Yes, it is a liquid because a solid is a state of matter with a fixed volume and shape; and Gases take both the shape and the volume of their container; and liquid is the one that takes the shape of their container but not necessarily the volume.
It’s c because a wave cycle is repeating patterns all over again and again
Oxygen is a liquid under one atmosphere. the boiling point of a substance is the temperature at which vapor pressure of a liquid is equal to the pressure of the surrounding liquid. the boiling point of oxygen at this case is 90.0k. Therefore the temperature of oxygen is 90-273= -183 celsius scale
Answer : The standard cell potential of the reaction is, -1.46 V
Explanation :
The given balanced cell reaction is,

Here, chromium (Cr) undergoes oxidation by loss of electrons and act as an anode. Lead (Pb) undergoes reduction by gain of electrons and thus act as cathode.
The standard values of cell potentials are:
Standard reduction potential of lead ![E^0_{[Pb^{2+}/Pb]}=-0.13V](https://tex.z-dn.net/?f=E%5E0_%7B%5BPb%5E%7B2%2B%7D%2FPb%5D%7D%3D-0.13V)
Standard reduction potential of chromium ![E^0_{[Cr^{3+}/Cr]}=1.33V](https://tex.z-dn.net/?f=E%5E0_%7B%5BCr%5E%7B3%2B%7D%2FCr%5D%7D%3D1.33V)
Now we have to calculate the standard cell potential for the following reaction.

![E^0=E^0_{[Pb^{2+}/Pb]}-E^0_{[Cr^{3+}/Cr]}](https://tex.z-dn.net/?f=E%5E0%3DE%5E0_%7B%5BPb%5E%7B2%2B%7D%2FPb%5D%7D-E%5E0_%7B%5BCr%5E%7B3%2B%7D%2FCr%5D%7D)

Therefore, the standard cell potential of the reaction is, -1.46 V