, and R is correct explanation of the assertion.
(b) Both A and R are true, but R is not the correct explanation of the assertion.
(c) A is true, but R is false.
(d) A is false, but R is true.
Assertion: Aluminium oxide and zinc oxide are acidic in nature.
Reason: Amphoteric nature means that substances have both acidic and basic character.
Why is titanium called a strategic metal? Mention two of its properties which make it so special.
Read the following and answer any four questions from (i) to (v).
An element is a pure substance made up of same kind of atoms. At present, nearly 118 elements are known but all of them do not occur free in nature, some of them have been synthesized by artificial methods. Based on their properties, they are mainly classified as metals and non-metals. Metals are those elements which lose electrons and form positive ions i.e., they are electropositive in nature. They are generally hard, good conductors of heat and electricity, malleable, ductile and have striking luster. They have a significant role to play in our daily life.
(i) Metals which are of vital importance to the national Défense, energy and industry sector are called strategic metals. Which of the following is a strategic metal?
(a) Titanium.
(b) Zirconium.
(c) Manganese.
(d) All of these.
(ii) Which metal is the best conductor of electricity?
(a) Silver.
(b) Platinum.
(c) Nickel.
(d) Iron.
(iii) Which of the following metals is not a coinage metal?
(a) Copper.
(b) Silver.
(c) Iron.
(d) Gold.
(iv) Which of the following are the most malleable metals?
III. Potassium.
(a) (I) and (IV)
(b) (II) and (III)
(c) (III) and (IV)
(d) (II) and (IV)
(v) Identify the correct statement(s).
III. Metals do not conduct electricity.
(a) (I) and (III)
(b) (I) and (II)
(c) (III) and (IV)
(d) Only (II)
Which important properties of aluminium are responsible for its great demand in industry?
(a) Which of the following metals would give hydrogen when added to dilute hydrochloric acid?
(b) Explain why do surfaces of some metals acquire a dull appearance when exposed to air for a long lime.
Out of zinc and iron, which evolves hydrogen more readily on reacting with dilute HCl?
Name an alloy of
Aluminium used in construction of air crafts.
Lead in joining metals for electric welding.
Copper used in household vessels.