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Given below are two statements:
Statement I : Frenkel defects are vacancy as well as interstitial defects.
Statement II : Frenkel defect leads to colour in ionic solids due to presence of F-centres.
Choose the most appropriate answer for the statements from the options given below:

A hard substance melts at high temperature and is an insulator in both solid and in molten state. This solid is most likely to be a/an:

In a binary compound, atoms of element A form a hcp structure and those of element M occupy \( \frac{2}{3} \) of the tetrahedral voids of the hcp structure. The formula of the binary compound is:

Select the correct statements.
A. Crystalline solids have long range order.
B. Crystalline solids are istropic.
C. Amorphous solids are sometimes called pseudo solids.
D. Amorphous solids soften over a range of temperatures.
E. Amorphous solids have a definite heat of fusion.
Choose the most appropriate answer from the options given below :

A copper complex crystallising in a CCP lattice with a cell edge of \( 0.4518 \, \text{nm} \) has been revealed employing X-ray diffraction studies. The density of a copper complex is found to be \( 7.62 \, \text{g cm}^{-3} \). The molar mass of copper complex is ______ \( \text{g mol}^{-1} \). (Nearest integer)
[Given: \( N_a = 6.022 \times 10^{23} \, \text{mol}^{-1} \)]

Given below are two statements. One is labeled as Assertion A and the other is labelled as Reason R.
Assertion A: Sharp glass edge becomes smooth on heating it upto its melting point.
Reason R: The viscosity of glass decrease on melting.
Choose the most appropriate answer from the options given below.

Match items of List-I with those of List-II:

Choose the most appropriate answer from the options given below:

The empirical formula for a compound with a cubic close packed arrangement of anions and with cations occupying all the octahedral sites in \( \mathrm{A}_x\mathrm{B}_{} \). The value of \( x \) is _______. (Integer answer)

The oxide that shows magnetic property is:

Diamond has a three dimensional structure of \( \text{C} \) atoms formed by covalent bonds. The structure of diamond has face centred cubic lattice where \( 50\% \) of the tetrahedral voids are also occupied by carbon atoms. The number of carbon atoms present per unit cell of diamond is ________ .

Ga (atomic mass \( 70 \, \text{u} \)) crystallizes in a hexagonal close packed structure. The total number of voids in \( 0.581 \, \text{g} \) of Ga is __________ \( \times 10^{21} \). (Round off to the Nearest Integer).

KBr is doped with \( 10^{-5} \) mole percent of \( \mathrm{SrBr}_2 \). The number of cationic vacancies in \( 1 \ \text{g} \) of KBr crystal is ________ \( \times 10^{14} \). (Round off to the Nearest Integer) [Atomic Mass: \( \mathrm{K}: 39.1\,\text{u} \), \( \mathrm{Br}: 79.9\,\text{u} \), \( N_A = 6.023\times 10^{23} \)]

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JEE Main 2021 16th March Evening Shift

Ga (atomic mass \( 70 \, \text{u} \)) crystallizes in a hexagonal close packed structure. The total number of voids in \( 0.581 \, \text{g} \) of Ga is __________ \( \times 10^{21} \). (Round off to the Nearest Integer).