The sharp melting point of crystalline solids is due to ___________.
(A) a regular arrangement of constituent particles observed over a short distance in the crystal lattice.
(B) a regular arrangement of constituent particles observed over a long distance in the crystal lattice.
(C) same arrangement of constituent particles in different directions.
(D) different arrangements of constituent particles in different directions.
(A) a regular arrangement of constituent particles observed over a short distance in the crystal lattice.
(B) a regular arrangement of constituent particles observed over a long distance in the crystal lattice.
(C) same arrangement of constituent particles in different directions.
(D) different arrangements of constituent particles in different directions.
(B) a regular arrangement of constituent particles observed over a long distance in the crystal lattice.
Which of the following statements is not true about amorphous solids?
(A) On heating they may become crystalline at certain temperature.
(B) They may become crystalline on keeping for long time.
(C) Amorphous solids can be moulded by heating.
(D) They are anisotropic in nature.
Which of the following statements is not true about the hexagonal close packing?
(A) The coordination number is 12.
(B) It has 74% packing efficiency.
(C) Tetrahedral voids of the second layer are covered by the spheres of the third layer.
(D) In this arrangement spheres of the fourth layer are exactly aligned with those of the first layer.
Which of the following is true about the value of refractive index of quartz glass?
(A) Same in all directions
(B) Different in different directions
(C) Cannot be measured
(D) Always zero
Interstitial compounds are formed when small atoms are dropped under the curved lattice of metals. Which of the following is not the characteristics property of interstitial compounds?
(A) They have high melting points in to pure metals
(B) They are very hard
(C) They retain metallic Conductivity
(D) They are chemically very reactive
Which of the following is not true about the ionic solids?
(A) Bigger ions form the close packed structure.
(B) Smaller ions occupy either the tetrahedral or the octahedral voids depending upon their size.
(C) Occupation of all the voids is not necessary.
(D) The fraction of octahedral or tetrahedral voids occupied depends upon the radii of the ions occupying the voids.
Which of the following conditions favours the existence of a substance in the solid state?
(A) High temperature
(B) Low temperature
(C) High thermal energy
(D) Weak cohesive forces
Solid A is very hard electrical insulator in solid as well as in molten state and melts at an extremely high temperature. What type of solid is it?
(A) Ionic solid
(B) Molecular solid
(C) Covalent solid
(D) Metallic solid
The magnetic moment is associated with its spin angular momentum and orbital angular momentum. Spin only magnetic moment value of Cr³⁺ ion is
(a) 2.87 BM
(b) 3.87 BM
(c) 3.47 BM
(d) 3.57 BM
Stability of hydrides of group 16 elements
a) increases down the group
b) decreases down the group
c) all hydrides are equally stable
d) none of the above
Which of the following will have the maximum dipolemoment?
(a) \(CH_3\)F.
(b) \(CH_3\)Cl.
(c) \(CH_3\)Br.
(d) \(CH_3\)I.
Assertion: The two strands of DNA are complementary to each other.
Reason: The hydrogen bonds are formed between specific pairs of bases.
A. Assertion and reason both are correct statements and reason is correct explanation for assertion.
B. Assertion and reason both are correct statements but reason is not correct explanation for assertion.
C. Assertion is correct statement but reason is wrong statement.
D. Assertion is wrong statement but reason is correct statement.
Identify the correct order of acidic strength for H-X
a) HCl > HBr > HI.
b) HCl > HI > HBr.
c) HI > HCl > HBr.
d) HI > HBr > HCl.
How is electrical conductance of a conductor related with length and area of cross-section of the conductor?
a. G = \(l. a.k^{-1}\)
b. G = \(k. l.a^{-1}\)
c. G = \(k.a. l^{-1}\)
d. G = \(k. l.a^{-2}\)
What is the coordination number in a square close packed structure in two dimensions?
(A) 2
(B) 3
(C) 4
(D) 6