Draw a cooling graph of water as it passes from 20°c to –20°c. the y-axis should be temperature in degrees celsius and the x-axis should be time

Kindly, see the attached image.

Explanation:

As clear in the attached image:

It represents the cooling curve of water.It starts from 20°C, the water exists in the liquid phase.With time the temperature is decreased, reaching 0°C, the two phases (liquid and solid) are co-exist.Then, with further cooling and under 0°C reaching -20°C, all the water are exist in the solid phase (Ice).

Kindly, see the attached image that clarify the cooling graph of water as it passes from 20°C to –20°C.

(no3)⁻n has oxidation number x,o has oxidation number -2.(x*1 -2*3) charge of the nitrate ion, and we know that charge of the nitrate ion =-1.so,(x*1 -2*3) =-1x-6=-1x=+5answer a. +5.