Defects in solids

37 questions on Defects in solids from the Solid State chapter: 7 NEET level, 14 JEE Main, 16 JEE Advanced. Each one opens with its answer and solution.

• Which effect does a Schottky defect have on the density of an ionic crystal? NEET level
• Which of the following defects does not change the density of the crystal? NEET level
• The colour of NaCl heated in sodium vapour is due to NEET level
• Zinc oxide turns yellow on heating and regains its white colour on cooling. This is because JEE Main level
• Perfect NaCl has density 2.165 g cm^-3. If 0.5% of the Na+ and Cl- sites are vacant in equal numbers (Schottky defects) with no change in cell volume, the densi... JEE Main level
• Which of the following gives an n-type semiconductor? JEE Main level
• Which solid among the following can show both Schottky and Frenkel defects? JEE Main level
• NaCl is doped with SrCl2 at 1.2x10^-2 mol%. Each Sr^2+ replaces two Na+ ions' worth of charge by creating one cationic vacancy. Using N_A=6.022x10^23 mol^-1, fi... JEE Main level
• A sample of 5.85 g of NaCl (M=58.5 g mol^-1) has a fraction 2.5x10^-8 of its cation sites vacant because of Schottky defects. Using N_A=6.022x10^23 mol^-1, find... JEE Main level
• Which statements about point defects in ionic solids are correct? JEE Main level
• A sample of wustite has the composition Fe_0.92O. Assuming only Fe^2+ and Fe^3+ are present, the percentage of iron present as Fe^3+ is JEE Advanced level
• Assertion (A): A Frenkel defect does not alter the density of an ionic crystal. Reason (R): In a Frenkel defect the displaced cation moves to an interstitial si... JEE Advanced level
• Silicon (M=28 g mol^-1, density 2.33 g cm^-3) is doped with phosphorus at 1 atom per 10^7 Si atoms. Assuming each P atom donates one free electron and N_A=6.022... JEE Advanced level
• A sample of iron(II) oxide has the formula Fe_0.94O with only Fe^2+ and Fe^3+ ions. Find the percentage of iron present as Fe^3+ (nearest integer). JEE Advanced level
• Wustite Fe_0.95O has the rock-salt structure with edge length 430 pm (4 formula units per cell). Atomic masses: Fe =56, O =16; N_A=6.022x10^23 mol^-1. Calculate... JEE Advanced level
• A NaCl crystal of volume 1.00 mm^3 (edge of unit cell 564 pm, 4 anion sites per cell) has 1 in 10^6 of its anion sites occupied by F-centres. Find the number of... JEE Advanced level
• NaCl is doped with a small amount of SrCl2. Which statements are correct? JEE Advanced level
• For the non-stoichiometric oxide Fe_0.95O, which statements are correct? JEE Advanced level
• Which statements about F-centres in alkali halides are correct? JEE Advanced level
• The effect of Schottky defects on the density of an ionic crystal is that the density NEET level
• Which of the following crystals is expected to show Frenkel defects? NEET level
• An F-centre in an alkali halide crystal is NEET level
• Fe_0.95O is an example of NEET level
• When white ZnO is heated it turns yellow and on cooling becomes white again. The yellow colour is due to JEE Main level
• Assertion (A): Frenkel defects do not change the density of an ionic crystal. Reason (R): In a Frenkel defect an ion is only displaced to an interstitial site, ... JEE Main level
• A crystal containing 11.7 g of NaCl (molar mass 58.5 g mol^-1) has one Schottky pair for every 10^6 formula units. Taking N_A = 6.022x10^23 mol^-1, find the num... JEE Main level
• A sample of ferrous oxide has the composition Fe_0.93O. Assuming only Fe^2+ and Fe^3+ are present, calculate the percentage of the iron present as Fe^3+ (neares... JEE Main level
• An ideal NaCl crystal has density 2.165 g cm^-3. In a real crystal 0.50% of the formula units have a Schottky pair missing, with no change in cell volume. Find ... JEE Main level
• Which of the following statements about point defects are correct? JEE Main level
• A crystal of NaCl is doped with a small amount of SrCl2. Which statements are correct? JEE Main level
• The edge of the NaCl unit cell is 564 pm (molar mass 58.5 g mol^-1, N_A = 6.022x10^23 mol^-1). The measured density of a crystal sample is 2.155 g cm^-3. If the... JEE Advanced level
• NaCl of density 2.165 g cm^-3 is doped with SrCl2 so that 2.0x10^-3 mol % of the cations are Sr^2+ (i.e. Sr^2+ is a mole fraction of 2.0x10^-5 of the cations). ... JEE Advanced level
• A sample of nickel oxide has the formula Ni_0.97O with nickel present only as Ni^2+ and Ni^3+. The ratio Ni^3+ : Ni^2+ in the sample is closest to JEE Advanced level
• A crystal has Schottky defects in 1.0% of its formula units (each such unit has lost one cation and one anion) and, in addition, Frenkel defects in 2.0% of the ... JEE Advanced level
• Which of the following statements are correct? JEE Advanced level
• A crystal of AgCl shows Frenkel defects. Which statements are correct? JEE Advanced level
• One mole of AgCl is doped with 2.0x10^-4 mol of CdCl2, each Cd^2+ replacing an Ag+ ion. With N_A = 6.022x10^23 mol^-1, the number of cation vacancies created is JEE Advanced level