Answer A
x-ray optical telescope.
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Arrangement of atoms or group of atoms in a three dimensional ordered pattern in a crystal is said to be a crystalline lattice. They are arranged in a specific pattern with high symmetry. The heating of the crystal at high temperature will result in the increase of vibrational kinetic energy of the atoms in the crystal and this will result in the breaking of lattice apart and due to the breaking of lattice apart the ions will flow freely.
Thus, the heating of a solid at high temperature will lead to the lattice breaks apart and ions will flow freely.
69. The student's skin was obviously warmer than the initial temperature of the bracelet. According to the second law of thermodynamics, heat transfers from a higher temperature to a lower temperature hence heat transfers from the student's skin to the bracelet warming up the bracelet.
70. moles of copper=mass of copper/molar mass of copper
=30.1g/(63.55g/mol)= 0.4736 moles Cu
71. Delta H( heat released) = mCp(deltaT) = 30.1g(0.385 J/gK)(33-19)K = 162.23J
72. Copper is chemically less active than iron.