I believe the answer is D
Ionic crystals are hard because of tight packing lattices, say, the positive and negative ions are strongly attached among themselves.
Answer:
The temperature at which rhenium becomes superconducting is -271.6 ºC.
Explanation:
We can convert the temperature given in Kelvin, which is an absolute scale, into degrees Celsius. which is a relative scale, by a simple algebraic translation, that is:
(1)
Where:
- Temperature, measured in degrees Celsius.
- Temperature, measured in Kelvins.
If we know that 
, then the temperature given in degrees Celsius is:
The temperature at which rhenium becomes superconducting is -271.6 ºC.
Answer: Water H2O
Explanation:
In cellular respiration process NAD+ is a most versatile electron acceptor and functions in several of the redox steps during break down of glucose.
Each NADH molecules formed during respiration represents stored energy that can be tapped to make ATP when the electrons complete their ''fall''down an energy gradient from NADH to oxygen.
Electrons removed from glucose are shuttle by NADH to the ''top'', higher-energy end of the electron transport chain. At the ''bottom'' lower energy end, O2 captures these electrons along with H+ forming water.
Therefore Hydrogen removed from NADH in the ETC is captured by O2 to form water
2H + 1/2O2 ------> H20
According to the kinetic theory of gases, the collisions among the molecules are perfectly elastic, that is, when the collision of the molecules takes place, they bounce off each other with no gain or loss of energy. No repulsive or attractive forces take part at the time of collisions, so energy is conserved.
