(a) What is the relationship between Celsius scale and Kelvin scale of temperature?
(b) Convert (i) ${\text{4}}{{\text{3}}^{\text{0}}}{\text{C}}$ into K, and (ii) ${\text{298 K}}$into${}^{\text{0}}{\text{C}}$.

Hint: Temperature is the measure of the hotness or coldness of an object with reference to some standard value. The average normal body temperature is ${\text{9}}{{\text{7}}^{\text{0}}}{\text{F}}$.
The relation between the Temperature in Celsius scale and in Kelvin scale is given by
\[{\text{T (}}{}^{\text{0}}{\text{C) = T (K) - 273}}\]. Now for conversion of Celsius into Kelvin or conversion of Kelvin into Celsius, use the same relation and substitute the given values in the relation. On further simplification, we can easily get the answer as the formula is very simple (not complex).

Complete step by step answer:
(a) The relation between the Celsius (represented by${}^{\text{0}}{\text{C}}$) and Kelvin (represented by K) is given by
\[{\text{T (}}{}^{\text{0}}{\text{C) = T (K) - 273}}...{\text{(I)}}\]
Where T represents temperature.
Thus, Celsius temperature is Kelvin temperature minus 273.

(b)
• Conversion of ${\text{4}}{{\text{3}}^{\text{0}}}{\text{C}}$ into K
Using relation${\text{(I)}}$, we have
\[{\text{T (K) = T (}}{}^{\text{0}}{\text{C)}}{\text{ + 273}}\]
Now, substituting the given value of temperature in${}^{\text{0}}{\text{C}}$, we get
\[
  {\text{T (K) = 43}}{}^{\text{0}}{\text{C + 273}} \\
  {\text{T = 316 K}} \\
 \]
Thus, on converting ${\text{4}}{{\text{3}}^{\text{0}}}{\text{C}}$ into K we get 316 K.

• Conversion of ${\text{298 K}}$into${}^{\text{0}}{\text{C}}$
Again using relation${\text{(I)}}$, we have
\[{\text{T (}}{}^{\text{0}}{\text{C) = T (K) - 273}}\]
On substituting value of 298 K, we have
\[
  {\text{T (}}{}^{\text{0}}{\text{C) = 298 - 273}} \\
  {\text{T = 15}}{}^{\text{0}}{\text{C}} \\ \]
Thus, on converting 298 K into${}^{\text{0}}{\text{C}}$, we get 15${}^{\text{0}}{\text{C}}$.

Note: Keep in mind that for positive value of temperature, Kelvin scale has larger value with respect to the Celsius scale. This is just a simple trick. This trick is obtained from the relation between the Celsius scale and Kelvin scale. As for obtaining temperature in Kelvin, 273 is added.
For negative values of temperature, the Kelvin scale may or may not have a smaller values with respect to the Celsius scale.