If the value of Avogadro numberis `6.023xx10^(23)mol^(-1)` and the vaueof Boltzmann constant is `1.380xx10^(-23)JK^(-1)`, then the number of significant digits in the calculated value of the universal gas constant is

Answer

4

Explanation

Universal gas constant, `R = kN_(A)` , Where, k= Boltzmann constant and `N_(A)=` Avogadro's number
`:. R = 1.380 xx 10^(-23) xx 6.023 xx 10^(23) J//k mol = 8.312 ~= 8.312 J k^(-1) mol^(-1)`
Since, k and `N_(A)` both have four significant figures, so the value of R is also rounded off upto 4 significant figures.
[When number is rounded off, the number of significant figure is reduced, the last digit is increased by 1 if following digits `ge 5` and is left as such that if following digits is `le 4`] . Hence, correct integer is (4).