Chemistry · Some Basic Concepts Of Chemistry · NEET
NCERT Class 11 Chemistry (Some Basic Concepts of Chemistry) gives: °F = (9/5)(°C) + 32. You put the Celsius value in place of °C, multiply by 9/5, and then add 32. This is the only formula NEET expects.
Use 9/5 (which equals 1.8) when going Celsius to Fahrenheit. You use 5/9 only for the reverse direction (Fahrenheit to Celsius). Simple check: Fahrenheit numbers are larger, so you multiply by the bigger fraction 9/5. If you got a smaller answer, you used the wrong fraction.
The two scales do not start at the same point. Water freezes at 0 °C but at 32 °F. So even at 0 °C, Fahrenheit already reads 32. The +32 shifts the answer up so both scales agree at the freezing point of water.
Multiply first, then add. Order of operations: (9/5)(°C) is done before adding 32. Example for 40 °C: first 40 × 9/5 = 72, then 72 + 32 = 104 °F. If you add 32 first you get the wrong answer.
0 °C = (9/5)(0) + 32 = 32 °F (freezing point of water). 100 °C = (9/5)(100) + 32 = 180 + 32 = 212 °F (boiling point of water). So the Celsius scale runs 0 to 100 while Fahrenheit runs 32 to 212 for the same range.
Rearrange the same formula: °C = (5/9)(°F − 32). First subtract 32, then multiply by 5/9. It is the exact reverse of Celsius to Fahrenheit, so learn one formula well and you can flip it.
Try the real previous-year questions from this chapter — each with the answer and a full solution.
°F = (9/5)(°C) + 32. Multiply the Celsius value by 9/5 (1.8) and then add 32.
37 °C = (9/5)(37) + 32 = 66.6 + 32 = 98.6 °F, which is normal human body temperature.
Kelvin (K) is the SI unit of temperature. Fahrenheit and Celsius are common scales but not SI. NCERT relates them by °F = (9/5)(°C) + 32 and K = °C + 273.15.
Between freezing and boiling, Celsius covers 100 degrees (0 to 100) while Fahrenheit covers 180 degrees (32 to 212). The ratio 180/100 = 9/5, so each Celsius degree equals 9/5 of a Fahrenheit degree.
