Doubtly
@Doubtly · Joined Feb 2021
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- The astrologer has changed his appearance and his persona when he arrived in the city. Give specific reasons. When astrologer was a silly youngster, he quarreled with Guru Nayak and tried to kill him in wrath. He thought that he had murdered Guru Nay... 1
- English model paper std 12th board exam SECTION I – PROSE (Reading for Comprehension, Language Study, Summary, Mind Mapping) Q.1 A) Read the extract and complete the activities giv... 2
- “55% of messages received and processed by the brain are based on your body language.” Kinesics is the interpretation of body motion communication such as facial expressions and gestures, nonverbal behavior related to movement... 1
- An element with molar mass 27 g/mol forms cubic unit cell with edge length of 405 pm Given : Molar mass = M= 27 g m0l_‘ Nature of crystal = cubic unit cell Edge length = a = 405 pm = 4.05 x 10⁻⁸ cm Density = ρ = 2.7 g cm⁻³ Na... 1
- An element has a bcc structure with unit cell edge length of 288 pm. Given: Types of unit cell = bcc, for bcc unit cell n = 2 Edge length (a) = 288 pm = 2.88 x 10^(-8 )cm³ Mass of element (x) =200g Density of... 1
- In an ionic crystalline solid atoms of element Y form hcp lattice. In the given hcp lattice, Y atoms are present at 12 corners and 2 face centres. ∴ Number of Y atoms = 1/6×12 +1/2×2 = 2+1= 3 There are 6 tet... 2
- Aluminium crystallizes in cubic close packed structure with unit cell edge length of 353.6 pm. Given : Structure of Al = Cubic close packed structure = ccp structure Edge length of unit cell = a = 353.6 pm = 3.536 x 10⁻⁸ cm r = ? Numbe... 1
- The density of iridium is 22.4 g/cm3. The unit cell of iridium is fcc. Calculate the radius of iridium atom. Given : Crystal structure of iridium = fcc Molar mass of iridium = 192.2 gmol⁻¹ Density = ρ = 22.4 gcm⁻³ Radius of iridium = ? In fcc struct... 1
- Obtain the relationship between density of a substance and the edge length of unit cell. Consider edge length of cubic unit cell is a, the ∴ Volume of unit cell = a³. Suppose that mass of one particle is m and that there are n pa... 1
- Cu crystallizes in fcc unit cell with edge length of 495 pm. Given : a = 495 pm Radius, r = ? For fcc structure, Radius = r = a/2√(2)= 495/2√(2) = 175pm Ans. Radius of Cu atom = 175 pm. 1
- Cesium chloride crystallizes in cubic unit cell with Cl- ions at the corners and a Cs+ ion in the centre of the cube. Number of Cs⁺ ion at body centre = 1 A Number of Cl⁻ ions due to 8 comers = 1/8×8 = 1 Hence unit cell contains 1 CsCl molecule. 1
- What are the consequences of Schottky defect? Consequences of Schottky defect : As the number of ions decreases, mass decreases. However, volume remains unchanged. Hence, the density of... 1
- What are paramagnetic substances? Give examples. Paramagnetic substances : The magnetic properties of a substance arise due to the presence of electrons. An electron while revolving around... 1
- Calculate the packing efficiency of metal crystal that has simple cubic structure. Packing efficiency of metal crystal in simple cubic lattice : Step 1 : Radius of sphere : In simple cubic unit cell, particles (spheres) are... 1
- How are the spheres arranged in first layer of simple cubic close-packed structures? How are the successive Three dimensional crystal structures are obtained by stacking of two dimensional layers. Simple cubic lattice is obtained by stacking of two... 1
- Calculate the number of atoms in fcc unit cell. Number of atoms in face-centred cubic (fcc) unit cell : In this unit cell, there are 8 atoms at 8 corners and 6 atoms at 6 face centres. Eac... 1
- Distinguish between ionic solids and molecular solids. Ionic solids are made of oppositely charged ions held by strong electrostatic forces, while molecular solids are made of molecules held by w... 1
- What are valence band and conduction band? Valence band : The atomic orbitals with filled electrons from the inner shells form valence bands, where there are no free mobile electrons s... 1