Tag: elements and compounds

Quizzes (9) Questions (54)

Questions Related to elements and compounds

Multiple choice chemistry elements and compounds alloys and their properties metals, alloys and crystals chemical bonding and structure

An alloy of copper, silver and gold is found to have copper constituting the ccp lattice. If silver atoms occupy the edge wares and gold is resent at a body centre. the alloy has a formula?

  1. $ Cu _{4}Ag _{2}Au $
  2. $ Cu _{4}Ag _{4}Au $
  3. $ Cu _{4}Ag _{3}Au $

  4. CuAgAu
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

In a ccp lattice, Cu atoms at corners and faces give 4 atoms per unit cell. Silver atoms at edge centers (12 edges * 1/4 = 3 atoms). Gold at body center (1 atom). Formula: Cu4Ag3Au.

Multiple choice chemistry elements and compounds alloys and their properties metals, alloys and crystals chemical bonding and structure

Which of the following is an alloy?

  1. Silver

  2. Gallium
  3. $22$ carat gold
  4. $24$ carat gold
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

22 karat gold contains 22 parts gold and 2 parts of other metals added as alloy. ... 18 karat gold contains 18 parts pure gold with 6 parts of other metals added. In the West the karat is expressed in fineness.

Hence 22 carat gold is an alloy.

Multiple choice metals alloys and crystals chemistry elements and compounds alloys and their properties chemical bonding and structure

Which of the following properties of elements can be modified by the formation of alloys?

  1. Resistance to corrosion

  2. Toughness

  3. Malleability & ductility

  4. All of the above
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Alloys are used in some applications, where their properties are superior to those of the pure component elements, for a given application. This can include improvement in corrosion resistance (like stainless steel), toughness (like carbon-iron alloys) and malleability-ductility (like wrought iron).

Multiple choice chemistry elements and compounds alloys and their properties metals, alloys and crystals chemical bonding and structure

Which of the following methods can be used for the preparation of alloys?

  1. Melting a mixture of metals

  2. Simultaneous eletrolytic deposition of metals

  3. By mixing the aqeous solutions of the metal salts

  4. Both 1 and 2
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Alloys can either be produced by melting a mixture of metals or simultaneous eletrolytic deposition of metals. This is because alloys are interstitial compounds, and have one atom of a metal inside the solid structure of another atom. This requires mixing in an efficient way, and not just normal physical conditions. 

Multiple choice chemistry elements and compounds alloys and their properties metals, alloys and crystals chemical bonding and structure

Raney Nickel is finely divided nickel obtained by digesting alloys of $Ni/Al $ over $NaOH$.

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
Raney nickel is a fine-grained solid composed mostly of nickel derived from a nickel aluminum alloy
The alloy is treated with a concentrated solution of sodium hydroxide. The simplified leaching reaction is:
$2Al + 2NaOH + 6 H _2O \rightarrow  2 Na[Al{(OH)} _4] + 3 H _2$
After this process, leaching is done to form raney nickel which is powder and spongey.
Given statement is true.
Multiple choice chemistry elements and compounds alloys and their properties metals, alloys and crystals chemical bonding and structure

Consider the following statements:
(a) Mass is not affected by temperature and pressure.
(b) Plasma contains ionised gases.
(c) Alloys are homogenous mixtures.
(d) Solution is a heterogeneous mixture.
Which of the above statements are correct?

  1. (a), (b) and (c)

  2. (b) and (c)

  3. (a), (c) and (d)

  4. (a) and (d)
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

a. An increasing or decreasing temperature doesn't affect mass. Mass is the amount of matter in an object whereas temperature is the human sense of kinetic energy of matter. Thermal energy is very, very, very small, so no, it is not measurable as mass.

b. Plasma is the fourth state of matter. Plasma is an ionized gas, a gas into which sufficient energy is provided to free electrons from atoms or molecules and to allow both species, ions and electrons, to coexist.

c. An alloy is a homogeneous mixture of 2 or more metals or metal with 2 or more semi-metals.

d. It is homogeneous because the additions take place in the liquid state, so the atoms mingle with each other and mix thoroughly.

Multiple choice chemistry elements and compounds alloys and their properties metals, alloys and crystals chemical bonding and structure

An alloy is a material composed of two or more metals or a metal and a nonmetal. 

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

An alloy is a material composed of two or more metals or a metal and a nonmetal. An alloy may be a solid solution of the elements (a single phase), a mixture of metallic phases (two or more solutions) or an intermetallic compound with no distinct boundary between the phases. Solid solution alloys give a single solid phase microstructure, while partial solutions exhibit two or more phases that may or may not be homogeneous in distribution, depending on the thermal (heat treatment) history of the material. An inter-metallic compound has one other alloy or pure metal embedded within another pure metal.