Crystal System and Bravais Lattice

Q. In a face centered lattice of X and Y, X atoms are present at the corners while Y atoms are at face centers. What would be the simplest formula of the compound if one of the X atoms is missing from a corner in each unit cell?

1. $X_7{Y}_{24}$
2. $X_{24}{Y}_{24}$
3. $X{Y}_{24}$
4. $X_{24}{Y}_7$

Q. '$C$' represent the height of the HCP unit cell and '$a$' represent edge length of the hexagonal surface of the HCP unit cell. What is the value of $\frac{C}{a}$?

1. $\sqrt{\frac{2}{3}}$
2. $\sqrt{\frac{8}{3}}$
3. $\sqrt{\frac{32}{3}}$
4. $\sqrt{\frac{3}{2}}$

Q.

Why dont crystals have 5 fold symmetry?

Q. The molar volume of KCl and NaCl are 37.46 ml and 27.94 ml. The ratio of unit cell edges of the two crystals is :

1. 1.296
2. 1.116
3. 1.341
4. 0.950

Q. If all the three inter-axial angles defining the unit cell are equal in magnitude, the crystal cannot belong to the ______ system.

1. Orthorhombic
2. Hexagonal
   
3. Tetragonal
4. Cubic

Q. How many space lattices are obtainable from the different crystal systems

1. 7
2. 14
3. 32
4. 230

Q. The most unsymmetrical crystal system is:

1. Cubic
2. Hexagonal
3. Triclinic
4. Orthorhombic

Q.

Total number of Bravais Lattices are

1. 7

2. 10

3. 14

4. 16

Q. Molybdenum ($\text{Atomic wt.}=96g/mol$) crystallizes as bcc crystal. If density of crystal is $10.3g/c{m}^3,$ what will be the radius of $Mo$ atom? $[\text{U}se:N_A=6\times {10}^{23}]$

1. $111pm$
2. $314pm$
3. $136pm$
4. $152pm$

Q. A given element A has a face centred unit cell in which A is absent from two of the corners.
The packing fraction is :

1. $\frac{7\pi }{2\sqrt{2}}$
2. $\frac{5\pi }{16\sqrt{2}}$
3. $\frac{5\pi }{8\sqrt{2}}$
4. $\frac{7\pi }{4\sqrt{2}}$

Q.

In simple cubic unit cell distance between first and fourth layer :-(1) 4 r(2) 2 r(3) 6 r(4) None of these

Q. If $a,b,c$ represent cell dimensions and $\alpha ,\beta ,\gamma$ represents crystal angles then, the crystal system $a\ne b\ne c,\alpha =\gamma ={90}^{\circ },\beta \ne {90}^{\circ }$ belongs to:

1. Tetragonal
2. Triclinic
3. Hexagonal
4. Monoclinic

Q. An element of density $7gc{m}^{-3}$ occurs in bcc structure with cell edge of $300pm$. Calculate the number of atoms present in $200g$ of the element.

1. $$2.4\times {10}^{42}$$
2. $$1.2\times {10}^{42}$$
3. $$1.2\times {10}^{24}$$
4. $$2.1\times {10}^{24}$$

Q. Match the following crystal system with their axial angles.

1. $\alpha =\beta =\gamma =90°$
2. $\alpha =\beta =\gamma \ne 90°$
3. $\alpha =\gamma =90°\beta \ne 90°$
4. $\alpha \ne \beta \ne \gamma \ne 90°$

Q. Lithium borohydride $\left(LiB{H}_4\right)$, crystallizes in an orthorhombic system with $4$ molecules per unit cell. The unit cell dimensions are $a=6.22\stackrel{\circ }{\text{A}}$, $b=5\stackrel{\circ }{\text{A}}$, $c=7\stackrel{\circ }{\text{A}}$. If the molar mass of $LiB{H}_4$ is $21.76{\text{g mol}}^{-1}$. The density of the crystal is:
$(N_A=6\times {10}^{23})$

1. $0.666{\text{g cm}}^{-3}$
   
2. $0.585{\text{g cm}}^{-3}$
   
3. $1.23{\text{g cm}}^{-3}$
   
4. None of these

Q. 1 mole of a gas occupying 3 litres volume is expanded against a constant external pressure of 1 atmosphere to a volume of 15 litre calculate the work done by the system

Q. When ZnO lattice is heated, the formula of lattice becomes (x > 0) : (1) ZnO (2) Zn(1+x)O (3) ZnO(1+x) (4) Zn(1-x)O

Q. Lithium has a $bcc$ structure. Its density is $530{\text{kg m}}^{-3}$ and its atomic mass is $6.94{\text{g mol}}^{-1}$. Calculate the edge length of a unit cell of lithium metal. $(N_A=6.02\times {10}^{23}{\text{mol}}^{-1})$

1. $527\text{pm}$
2. $264\text{pm}$
3. $154\text{pm}$
4. $352\text{pm}$

Q. Which crystal system of the unit cell has dimensions as : $a\ne b\ne c\text{and}\alpha \ne \beta \ne \gamma \ne {90}^o$?

1. Monoclinic
2. Triclinic
3. Orthorhombic
4. Rhombohedral

Q. In a hexagonal close packing, the edge length of base of a unit cell is $100pm$. Find the volume of the hcp unit cell if the height of the cell is $160pm$.

1. $416\times {10}^{-26}c{m}^3$
2. $286\times {10}^{-26}c{m}^3$
3. $543\times {10}^{-26}c{m}^3$
4. $750\times {10}^{-26}c{m}^3$

Q. Which has no rotation of symmetry

1. orthorhombic
2. cubic
3. Triclinic
4. Hexagonal

Q. 250 ml of N maintained at 720 mm pressure and 380 ml of oxygen maintained at 650mm pressure are put together in one litre flask. Is the temperature is kept constant what will be there final pressure of the mixture.

Q. Assuming all spheres have equal radii and are close packed in two dimension. The correct relation between the packing fractions of the structure given below is

1. $n_1=n_2=n_3$
2. $n_1>n_2>n_3$
3. $n_2>n_3>n_1$
4. $n_1>n_3>n_2$

Q. Crystals can be classified into....... basic crystal systems.

1. 7
2. 4
3. 14
4. 3

Q. Percentage by volume of C3H8 in a gaseous mixture of C3H8, CH4, CO is 20.When 100 ml of mixture is burnt in excess of oxygen .The volume of CO2 produced at STP will be 1.90 ml 2.160 ml 3.140 ml 4.200 ml

Q. Iron occurs as bcc as well as fcc unit cell. If the effective radius of an atom of iron is $100pm$, then choose the correct option regarding densities of unit cell :
Take $\sqrt{\frac{2}{3}}\approx 0.82$

1. ${\rho }_{fcc}>{\rho }_{bcc}$
2. ${\rho }_{bcc}>{\rho }_{fcc}$
3. ${\rho }_{fcc}={\rho }_{bcc}$
4. Cannot be predicted

Q.

A matchbox is an example of :-

1. Cubic

2. Orthorhombic

3. Monoclinic

4. Rhombohedral

Q. 37.At what temperature 25dm of oxygen at 283k is heated to make its volume 30 dm

Q. CaCO3 BELONGS TO WHICH CRYSTAL SYSTEM , rhombhohedral or orthorhombhic?

Q. In a hexagonal close packing, the edge length of base of a unit cell is $100pm$. Find the volume of the hcp unit cell if the height of the cell is $160pm$.

1. $416\times {10}^{-26}c{m}^3$
2. $286\times {10}^{-26}c{m}^3$
3. $543\times {10}^{-26}c{m}^3$
4. $750\times {10}^{-26}c{m}^3$