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Arizona State University consistently ranks highly in a number of National and Global University rankings. In the 2025 National Universities ranking, this university ranks at #121 in 2025, according to a top-ranking publisher. According to a top-world ranking publisher, Arizona State University ranking is #200. A few other prominent rankings for this university are:

• ASU ranks at #2 in the U.S. for employability among public universities as per Global Employability University Ranking and Survey 2025
• This university ranks in the Top 1% of international university ranking list as per the 2024 edition of the Global 2000 list by the Center for World University Rankings
• ASU ranks among the Top 15 on the Best Colleges for Futures Leaders list among the public universities, according to TIME 2025

1.31 (i) In hexagonal close packing (hcp), the spheres of the third layer are vertically above the spheres of the first layer. It means tetrahedral voids of the second layer are covered by the spheres of the third layer. The AB. type.In cubic close packing (ccp), the spheres of third layer cover the octahedral voids of second layer. But the spheres of the fourth layers are aligned with those of the first layer. The pattern is ABC. type.

(ii) Crystal lattice is the three dimensional arrangement of identical point in the space which represent how the constituent particles (atoms, ions, molecules) are arranged in a crystal.Unit cell is the smallest portion of a crystal lattice which, when repeated in different directions, generates the entire lattice

(iii) Tetrahedral voids are surrounded by four spheres which lie at the vertices of a regular tetrahedron. There are 2 tetrahedral voids per atom in a crystal.
Octahedral voids are surrounded by six spheres and formed by a combination of two triangular voids of the first and second layer. There is one octahedral void per atom in a crystal.

1.30 Stability of a crystal is directly proportional to the magnitude of its melting points. Higher is the magnitude of forces holding the constituent particles together, higher will be the melting point and higher will be the stability. Thus ionic crystals (NaCl, KNO3 etc.) have very high melting points and stable crystal lattices. On other hand, molecular solids (naphthalene, iodine etc.) have low melting points and low stability.

The melting points of solid water, ethyl alcohol, diethyl ether and methane are 273 K, 155.8 K, 156.8 K and 90.5 K respectively.Solid water and ethyl alcohol have higher melting points due to presence of inter-molecular hydrogen bonds. Since the extent of hydrogen bonding in solid water is greater than the extent of hydrogen bonding in ethyl alcohol, the melting point of solid water is higher than the melting point of ethyl alcohol. 
Polar diethyl ether involves dipole-dipole interactions. Non polar methane involves weak van there Waals forces (London dispersion forces) which are weaker than dipole-dipole interactions. Hence, the melting point of methane is much lower than the melting point of diethyl ether.

Green chemistry is a way of thinking and is about utilising the existing knowledge and principles of chemistry and other sciences to reduce the adverse effect of pollution. It is a production process that would bring about minimum pollution or deterioration to the environment. In a nutshell, it is a cost-effective approach which involves reduction in material, energy consumption and waste generation.
It will help in decreasing environmental pollution by adopting the following examples:

1. In a chemical reaction, if reactants are fully converted into useful environmental friendly products by using an environment friendly medium then there would be no chemical pollutants introduced in the environment.
2. During a synthesis, care must be taken to choose starting materials that can be converted into end products with yield approximately up to 100 per cent.
3. It may be worthwhile to carry out synthetic reactions in aqueous medium since water has high specific heat and low volatility. Water is cost effective, non inflammable and devoid of any carcinogenic effects.