(1) they contain free electrons Explanation: Metals typically consist of closepacked atoms, meaning that the atoms are arranged like closely packed spheres. Two packing motifs are common, one being bodycentered cubic wherein each metal atom is surrounded by eight equivalent atoms. The other main motif is face-centered cubic where the metal atoms are surrounded by six neighboring atoms. Several metals adopt both structures, depending on the temperature.

(1) they contain free electrons Explanation: Metals typically consist of closepacked atoms, meaning that the atoms are arranged like closely packed spheres. Two packing motifs are common, one being bodycentered cubic wherein each metal atom is surrounded by eight equivalent atoms. The other main motif is face-centered cubic where the metal atoms are surrounded by six neighboring atoms. Several metals adopt both structures, depending on the temperature.
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Helium gas is filled in ballons because (1) its atomic number is 2 (2) it is lighter than air (3) it is one of the constitutents of water (4) it is a noble gas
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How many neighboring atoms are in contact with eac atom in a monatomic body-centered cubic structure. w) 4 x) 6 y) 8 z) 12

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How many atoms per unit cell are in a face-centered-cubic crystal? w) two x) four y) six z) eight

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Out of the following, the lowest packing of atoms exists in __________ crystal lattice structure. (A) Hexagonal close, packed (hcp) (B) Face centred cubic (fcc) (C) Body centred cubic (bcc) (D) Simple cubic

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Metals are good conductors of electricity because (a) The contain free electrons (b) The atoms are lightly packed (c) They have high melting point (d) All of the above

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Metals are good conductors of electricity because - (1) they contain free electrons (2) the atoms are lightly packed (3) they have high melting point (4) All of the above

Description : Metals are good conductors of electricity because - (1) they contain free electrons (2) the atoms are lightly packed (3) they have high melting point (4) All of the above

Last Answer : (1) they contain free electrons Explanation: Copper is used for electrical wiring because it is a good conductor of electricity. Metal particles are held together by strong metallic bonds, which is why they have high melting and boiling points.

Metals are good conductors of electricity because – (1) they contain free electrons (2) the atoms are lightly packed (3) they have high melting point (4) All of the above

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Last Answer : (1) they contain free electrons Explanation: Copper is used for electrical wiring because it is a good conductor of electricity. Metal particles are held together by strong metallic bonds, which is why they have high melting and boiling points.

(3) reflection of light due to the presence of free electrons Explanation: Lustre (or luster) is the way light interacts with the surface of a crystal, rock, or mineral. The word traces its origins back to the latin lux, meaning "light", and generally implies radiance, gloss, or brilliance. Metals in general have high electrical conductivity, high thermal conductivity, and high density. Typically they are malleable and ductile, deforming -under stress without cleaving.

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How many neighboring atoms are in contact with each a in a hexagonal close-packed structure?

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The lustre of the metals is because of (1) high density, due to closed packing of atoms (2) high polish (3) reflection of light due to the presence of free electrons (4) absorption of light due to the presence of cavities

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If edge length of an unit cell `=4xx10^(-8)` cm and the unit cell is a face-centered cubic with atomic mass of metal is 40 then density of the unit ce

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(a) If the radius of the Br ion is 0.182 nm, how large a cation can fit in each of the tetrahedral hole. (b) AgI crystallizes in a cubic closed packed ZnS structure. What fraction of tetrahedral site is occupied by Ag ion ? (c) At what temp. range, most of the metals becomes super conductors ?

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Last Answer : (a) For a tetrahedron the limiting ratio is 0.225 – 0.414 For largest cation highest value 0.414 would be considered. r + / r– = 0.414 r + = 0.414 × 0.182 = 0.075 nm. (b) In FCC there are 8 tetrahedral voids. Out of this ½ is occupied by Ag cation. (c) 2 k – 5 k.

Metal spheres, each of radius 2 cm, are packed into a rectangular box of internal dimensions 16 cm x 8 cm x 8 cm. -Maths 9th

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Metal spheres, each of radius 2 cm, are packed into a rectangular box of internal dimensions 16 cm x 8 cm x 8 cm. -Maths 9th

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An epithelial tissue which has thin flat cells, arranged edge to edge so as to appear like closely packed tiles, is found to be present at (a) outer surface of ovary (b) inner lining of Fallopian tube (c) inner lining of stomach (d) inner lining of cheeks.

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Cubic crystals containing lattice points only at the corners are called: w) body centered x) face centered y) simple z) hexagonal

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(3) the number of electrons orbiting around the nucleus Explanation: The chemical behavior of an atom is determined by the number of electrons on its outer shell. As for the chemical bonding properties of the atom, the electron configuration determines how it will bond, with what it will bond, and in what ratio atoms will bond to form the 20,000,000 different substances on Earth.

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The number of octahedral void(s) per atom present in a cubic close-packed structure is (1) 4 (2) 1 (3) 3 (4) 2

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Closeness of packing is maximum in case of __________ crystal lattice. (A) Face centred (B) Simple cubic (C) Body centred (D) None of these

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Metal are good conductors, because (1) they contain free electrons (2) the molecules in them are very close to each other (3) the molecules in them collide very freely (4) they contain reflecting surface

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The size of the tetrahedral void in the closest packing of atoms is __________ that of the octahedral void. (A) Equal to (B) Greater than (C) Less than (D) Either (A), (B) or (C); depends on the size of atom

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Which of the following does the Nucleus of an atom consist of? (1) Protons and neutrons (2) Protons and electrons (3) Electrons (4) Protons

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For laminar flow of a fluid through a packed bed of spheres of diameter d, the pressure drop per unit length of bed depends upon the sphere diameter as (A) d (B) d 2 (C) d 4 (D) d

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The noble gases have low boiling points because: w) their ionization potentials are very low x) only weak Van der Waals forces hold the atoms together y) they are produced by the fractional distillation of liquid air z) they have eight electrons in the outer shell

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Which of the following crystal structures characterises the austenitic stainless steel? (A) Simple hexagonal (B) Body centred cubic (C) Face centred cubic (D) None of these

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Which of the following crystal structures characterises the ferritic stainless steel? (A) Face centred cubic (B) Body centred cubic (C) Simple hexagonal (D) None of these

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For a robot unit to be considered a functional industrial robot, typically, how many degrees of freedom would the robot have? a) three b) four c) six d) eight

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For a robot unit to be considered a functional industrial robot, typically, how many degrees of freedom would the robot have? A : Three B : Four C : Six D : Eight

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For a robot unit to be considered a functional industrial robot, typically, how many degrees of freedom would the robot have? A : Three B : Four C : Six D : Eight

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Resonance structures of a molecule have (a) same arrangement of atoms (b) different arrangement of atoms (c) same number of paired electrons (d) different number of paired electrons

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Mark correct option a) Sorting sub office are situated near the junction of several mail linesb) Nodal Post office is working in important cities some post office are authorized to receive letters from neighboring PO and sort the mail as per sorting diagram.c) Central bagging unit is branch of RMS office .d) All the above

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What does a “curved” arrow represent? (a) that two structures are resonance structures (b) the movement of two electrons (c) a link between reactants and products (d) that two structures are equivalent

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Which of these columns incurs the lowest pressure drop? (A) Packed column (with stacked packing) (B) Packed column (with dumped packing) (C) Bubble plate column (D) Pulse column

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In a moderately sized packed absorption tower, channelling (which is most severe with stacked packings) can be minimised by taking the ratio of tower diameter to packing diameter (A) > 4 :1 (B) < 8 : 1 (C) > 8:1 (D) < 6:1

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Last Answer : (C) > 8:1

Channelling is most severe (A) In towers packed with stacked packing (B) In towers packed randomly with crushed solids (C) In dumped packing of regular units

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Pressure drop through plate tower as compared to that through packed tower, for the same duty will be (A) Less (B) More (C) Equal (D) Either (A) or (B); depends on the packing height

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(2) experience collision less frequently Explanation: When an electric field is applied, both the valence electrons and the free electrons move in the same direction. The hole direction is opposite to that of valence electron but the mobility is the same. Even for the same electric field, valence electrons cannot move as freely as the free electrons because its movement is restricted due to collisions. Therefore, the velocity of valence electrons is less compared to free electrons. In other words, the velocity of holes is less compared to free electrons. This means mobility is also less for a hole compared to free electron.

Description : (2) experience collision less frequently Explanation: When an electric field is applied, both the valence electrons and the free electrons move in the same direction. The hole direction is opposite to that ... to free electrons. This means mobility is also less for a hole compared to free electron.

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Cinnabar, pyrite and galena are minerals which consist of one or more metals combined with the same element. Which one of the following is the element that is common to all three of these minerals? Is it: w) iron x) copper y) sulfur z) sodium

Description : Cinnabar, pyrite and galena are minerals which consist of one or more metals combined with the same element. Which one of the following is the element that is common to all three of these minerals? Is it: w) iron x) copper y) sulfur z) sodium

Last Answer : ANSWER: C-- SULFUR

Each myoglobin molecule contains (A) One iron atom (B) Two iron atoms (C) Four iron atoms (D) Six iron atoms

Description : Each myoglobin molecule contains (A) One iron atom (B) Two iron atoms (C) Four iron atoms (D) Six iron atoms

Last Answer : Answer : A

Each haemoglobin molecule contains (A) One iron atom (B) Two iron atoms (C) Four iron atoms (D) Six iron atoms

Description : Each haemoglobin molecule contains (A) One iron atom (B) Two iron atoms (C) Four iron atoms (D) Six iron atoms

Last Answer : Answer : C

Which of the following is not characteristic of resonance? (a) The canonical structures have the constituent atoms in the same relative positions (b) They have nearly the same energy (c) They have the same number of unpaired electrons (d) The actual structure can be represented on paper using the conventional symbols

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Metals, in general are of low strength and do not possess required physio-chemical and technological properties for a definite purpose. Alloys are therefore more than metals alone. Discuss the arrangement of atoms and Structures of alloys.

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