If the value of Avogadro number is 6.023 × 10²³ mol⁻¹ and the value of Boltzmann constant is 1.380 × 10⁻²³ JK⁻¹, then the number of significant digits in the calculated value of the universal gas constant is :

The relation between Boltzmann constant (k) and universal gas constant (R) is as follows:
k = R/NA
R = kNA = 1.380 × 10⁻²³ × 6.023 × 10²³ = 8.31174
In these operations, the result must be reported with no more significant figures as are there in the measurement with the few significant figures. Hence, the answer is 8.312, reported to 4 significant numbers as in the number with least significant numbers.
So, the number of significant figures in 8.312 is 4.
Hence, the correct option is A.