Hydrogen bonding is important because it is crucial to all life on Earth. Here are three reasons why hydrogen bonding is important. DNA has a double-helix structure because hydrogen bonds hold together the base pairs in the middle. Without hydrogen bonds, DNA would have to exist as a different structure.
Answer:
A chemical change is a change in the chemical makeup of a substance and results in a new substance. Ice and water both have the same chemical makeup - ice is just a different state and has the same atoms but in an expanded form.
Explanation:
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.
Answer:
Option-1 (O²⁻) is the correct answer.
Explanation:
All given anions contains same charge. So, we can ignore the effect of charge on these anions.
As we know all given compounds belongs to same group (Group 6) in periodic table. And from top to bottom along the group the elements are placed as,
Oxygen O
Sulfur S
Selenium Se
Tellurium Te
Hence, moving from top to bottom along the group the number of shells increases. And with increase in number of shell the atomic or ionic radii increases. As Oxygen is present at the top of the group, therefore, it has the smallest radius due to less number of shells.
